##### General

- Overview
- Single Node Setup
- Cluster Setup
- Commands Reference
- FileSystem Shell
- Compatibility Specification
- Downstream Developer's Guide
- Admin Compatibility Guide
- Interface Classification
- FileSystem Specification

##### Common

- CLI Mini Cluster
- Native Libraries
- Proxy User
- Rack Awareness
- Secure Mode
- Service Level Authorization
- HTTP Authentication
- Credential Provider API
- Hadoop KMS
- Tracing
- Unix Shell Guide

##### HDFS

- Architecture
- User Guide
- Commands Reference
- NameNode HA With QJM
- NameNode HA With NFS
- Observer NameNode
- Federation
- ViewFs
- ViewFsOverloadScheme
- Snapshots
- Edits Viewer
- Image Viewer
- Permissions and HDFS
- Quotas and HDFS
- libhdfs (C API)
- WebHDFS (REST API)
- HttpFS
- Short Circuit Local Reads
- Centralized Cache Management
- NFS Gateway
- Rolling Upgrade
- Extended Attributes
- Transparent Encryption
- Multihoming
- Storage Policies
- Memory Storage Support
- Synthetic Load Generator
- Erasure Coding
- Disk Balancer
- Upgrade Domain
- DataNode Admin
- Router Federation
- Provided Storage

##### MapReduce

- Tutorial
- Commands Reference
- Compatibility with 1.x
- Encrypted Shuffle
- Pluggable Shuffle/Sort
- Distributed Cache Deploy
- Support for YARN Shared Cache

##### MapReduce REST APIs

- MR Application Master
- MR History Server

##### YARN

- Architecture
- Commands Reference
- Capacity Scheduler
- Fair Scheduler
- ResourceManager Restart
- ResourceManager HA
- Resource Model
- Node Labels
- Node Attributes
- Web Application Proxy
- Timeline Server
- Timeline Service V.2
- Writing YARN Applications
- YARN Application Security
- NodeManager
- Running Applications in Docker Containers
- Using CGroups
- Secure Containers
- Registry
- Reservation System
- Graceful Decommission
- Opportunistic Containers
- YARN Federation
- Shared Cache
- Using GPU
- Using FPGA
- Placement Constraints
- YARN UI2

##### YARN REST APIs

- Introduction
- Resource Manager
- Node Manager
- Timeline Server
- Timeline Service V.2

##### YARN Service

- Overview
- QuickStart
- Concepts
- Yarn Service API
- Service Discovery
- System Services

##### Submarine

- Index
- QuickStart
- Examples

##### Hadoop Compatible File Systems

- Aliyun OSS
- Amazon S3
- Azure Blob Storage
- Azure Data Lake Storage
- OpenStack Swift

##### Auth

- Overview
- Examples
- Configuration
- Building

##### Tools

- Hadoop Streaming
- Hadoop Archives
- Hadoop Archive Logs
- DistCp
- GridMix
- Rumen
- Resource Estimator Service
- Scheduler Load Simulator
- Hadoop Benchmarking

##### Reference

- Changelog and Release Notes
- Java API docs
- Unix Shell API
- Metrics

##### Configuration

- core-default.xml
- hdfs-default.xml
- hdfs-rbf-default.xml
- mapred-default.xml
- yarn-default.xml
- kms-default.xml
- httpfs-default.xml
- Deprecated Properties

# Troubleshooting

- Introduction
- Classpath Setup
  - ClassNotFoundException: org.apache.hadoop.fs.s3a.S3AFileSystem
  - ClassNotFoundException: com.amazonaws.services.s3.AmazonS3Client
  - java.lang.NoSuchMethodError referencing a com.amazonaws class
  - java.lang.NoSuchMethodError referencing an org.apache.hadoop class
- Authentication Failure
  - Authentication failure “The Filesystem URI contains login details.”
  - Authentication failure due to clock skew
  - “Bad Request” exception when working with AWS S3 Frankfurt, Seoul, or other “V4” endpoint
- AccessDeniedException “Access Denied”
  - AccessDeniedException “The AWS Access Key Id you provided does not exist in our records.”
  - AccessDeniedException All access to this object has been disabled
  - AccessDeniedException “Access denied” when trying to manipulate data
  - AccessDeniedException when using SSE-KMS
- Connectivity Problems
  - Error message “The bucket you are attempting to access must be addressed using the specified endpoint”
  - “Timeout waiting for connection from pool” when writing data
  - “Timeout waiting for connection from pool” when reading data
  - NoHttpResponseException
  - Out of heap memory when writing with via Fast Upload
  - MultiObjectDeleteException during delete or rename of files
  - “Failed to Sanitize XML document”
  - JSON Parse Error from AWS SDK
- Other Errors
  - SdkClientException Unable to verify integrity of data upload
  - AWSS3IOException The Content-MD5 you specified did not match what we received
  - When writing data: “java.io.FileNotFoundException: Completing multi-part upload”
  - Application hangs after reading a number of files
  - Issue: when writing data, HTTP Exceptions logged at info from AmazonHttpClient
  - AWSBadRequestException IllegalLocationConstraintException/The unspecified location constraint is incompatible
- File System Semantics
  - Visible S3 Inconsistency
  - FileNotFoundException even though the file was just written.
  - File not found in a directory listing, even though getFileStatus() finds it
  - File not visible/saved
  - File flush(), hsync and hflush() calls do not save data to S3
  - RemoteFileChangedException and read-during-overwrite
- S3 Server Side Encryption
  - AWSS3IOException KMS.NotFoundException “Invalid arn” when using SSE-KMS
  - Using SSE-C “Bad Request”
- Message appears in logs “Not all bytes were read from the S3ObjectInputStream”
  - FileNotFoundException Bucket does not exist.
- Other Issues
  - Enabling low-level logging
- Reducing failures by configuring retry policy

## Introduction

Common problems working with S3 are

1. Classpath setup
2. Authentication
3. S3 Inconsistency side-effects

Troubleshooting IAM Assumed Roles is covered in its specific documentation.

## Classpath Setup

Classpath is usually the first problem. For the S3A filesystem client, you need the Hadoop-specific filesystem clients, the very same AWS SDK library which Hadoop was built against, and any dependent libraries compatible with Hadoop and the specific JVM.

The classpath must be set up for the process talking to S3: if this is code running in the Hadoop cluster, the JARs must be on that classpath. That includes `distcp` and the `hadoop fs` command.

Critical: Do not attempt to “drop in” a newer version of the AWS SDK than that which the Hadoop version was built with Whatever problem you have, changing the AWS SDK version will not fix things, only change the stack traces you see.

Similarly, don’t try and mix a `hadoop-aws` JAR from one Hadoop release with that of any other. The JAR must be in sync with `hadoop-common` and some other Hadoop JARs.

Randomly changing hadoop- and aws- JARs in the hope of making a problem “go away” or to gain access to a feature you want, will not lead to the outcome you desire.

Tip: you can use mvnrepository to determine the dependency version requirements of a specific `hadoop-aws` JAR published by the ASF.

### `ClassNotFoundException: org.apache.hadoop.fs.s3a.S3AFileSystem`

These are Hadoop filesystem client classes, found in the `hadoop-aws` JAR. An exception reporting this class as missing means that this JAR is not on the classpath.

### `ClassNotFoundException: com.amazonaws.services.s3.AmazonS3Client`

(or other `com.amazonaws` class.)

This means that the `aws-java-sdk-bundle.jar` JAR is not on the classpath: add it.

### `java.lang.NoSuchMethodError` referencing a `com.amazonaws` class

This can be triggered by incompatibilities between the AWS SDK on the classpath and the version which Hadoop was compiled with.

The AWS SDK JARs change their signature enough between releases that the only way to safely update the AWS SDK version is to recompile Hadoop against the later version.

The sole fix is to use the same version of the AWS SDK with which Hadoop was built.

This can also be caused by having more than one version of an AWS SDK JAR on the classpath. If the full `aws-java-sdk-bundle<` JAR is on the classpath, do not add any of the `aws-sdk-` JARs.

### `java.lang.NoSuchMethodError` referencing an `org.apache.hadoop` class

This happens if the `hadoop-aws` and `hadoop-common` JARs are out of sync. You can’t mix them around: they have to have exactly matching version numbers.

## Authentication Failure

If Hadoop cannot authenticate with the S3 service endpoint, the client retries a number of times before eventually failing. When it finally gives up, it will report a message about signature mismatch:

    com.amazonaws.services.s3.model.AmazonS3Exception:
     The request signature we calculated does not match the signature you provided.
     Check your key and signing method.
      (Service: Amazon S3; Status Code: 403; Error Code: SignatureDoesNotMatch,

The likely cause is that you either have the wrong credentials or somehow the credentials were not readable on the host attempting to read or write the S3 Bucket.

Enabling debug logging for the package `org.apache.hadoop.fs.s3a` can help provide more information.

The most common cause is that you have the wrong credentials for any of the current authentication mechanism(s) —or somehow the credentials were not readable on the host attempting to read or write the S3 Bucket. However, there are a couple of system configuration problems (JVM version, system clock) which also need to be checked.

Most common: there’s an error in the configuration properties.

1. Make sure that the name of the bucket is the correct one. That is: check the URL.

2. If using a private S3 server, make sure endpoint in `fs.s3a.endpoint` has been set to this server -and that the client is not accidentally trying to authenticate with the public Amazon S3 service.

3. Make sure the property names are correct. For S3A, they are `fs.s3a.access.key` and `fs.s3a.secret.key` —you cannot just copy the S3N properties and replace `s3n` with `s3a`.

4. Make sure the properties are visible to the process attempting to talk to the object store. Placing them in `core-site.xml` is the standard mechanism.

5. If using session authentication, the session may have expired. Generate a new session token and secret.

6. If using environment variable-based authentication, make sure that the relevant variables are set in the environment in which the process is running.

The standard first step is: try to use the AWS command line tools with the same credentials, through a command such as:

    hadoop fs -ls s3a://my-bucket/

Note the trailing “/” here; without that the shell thinks you are trying to list your home directory under the bucket, which will only exist if explicitly created.

Finally, if you set the environment variables, you can take advantage of S3A’s support of environment-variable authentication by attempting the same ls operation. That is: unset the `fs.s3a` secrets and rely on the environment variables.

### Authentication failure “The Filesystem URI contains login details.”

    The Filesystem URI contains login details. This authentication mechanism is no longer supported.

The S3A connector no longer supports the dangerously insecure mechanism of passing login details within the S3A URLs.

Fix: use a more secure mechanism to pass down the secrets.

### Authentication failure due to clock skew

The timestamp is used in signing to S3, so as to defend against replay attacks. If the system clock is too far behind or ahead of Amazon’s, requests will be rejected.

This can surface as the situation where read requests are allowed, but operations which write to the bucket are denied.

Check the system clock.

### “Bad Request” exception when working with AWS S3 Frankfurt, Seoul, or other “V4” endpoint

S3 Frankfurt and Seoul only support the V4 authentication API.

Requests using the V2 API will be rejected with 400 `Bad Request`

    $ bin/hadoop fs -ls s3a://frankfurt/
    WARN s3a.S3AFileSystem: Client: Amazon S3 error 400: 400 Bad Request; Bad Request (retryable)

    com.amazonaws.services.s3.model.AmazonS3Exception: Bad Request (Service: Amazon S3;
     Status Code: 400; Error Code: 400 Bad Request; Request ID: 923C5D9E75E44C06),
      S3 Extended Request ID: HDwje6k+ANEeDsM6aJ8+D5gUmNAMguOk2BvZ8PH3g9z0gpH+IuwT7N19oQOnIr5CIx7Vqb/uThE=
        at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:1182)
        at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:770)
        at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:489)
        at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:310)
        at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3785)
        at com.amazonaws.services.s3.AmazonS3Client.headBucket(AmazonS3Client.java:1107)
        at com.amazonaws.services.s3.AmazonS3Client.doesBucketExist(AmazonS3Client.java:1070)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.verifyBucketExists(S3AFileSystem.java:307)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.initialize(S3AFileSystem.java:284)
        at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2793)
        at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:101)
        at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2830)
        at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2812)
        at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:389)
        at org.apache.hadoop.fs.Path.getFileSystem(Path.java:356)
        at org.apache.hadoop.fs.shell.PathData.expandAsGlob(PathData.java:325)
        at org.apache.hadoop.fs.shell.Command.expandArgument(Command.java:235)
        at org.apache.hadoop.fs.shell.Command.expandArguments(Command.java:218)
        at org.apache.hadoop.fs.shell.FsCommand.processRawArguments(FsCommand.java:103)
        at org.apache.hadoop.fs.shell.Command.run(Command.java:165)
        at org.apache.hadoop.fs.FsShell.run(FsShell.java:315)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:90)
        at org.apache.hadoop.fs.FsShell.main(FsShell.java:373)
    ls: doesBucketExist on frankfurt-new: com.amazonaws.services.s3.model.AmazonS3Exception:
      Bad Request (Service: Amazon S3; Status Code: 400; Error Code: 400 Bad Request;

This happens when trying to work with any S3 service which only supports the “V4” signing API —but the client is configured to use the default S3 service endpoint.

The S3A client needs to be given the endpoint to use via the `fs.s3a.endpoint` property.

As an example, the endpoint for S3 Frankfurt is `s3.eu-central-1.amazonaws.com`:

    <property>
      <name>fs.s3a.endpoint</name>
      <value>s3.eu-central-1.amazonaws.com</value>
    </property>

## `AccessDeniedException` “Access Denied”

### AccessDeniedException “The AWS Access Key Id you provided does not exist in our records.”

The value of `fs.s3a.access.key` does not match a known access key ID. It may be mistyped, or the access key may have been deleted by one of the account managers.

    java.nio.file.AccessDeniedException: bucket: doesBucketExist on bucket:
        com.amazonaws.services.s3.model.AmazonS3Exception:
        The AWS Access Key Id you provided does not exist in our records.
         (Service: Amazon S3; Status Code: 403; Error Code: InvalidAccessKeyId;
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:214)
      at org.apache.hadoop.fs.s3a.Invoker.once(Invoker.java:111)
      at org.apache.hadoop.fs.s3a.Invoker.lambda$retry$3(Invoker.java:260)
      at org.apache.hadoop.fs.s3a.Invoker.retryUntranslated(Invoker.java:314)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:256)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:231)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.verifyBucketExists(S3AFileSystem.java:366)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.initialize(S3AFileSystem.java:302)
      at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:3354)
      at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:124)
      at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:3403)
      at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:3371)
      at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:477)
      at org.apache.hadoop.fs.contract.AbstractBondedFSContract.init(AbstractBondedFSContract.java:72)
      at org.apache.hadoop.fs.contract.AbstractFSContractTestBase.setup(AbstractFSContractTestBase.java:177)
      at org.apache.hadoop.fs.s3a.commit.AbstractCommitITest.setup(AbstractCommitITest.java:163)
      at org.apache.hadoop.fs.s3a.commit.AbstractITCommitMRJob.setup(AbstractITCommitMRJob.java:129)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
      at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
      at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
      at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
      at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
      at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:48)
      at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
      at org.junit.internal.runners.statements.FailOnTimeout$StatementThread.run(FailOnTimeout.java:74)
    Caused by: com.amazonaws.services.s3.model.AmazonS3Exception:
                   The AWS Access Key Id you provided does not exist in our records.
                    (Service: Amazon S3; Status Code: 403; Error Code: InvalidAccessKeyId;
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1638)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1303)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1055)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:743)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:717)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:699)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:667)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:649)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:513)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4229)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4176)
      at com.amazonaws.services.s3.AmazonS3Client.getAcl(AmazonS3Client.java:3381)
      at com.amazonaws.services.s3.AmazonS3Client.getBucketAcl(AmazonS3Client.java:1160)
      at com.amazonaws.services.s3.AmazonS3Client.getBucketAcl(AmazonS3Client.java:1150)
      at com.amazonaws.services.s3.AmazonS3Client.doesBucketExist(AmazonS3Client.java:1266)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.lambda$verifyBucketExists$1(S3AFileSystem.java:367)
      at org.apache.hadoop.fs.s3a.Invoker.once(Invoker.java:109)
      ... 27 more

### `AccessDeniedException` All access to this object has been disabled

Caller has no permission to access the bucket at all.

    doesBucketExist on fdsd: java.nio.file.AccessDeniedException: fdsd: doesBucketExist on fdsd:
     com.amazonaws.services.s3.model.AmazonS3Exception: All access to this object has been disabled
     (Service: Amazon S3; Status Code: 403; Error Code: AllAccessDisabled; Request ID: E6229D7F8134E64F;
      S3 Extended Request ID: 6SzVz2t4qa8J2Wxo/oc8yBuB13Mgrn9uMKnxVY0hsBd2kU/YdHzW1IaujpJdDXRDCQRX3f1RYn0=),
      S3 Extended Request ID: 6SzVz2t4qa8J2Wxo/oc8yBuB13Mgrn9uMKnxVY0hsBd2kU/YdHzW1IaujpJdDXRDCQRX3f1RYn0=:AllAccessDisabled
     All access to this object has been disabled (Service: Amazon S3; Status Code: 403;
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:205)
      at org.apache.hadoop.fs.s3a.S3ALambda.once(S3ALambda.java:122)
      at org.apache.hadoop.fs.s3a.S3ALambda.lambda$retry$2(S3ALambda.java:233)
      at org.apache.hadoop.fs.s3a.S3ALambda.retryUntranslated(S3ALambda.java:288)
      at org.apache.hadoop.fs.s3a.S3ALambda.retry(S3ALambda.java:228)
      at org.apache.hadoop.fs.s3a.S3ALambda.retry(S3ALambda.java:203)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.verifyBucketExists(S3AFileSystem.java:357)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.initialize(S3AFileSystem.java:293)
      at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:3288)
      at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:123)
      at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:3337)
      at org.apache.hadoop.fs.FileSystem$Cache.getUnique(FileSystem.java:3311)
      at org.apache.hadoop.fs.FileSystem.newInstance(FileSystem.java:529)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool$BucketInfo.run(S3GuardTool.java:997)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool.run(S3GuardTool.java:309)
      at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool.run(S3GuardTool.java:1218)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool.main(S3GuardTool.java:1227)
    Caused by: com.amazonaws.services.s3.model.AmazonS3Exception: All access to this object has been disabled
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1638)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1303)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1055)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:743)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:717)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:699)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:667)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:649)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:513)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4229)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4176)
      at com.amazonaws.services.s3.AmazonS3Client.getAcl(AmazonS3Client.java:3381)
      at com.amazonaws.services.s3.AmazonS3Client.getBucketAcl(AmazonS3Client.java:1160)
      at com.amazonaws.services.s3.AmazonS3Client.getBucketAcl(AmazonS3Client.java:1150)
      at com.amazonaws.services.s3.AmazonS3Client.doesBucketExist(AmazonS3Client.java:1266)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.lambda$verifyBucketExists$1(S3AFileSystem.java:360)
      at org.apache.hadoop.fs.s3a.S3ALambda.once(S3ALambda.java:120)

Check the name of the bucket is correct, and validate permissions for the active user/role.

### `AccessDeniedException` “Access denied” when trying to manipulate data

Data can be read, but attempts to write data or manipulate the store fail with 403/Access denied.

The bucket may have an access policy which the request does not comply with. or the caller does not have the right to access the data.

    java.nio.file.AccessDeniedException: test/: PUT 0-byte object  on test/:
     com.amazonaws.services.s3.model.AmazonS3Exception: Access Denied (Service: Amazon S3; Status Code: 403;
     Error Code: AccessDenied; Request ID: EDC662AD2EEEA33C;
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:210)
      at org.apache.hadoop.fs.s3a.Invoker.once(Invoker.java:110)
      at org.apache.hadoop.fs.s3a.Invoker.lambda$retry$3(Invoker.java:259)
      at org.apache.hadoop.fs.s3a.Invoker.retryUntranslated(Invoker.java:313)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:255)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:230)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.createEmptyObject(S3AFileSystem.java:2691)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.createFakeDirectory(S3AFileSystem.java:2666)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.innerMkdirs(S3AFileSystem.java:2030)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.mkdirs(S3AFileSystem.java:1965)
      at org.apache.hadoop.fs.FileSystem.mkdirs(FileSystem.java:2305)

In the AWS S3 management console, select the “permissions” tab for the bucket, then “bucket policy”.

If there is a bucket access policy, e.g. required encryption headers, then the settings of the s3a client must guarantee the relevant headers are set (e.g. the encryption options match). Note: S3 Default Encryption options are not considered here: if the bucket policy requires AES256 as the encryption policy on PUT requests, then the encryption option must be set in the hadoop client so that the header is set.

Otherwise, the problem will likely be that the user does not have full access to the operation. Check what they were trying to (read vs write) and then look at the permissions of the user/role.

If the client using assumed roles, and a policy is set in `fs.s3a.assumed.role.policy`, then that policy declares all the rights which the caller has.

### `AccessDeniedException` when using SSE-KMS

When trying to write or read SEE-KMS-encrypted data, the client gets a `java.nio.AccessDeniedException` with the error 403/Forbidden.

The caller does not have the permissions to access the key with which the data was encrypted.

## Connectivity Problems

### Error message “The bucket you are attempting to access must be addressed using the specified endpoint”

This surfaces when `fs.s3a.endpoint` is configured to use an S3 service endpoint which is neither the original AWS one, `s3.amazonaws.com` , nor the one where the bucket is hosted. The error message contains the redirect target returned by S3, which can be used to determine the correct value for `fs.s3a.endpoint`.

    org.apache.hadoop.fs.s3a.AWSS3IOException: Received permanent redirect response
      to bucket.s3-us-west-2.amazonaws.com.  This likely indicates that the S3
      endpoint configured in fs.s3a.endpoint does not match the AWS region
      containing the bucket.: The bucket you are attempting to access must be
      addressed using the specified endpoint. Please send all future requests to
      this endpoint. (Service: Amazon S3; Status Code: 301;
      Error Code: PermanentRedirect; Request ID: 7D39EC1021C61B11)
          at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:132)
          at org.apache.hadoop.fs.s3a.S3AFileSystem.initMultipartUploads(S3AFileSystem.java:287)
          at org.apache.hadoop.fs.s3a.S3AFileSystem.initialize(S3AFileSystem.java:203)
          at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2895)
          at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:102)
          at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2932)
          at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2914)
          at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:390)

1. Use the Specific endpoint of the bucket’s S3 service
2. If not using “V4” authentication (see above), the original S3 endpoint can be used:

    <property>
      <name>fs.s3a.endpoint</name>
      <value>s3.amazonaws.com</value>
    </property>

Using the explicit endpoint for the region is recommended for speed and to use the V4 signing API.

### “Timeout waiting for connection from pool” when writing data

This happens when using the output stream thread pool runs out of capacity.

    [s3a-transfer-shared-pool1-t20] INFO  http.AmazonHttpClient (AmazonHttpClient.java:executeHelper(496))
     - Unable to execute HTTP request:
      Timeout waiting for connection from poolorg.apache.http.conn.ConnectionPoolTimeoutException:
       Timeout waiting for connection from pool
      at org.apache.http.impl.conn.PoolingClientConnectionManager.leaseConnection(PoolingClientConnectionManager.java:230)
      at org.apache.http.impl.conn.PoolingClientConnectionManager$1.getConnection(PoolingClientConnectionManager.java:199)
      at sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at com.amazonaws.http.conn.ClientConnectionRequestFactory$Handler.invoke(ClientConnectionRequestFactory.java:70)
      at com.amazonaws.http.conn.$Proxy10.getConnection(Unknown Source)
      at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:424)
      at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:884)
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:55)
      at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:728)
      at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:489)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:310)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3785)
      at com.amazonaws.services.s3.AmazonS3Client.doUploadPart(AmazonS3Client.java:2921)
      at com.amazonaws.services.s3.AmazonS3Client.uploadPart(AmazonS3Client.java:2906)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.uploadPart(S3AFileSystem.java:1025)
      at org.apache.hadoop.fs.s3a.S3ABlockOutputStream$MultiPartUpload$1.call(S3ABlockOutputStream.java:360)
      at org.apache.hadoop.fs.s3a.S3ABlockOutputStream$MultiPartUpload$1.call(S3ABlockOutputStream.java:355)
      at org.apache.hadoop.fs.s3a.BlockingThreadPoolExecutorService$CallableWithPermitRelease.call(BlockingThreadPoolExecutorService.java:239)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)

Make sure that `fs.s3a.connection.maximum` is at least larger than `fs.s3a.threads.max`.

    <property>
      <name>fs.s3a.threads.max</name>
      <value>20</value>
    </property>

    <property>
      <name>fs.s3a.connection.maximum</name>
      <value>30</value>
    </property>

### “Timeout waiting for connection from pool” when reading data

This happens when more threads are trying to read from an S3A system than the maximum number of allocated HTTP connections.

Set `fs.s3a.connection.maximum` to a larger value (and at least as large as `fs.s3a.threads.max`)

### `NoHttpResponseException`

The HTTP Server did not respond.

    2017-02-07 10:01:07,950 INFO [s3a-transfer-shared-pool1-t7] com.amazonaws.http.AmazonHttpClient:
      Unable to execute HTTP request: bucket.s3.amazonaws.com:443 failed to respond
    org.apache.http.NoHttpResponseException: bucket.s3.amazonaws.com:443 failed to respond
      at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:143)
      at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:57)
      at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:261)
      at org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:283)
      at org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:259)
      at org.apache.http.impl.conn.ManagedClientConnectionImpl.receiveResponseHeader(ManagedClientConnectionImpl.java:209)
      at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:272)
      at com.amazonaws.http.protocol.SdkHttpRequestExecutor.doReceiveResponse(SdkHttpRequestExecutor.java:66)
      at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:124)
      at org.apache.http.impl.client.DefaultRequestDirector.tryExecute(DefaultRequestDirector.java:686)
      at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:488)
      at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:884)
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:55)
      at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:728)
      at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:489)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:310)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3785)
      at com.amazonaws.services.s3.AmazonS3Client.copyPart(AmazonS3Client.java:1731)
      at com.amazonaws.services.s3.transfer.internal.CopyPartCallable.call(CopyPartCallable.java:41)
      at com.amazonaws.services.s3.transfer.internal.CopyPartCallable.call(CopyPartCallable.java:28)
      at org.apache.hadoop.fs.s3a.SemaphoredDelegatingExecutor$CallableWithPermitRelease.call(SemaphoredDelegatingExecutor.java:222)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)

Probably network problems, unless it really is an outage of S3.

### Out of heap memory when writing with via Fast Upload

This can happen when using the upload buffering mechanism uses memory (either `fs.s3a.fast.upload.buffer=array` or `fs.s3a.fast.upload.buffer=bytebuffer`).

More data is being generated than in the JVM than it can upload to S3 —and so much data has been buffered that the JVM has run out of memory.

1. Consult S3A Fast Upload Thread Tuning for detail on this issue and options to address it.

2. Switch to buffering to disk, rather than memory.

This surfaces if, while a multipart upload was taking place, all outstanding multipart uploads were garbage collected. The upload operation cannot complete because the data uploaded has been deleted.

Consult Cleaning up After Incremental Upload Failures for details on how the multipart purge timeout can be set. If multipart uploads are failing with the message above, it may be a sign that this value is too low.

### `MultiObjectDeleteException` during delete or rename of files

    Exception in thread "main" com.amazonaws.services.s3.model.MultiObjectDeleteException:
        Status Code: 0, AWS Service: null, AWS Request ID: null, AWS Error Code: null,
        AWS Error Message: One or more objects could not be deleted, S3 Extended Request ID: null
      at com.amazonaws.services.s3.AmazonS3Client.deleteObjects(AmazonS3Client.java:1745)

This happens when trying to delete multiple objects, and one of the objects could not be deleted. It should not occur just because the object is missing. More specifically: at the time this document was written, we could not create such a failure.

It will occur if the caller lacks the permission to delete any of the objects.

Consult the log to see the specifics of which objects could not be deleted. Do you have permission to do so?

If this operation is failing for reasons other than the caller lacking permissions:

1. Try setting `fs.s3a.multiobjectdelete.enable` to `false`.
2. Consult HADOOP-11572 for up to date advice.

### “Failed to Sanitize XML document”

    org.apache.hadoop.fs.s3a.AWSClientIOException: getFileStatus on test/testname/streaming/:
      com.amazonaws.AmazonClientException: Failed to sanitize XML document
      destined for handler class com.amazonaws.services.s3.model.transform.XmlResponsesSaxParser$ListBucketHandler:
      Failed to sanitize XML document destined for handler class
       com.amazonaws.services.s3.model.transform.XmlResponsesSaxParser$ListBucketHandler
        at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:105)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.getFileStatus(S3AFileSystem.java:1462)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.innerListStatus(S3AFileSystem.java:1227)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.listStatus(S3AFileSystem.java:1203)
        at org.apache.hadoop.fs.s3a.S3AGlobber.listStatus(S3AGlobber.java:69)
        at org.apache.hadoop.fs.s3a.S3AGlobber.doGlob(S3AGlobber.java:210)
        at org.apache.hadoop.fs.s3a.S3AGlobber.glob(S3AGlobber.java:125)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.globStatus(S3AFileSystem.java:1853)
        at org.apache.hadoop.fs.s3a.S3AFileSystem.globStatus(S3AFileSystem.java:1841)

We believe this is caused by the connection to S3 being broken. See HADOOP-13811.

It may go away if the operation is retried.

### JSON Parse Error from AWS SDK

Sometimes a JSON Parse error is reported with the stack trace in the `com.amazonaws`,

Again, we believe this is caused by the connection to S3 being broken.

It may go away if the operation is retried.

## Other Errors

### `SdkClientException` Unable to verify integrity of data upload

Something has happened to the data as it was uploaded.

    Caused by: org.apache.hadoop.fs.s3a.AWSClientIOException: saving output on dest/_task_tmp.-ext-10000/_tmp.000000_0:
        com.amazonaws.AmazonClientException: Unable to verify integrity of data upload.
        Client calculated content hash (contentMD5: L75PalQk0CIhTp04MStVOA== in base 64)
        didn't match hash (etag: 37ace01f2c383d6b9b3490933c83bb0f in hex) calculated by Amazon S3.
        You may need to delete the data stored in Amazon S3.
        (metadata.contentMD5: L75PalQk0CIhTp04MStVOA==, md5DigestStream: null,
        bucketName: ext2, key: dest/_task_tmp.-ext-10000/_tmp.000000_0):
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:144)
      at org.apache.hadoop.fs.s3a.S3AOutputStream.close(S3AOutputStream.java:121)
      at org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:72)
      at org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:106)
      at org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat$1.close(HiveIgnoreKeyTextOutputFormat.java:99)
      at org.apache.hadoop.hive.ql.exec.FileSinkOperator$FSPaths.closeWriters(FileSinkOperator.java:190)
      ... 22 more
    Caused by: com.amazonaws.AmazonClientException: Unable to verify integrity of data upload.
      Client calculated content hash (contentMD5: L75PalQk0CIhTp04MStVOA== in base 64)
      didn't match hash (etag: 37ace01f2c383d6b9b3490933c83bb0f in hex) calculated by Amazon S3.
      You may need to delete the data stored in Amazon S3.
      (metadata.contentMD5: L75PalQk0CIhTp04MStVOA==, md5DigestStream: null,
      bucketName: ext2, key: dest/_task_tmp.-ext-10000/_tmp.000000_0)
      at com.amazonaws.services.s3.AmazonS3Client.putObject(AmazonS3Client.java:1492)
      at com.amazonaws.services.s3.transfer.internal.UploadCallable.uploadInOneChunk(UploadCallable.java:131)
      at com.amazonaws.services.s3.transfer.internal.UploadCallable.call(UploadCallable.java:123)
      at com.amazonaws.services.s3.transfer.internal.UploadMonitor.call(UploadMonitor.java:139)
      at com.amazonaws.services.s3.transfer.internal.UploadMonitor.call(UploadMonitor.java:47)
      ... 4 more

As it uploads data to S3, the AWS SDK builds up an MD5 checksum of what was PUT/POSTed. When S3 returns the checksum of the uploaded data, that is compared with the local checksum. If there is a mismatch, this error is reported.

The uploaded data is already on S3 and will stay there, though if this happens during a multipart upload, it may not be visible (but still billed: clean up your multipart uploads via the `hadoop s3guard uploads` command).

Possible causes for this

1. A (possibly transient) network problem, including hardware faults.
2. A proxy server is doing bad things to the data.
3. Some signing problem, especially with third-party S3-compatible object stores.

This is a very, very rare occurrence.

If the problem is a signing one, try changing the signature algorithm.

    <property>
      <name>fs.s3a.signing-algorithm</name>
      <value>S3SignerType</value>
    </property>

We cannot make any promises that it will work, only that it has been known to make the problem go away “once”

### `AWSS3IOException` The Content-MD5 you specified did not match what we received

Reads work, but writes, even `mkdir`, fail:

    org.apache.hadoop.fs.s3a.AWSS3IOException: copyFromLocalFile(file:/tmp/hello.txt, s3a://bucket/hello.txt)
        on file:/tmp/hello.txt:
        The Content-MD5 you specified did not match what we received.
        (Service: Amazon S3; Status Code: 400; Error Code: BadDigest; Request ID: 4018131225),
        S3 Extended Request ID: null
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:127)
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:69)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.copyFromLocalFile(S3AFileSystem.java:1494)
      at org.apache.hadoop.tools.cloudup.Cloudup.uploadOneFile(Cloudup.java:466)
      at org.apache.hadoop.tools.cloudup.Cloudup.access$000(Cloudup.java:63)
      at org.apache.hadoop.tools.cloudup.Cloudup$1.call(Cloudup.java:353)
      at org.apache.hadoop.tools.cloudup.Cloudup$1.call(Cloudup.java:350)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:748)
    Caused by: com.amazonaws.services.s3.model.AmazonS3Exception:
        The Content-MD5 you specified did not match what we received.
        (Service: Amazon S3; Status Code: 400; Error Code: BadDigest; Request ID: 4018131225),
        S3 Extended Request ID: null
      at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:1307)
      at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:894)
      at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:597)
      at com.amazonaws.http.AmazonHttpClient.doExecute(AmazonHttpClient.java:363)
      at com.amazonaws.http.AmazonHttpClient.executeWithTimer(AmazonHttpClient.java:329)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:308)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3659)
      at com.amazonaws.services.s3.AmazonS3Client.putObject(AmazonS3Client.java:1422)
      at com.amazonaws.services.s3.transfer.internal.UploadCallable.uploadInOneChunk(UploadCallable.java:131)
      at com.amazonaws.services.s3.transfer.internal.UploadCallable.call(UploadCallable.java:123)
      at com.amazonaws.services.s3.transfer.internal.UploadMonitor.call(UploadMonitor.java:139)
      at com.amazonaws.services.s3.transfer.internal.UploadMonitor.call(UploadMonitor.java:47)
      at org.apache.hadoop.fs.s3a.BlockingThreadPoolExecutorService$CallableWithPermitRelease.call(BlockingThreadPoolExecutorService.java:239)
      ... 4 more

This stack trace was seen when interacting with a third-party S3 store whose expectations of headers related to the AWS V4 signing mechanism was not compatible with that of the specific AWS SDK Hadoop was using.

Workaround: revert to V2 signing.

    <property>
      <name>fs.s3a.signing-algorithm</name>
      <value>S3SignerType</value>
    </property>

### When writing data: “java.io.FileNotFoundException: Completing multi-part upload”

A multipart upload was trying to complete, but failed as there was no upload with that ID.

    java.io.FileNotFoundException: Completing multi-part upload on fork-5/test/multipart/1c397ca6-9dfb-4ac1-9cf7-db666673246b:
     com.amazonaws.services.s3.model.AmazonS3Exception: The specified upload does not exist.
      The upload ID may be invalid, or the upload may have been aborted or completed.
       (Service: Amazon S3; Status Code: 404; Error Code: NoSuchUpload;
      at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:1182)
      at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:770)
      at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:489)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:310)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3785)
      at com.amazonaws.services.s3.AmazonS3Client.completeMultipartUpload(AmazonS3Client.java:2705)
      at org.apache.hadoop.fs.s3a.S3ABlockOutputStream$MultiPartUpload.complete(S3ABlockOutputStream.java:473)
      at org.apache.hadoop.fs.s3a.S3ABlockOutputStream$MultiPartUpload.access$200(S3ABlockOutputStream.java:382)
      at org.apache.hadoop.fs.s3a.S3ABlockOutputStream.close(S3ABlockOutputStream.java:272)
      at org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:72)
      at org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:106)

This can happen when all outstanding uploads have been aborted, including the active ones.

If the bucket has a lifecycle policy of deleting multipart uploads, make sure that the expiry time of the deletion is greater than that required for all open writes to complete the write, and for all jobs using the S3A committers to commit their work.

### Application hangs after reading a number of files

The pool of https client connections and/or IO threads have been used up, and none are being freed.

1. The pools aren’t big enough. See “Timeout waiting for connection from pool”
2. Likely root cause: whatever code is reading files isn’t calling `close()` on the input streams. Make sure your code does this! And if it’s someone else’s: make sure you have a recent version; search their issue trackers to see if its a known/fixed problem. If not, it’s time to work with the developers, or come up with a workaround (i.e closing the input stream yourself).

### Issue: when writing data, HTTP Exceptions logged at info from `AmazonHttpClient`

    [s3a-transfer-shared-pool4-t6] INFO  http.AmazonHttpClient (AmazonHttpClient.java:executeHelper(496))
     - Unable to execute HTTP request: hwdev-steve-ireland-new.s3.amazonaws.com:443 failed to respond
    org.apache.http.NoHttpResponseException: bucket.s3.amazonaws.com:443 failed to respond
      at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:143)
      at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:57)
      at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:261)
      at org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:283)
      at org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:259)
      at org.apache.http.impl.conn.ManagedClientConnectionImpl.receiveResponseHeader(ManagedClientConnectionImpl.java:209)
      at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:272)
      at com.amazonaws.http.protocol.SdkHttpRequestExecutor.doReceiveResponse(SdkHttpRequestExecutor.java:66)
      at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:124)
      at org.apache.http.impl.client.DefaultRequestDirector.tryExecute(DefaultRequestDirector.java:686)
      at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:488)
      at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:884)
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
      at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:55)
      at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:728)
      at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:489)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:310)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3785)
      at com.amazonaws.services.s3.AmazonS3Client.copyPart(AmazonS3Client.java:1731)
      at com.amazonaws.services.s3.transfer.internal.CopyPartCallable.call(CopyPartCallable.java:41)
      at com.amazonaws.services.s3.transfer.internal.CopyPartCallable.call(CopyPartCallable.java:28)
      at org.apache.hadoop.fs.s3a.BlockingThreadPoolExecutorService$CallableWithPermitRelease.call(BlockingThreadPoolExecutorService.java:239)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)

These are HTTP I/O exceptions caught and logged inside the AWS SDK. The client will attempt to retry the operation; it may just be a transient event. If there are many such exceptions in logs, it may be a symptom of connectivity or network problems.

### `AWSBadRequestException` IllegalLocationConstraintException/The unspecified location constraint is incompatible

     Cause: org.apache.hadoop.fs.s3a.AWSBadRequestException: put on :
      com.amazonaws.services.s3.model.AmazonS3Exception:
       The unspecified location constraint is incompatible for the region specific
        endpoint this request was sent to.
        (Service: Amazon S3; Status Code: 400; Error Code: IllegalLocationConstraintException;

      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:178)
      at org.apache.hadoop.fs.s3a.S3ALambda.execute(S3ALambda.java:64)
      at org.apache.hadoop.fs.s3a.WriteOperationHelper.uploadObject(WriteOperationHelper.java:451)
      at org.apache.hadoop.fs.s3a.commit.magic.MagicCommitTracker.aboutToComplete(MagicCommitTracker.java:128)
      at org.apache.hadoop.fs.s3a.S3ABlockOutputStream.close(S3ABlockOutputStream.java:373)
      at org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:72)
      at org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:101)
      at org.apache.hadoop.hive.ql.io.orc.WriterImpl.close(WriterImpl.java:2429)
      at org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat$OrcRecordWriter.close(OrcOutputFormat.java:106)
      at org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat$OrcRecordWriter.close(OrcOutputFormat.java:91)
      ...
      Cause: com.amazonaws.services.s3.model.AmazonS3Exception:
       The unspecified location constraint is incompatible for the region specific endpoint
       this request was sent to. (Service: Amazon S3; Status Code: 400; Error Code: IllegalLocationConstraintException;
       Request ID: EEBC5A08BCB3A645)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1588)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1258)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1030)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:742)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:716)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:699)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:667)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:649)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:513)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4221)
      ...

Something has been trying to write data to “/”.

## File System Semantics

These are the issues where S3 does not appear to behave the way a filesystem “should”.

### Visible S3 Inconsistency

Amazon S3 is an eventually consistent object store. That is: not a filesystem.

To reduce visible inconsistencies, use the S3Guard consistency cache.

By default, Amazon S3 offers read-after-create consistency: a newly created file is immediately visible. There is a small quirk: a negative GET may be cached, such that even if an object is immediately created, the fact that there “wasn’t” an object is still remembered.

That means the following sequence on its own will be consistent

    touch(path) -> getFileStatus(path)

But this sequence may be inconsistent.

    getFileStatus(path) -> touch(path) -> getFileStatus(path)

A common source of visible inconsistencies is that the S3 metadata database —the part of S3 which serves list requests— is updated asynchronously. Newly added or deleted files may not be visible in the index, even though direct operations on the object (`HEAD` and `GET`) succeed.

That means the `getFileStatus()` and `open()` operations are more likely to be consistent with the state of the object store, but without S3Guard enabled, directory list operations such as `listStatus()`, `listFiles()`, `listLocatedStatus()`, and `listStatusIterator()` may not see newly created files, and still list old files.

### `FileNotFoundException` even though the file was just written.

This can be a sign of consistency problems. It may also surface if there is some asynchronous file write operation still in progress in the client: the operation has returned, but the write has not yet completed. While the S3A client code does block during the `close()` operation, we suspect that asynchronous writes may be taking place somewhere in the stack —this could explain why parallel tests fail more often than serialized tests.

### File not found in a directory listing, even though `getFileStatus()` finds it

(Similarly: deleted file found in listing, though `getFileStatus()` reports that it is not there)

This is a visible sign of updates to the metadata server lagging behind the state of the underlying filesystem.

Fix: Use S3Guard.

### File not visible/saved

The files in an object store are not visible until the write has been completed. In-progress writes are simply saved to a local file/cached in RAM and only uploaded. at the end of a write operation. If a process terminated unexpectedly, or failed to call the `close()` method on an output stream, the pending data will have been lost.

### File `flush()`, `hsync` and `hflush()` calls do not save data to S3

Again, this is due to the fact that the data is cached locally until the `close()` operation. The S3A filesystem cannot be used as a store of data if it is required that the data is persisted durably after every `Syncable.hflush()` or `Syncable.hsync()` call. This includes resilient logging, HBase-style journaling and the like. The standard strategy here is to save to HDFS and then copy to S3.

### `RemoteFileChangedException` and read-during-overwrite

    org.apache.hadoop.fs.s3a.RemoteFileChangedException: re-open `s3a://my-bucket/test/file.txt':
      ETag change reported by S3 while reading at position 1949.
      Version f9c186d787d4de9657e99f280ba26555 was unavailable
      at org.apache.hadoop.fs.s3a.impl.ChangeTracker.processResponse(ChangeTracker.java:137)
      at org.apache.hadoop.fs.s3a.S3AInputStream.reopen(S3AInputStream.java:200)
      at org.apache.hadoop.fs.s3a.S3AInputStream.lambda$lazySeek$1(S3AInputStream.java:346)
      at org.apache.hadoop.fs.s3a.Invoker.lambda$retry$2(Invoker.java:195)
      at org.apache.hadoop.fs.s3a.Invoker.once(Invoker.java:109)
      at org.apache.hadoop.fs.s3a.Invoker.lambda$retry$3(Invoker.java:265)
      at org.apache.hadoop.fs.s3a.Invoker.retryUntranslated(Invoker.java:322)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:261)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:193)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:215)
      at org.apache.hadoop.fs.s3a.S3AInputStream.lazySeek(S3AInputStream.java:339)
      at org.apache.hadoop.fs.s3a.S3AInputStream.read(S3AInputStream.java:372)

If an S3 object is updated while an S3A filesystem reader has an open `InputStream` on it, the reader may encounter `RemoteFileChangedException`. This occurs if the S3A `InputStream` needs to re-open the object (e.g. during a seek()) and detects the change.

If the change detection mode is configured to ‘warn’, a warning like the following will be seen instead of `RemoteFileChangedException`:

    WARN  - ETag change detected on re-open s3a://my-bucket/test/readFileToChange.txt at 1949.
     Expected f9c186d787d4de9657e99f280ba26555 got 043abff21b7bd068d2d2f27ccca70309

Using a third-party S3 implementation that doesn’t support eTags might result in the following error.

    org.apache.hadoop.fs.s3a.NoVersionAttributeException: `s3a://my-bucket/test/file.txt':
     Change detection policy requires ETag
      at org.apache.hadoop.fs.s3a.impl.ChangeTracker.processResponse(ChangeTracker.java:153)
      at org.apache.hadoop.fs.s3a.S3AInputStream.reopen(S3AInputStream.java:200)
      at org.apache.hadoop.fs.s3a.S3AInputStream.lambda$lazySeek$1(S3AInputStream.java:346)
      at org.apache.hadoop.fs.s3a.Invoker.lambda$retry$2(Invoker.java:195)
      at org.apache.hadoop.fs.s3a.Invoker.once(Invoker.java:109)
      at org.apache.hadoop.fs.s3a.Invoker.lambda$retry$3(Invoker.java:265)
      at org.apache.hadoop.fs.s3a.Invoker.retryUntranslated(Invoker.java:322)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:261)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:193)
      at org.apache.hadoop.fs.s3a.Invoker.retry(Invoker.java:215)
      at org.apache.hadoop.fs.s3a.S3AInputStream.lazySeek(S3AInputStream.java:339)
      at org.apache.hadoop.fs.s3a.S3AInputStream.read(S3AInputStream.java:372)

If the change policy is `versionid` there are a number of possible causes

- The bucket does not have object versioning enabled.
- The bucket does have versioning enabled, but the object being read was created before versioning was enabled.
- The bucket is on a third-party store which does not support object versioning.

See Handling Read-During-Overwrite for more information.

## S3 Server Side Encryption

### `AWSS3IOException` `KMS.NotFoundException` “Invalid arn” when using SSE-KMS

When performing file operations, the user may run into an issue where the KMS key arn is invalid.

    org.apache.hadoop.fs.s3a.AWSS3IOException: innerMkdirs on /test:
     com.amazonaws.services.s3.model.AmazonS3Exception:
      Invalid arn (Service: Amazon S3; Status Code: 400; Error Code: KMS.NotFoundException;
       Request ID: CA89F276B3394565),
       S3 Extended Request ID: ncz0LWn8zor1cUO2fQ7gc5eyqOk3YfyQLDn2OQNoe5Zj/GqDLggUYz9QY7JhdZHdBaDTh+TL5ZQ=:
       Invalid arn (Service: Amazon S3; Status Code: 400; Error Code: KMS.NotFoundException; Request ID: CA89F276B3394565)
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:194)
      at org.apache.hadoop.fs.s3a.S3AUtils.translateException(S3AUtils.java:117)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.mkdirs(S3AFileSystem.java:1541)
      at org.apache.hadoop.fs.FileSystem.mkdirs(FileSystem.java:2230)
      at org.apache.hadoop.fs.contract.AbstractFSContractTestBase.mkdirs(AbstractFSContractTestBase.java:338)
      at org.apache.hadoop.fs.contract.AbstractFSContractTestBase.setup(AbstractFSContractTestBase.java:193)
      at org.apache.hadoop.fs.s3a.scale.S3AScaleTestBase.setup(S3AScaleTestBase.java:90)
      at org.apache.hadoop.fs.s3a.scale.AbstractSTestS3AHugeFiles.setup(AbstractSTestS3AHugeFiles.java:77)
      at sun.reflect.GeneratedMethodAccessor12.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
      at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
      at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
      at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
      at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
      at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
      at org.junit.internal.runners.statements.FailOnTimeout$StatementThread.run(FailOnTimeout.java:74)
    Caused by: com.amazonaws.services.s3.model.AmazonS3Exception:
     Invalid arn (Service: Amazon S3; Status Code: 400; Error Code: KMS.NotFoundException; Request ID: CA89F276B3394565)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1588)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1258)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1030)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:742)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:716)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:699)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:667)
      at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:649)
      at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:513)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4221)
      at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:4168)
      at com.amazonaws.services.s3.AmazonS3Client.putObject(AmazonS3Client.java:1718)
      at com.amazonaws.services.s3.transfer.internal.UploadCallable.uploadInOneChunk(UploadCallable.java:133)
      at com.amazonaws.services.s3.transfer.internal.UploadCallable.call(UploadCallable.java:125)
      at com.amazonaws.services.s3.transfer.internal.UploadMonitor.call(UploadMonitor.java:143)
      at com.amazonaws.services.s3.transfer.internal.UploadMonitor.call(UploadMonitor.java:48)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)

Possible causes:

- the KMS key ARN is entered incorrectly, or
- the KMS key referenced by the ARN is in a different region than the S3 bucket being used.

### Using SSE-C “Bad Request”

When performing file operations the user may run into an unexpected 400/403 error such as

    org.apache.hadoop.fs.s3a.AWSS3IOException: getFileStatus on fork-4/:
     com.amazonaws.services.s3.model.AmazonS3Exception:
    Bad Request (Service: Amazon S3; Status Code: 400;
    Error Code: 400 Bad Request; Request ID: 42F9A1987CB49A99),
    S3 Extended Request ID: jU2kcwaXnWj5APB14Cgb1IKkc449gu2+dhIsW/+7x9J4D+VUkKvu78mBo03oh9jnOT2eoTLdECU=:
    Bad Request (Service: Amazon S3; Status Code: 400; Error Code: 400 Bad Request; Request ID: 42F9A1987CB49A99)

This can happen in the cases of not specifying the correct SSE-C encryption key. Such cases can be as follows: 1. An object is encrypted using SSE-C on S3 and either the wrong encryption type is used, no encryption is specified, or the SSE-C specified is incorrect. 2. A directory is encrypted with a SSE-C keyA and the user is trying to move a file using configured SSE-C keyB into that structure.

## Message appears in logs “Not all bytes were read from the S3ObjectInputStream”

This is a message which can be generated by the Amazon SDK when the client application calls `abort()` on the HTTP input stream, rather than reading to the end of the file/stream and causing `close()`. The S3A client does call `abort()` when seeking round large files, so leading to the message.

No ASF Hadoop releases have shipped with an SDK which prints this message when used by the S3A client. However third party and private builds of Hadoop may cause the message to be logged.

Ignore it. The S3A client does call `abort()`, but that’s because our benchmarking shows that it is generally more efficient to abort the TCP connection and initiate a new one than read to the end of a large file.

Note: the threshold when data is read rather than the stream aborted can be tuned by `fs.s3a.readahead.range`; seek policy in `fs.s3a.experimental.fadvise`.

### `FileNotFoundException` Bucket does not exist.

The bucket does not exist.

    java.io.FileNotFoundException: Bucket stevel45r56666 does not exist
      at org.apache.hadoop.fs.s3a.S3AFileSystem.verifyBucketExists(S3AFileSystem.java:361)
      at org.apache.hadoop.fs.s3a.S3AFileSystem.initialize(S3AFileSystem.java:293)
      at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:3288)
      at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:123)
      at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:3337)
      at org.apache.hadoop.fs.FileSystem$Cache.getUnique(FileSystem.java:3311)
      at org.apache.hadoop.fs.FileSystem.newInstance(FileSystem.java:529)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool$BucketInfo.run(S3GuardTool.java:997)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool.run(S3GuardTool.java:309)
      at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool.run(S3GuardTool.java:1218)
      at org.apache.hadoop.fs.s3a.s3guard.S3GuardTool.main(S3GuardTool.java:1227)

Check the URI. If using a third-party store, verify that you’ve configured the client to talk to the specific server in `fs.s3a.endpoint`.

## Other Issues

### Enabling low-level logging

The AWS SDK and the Apache S3 components can be configured to log at more detail, as can S3A itself.

    log4j.logger.org.apache.hadoop.fs.s3a=DEBUG
    log4j.logger.com.amazonaws.request=DEBUG
    log4j.logger.com.amazonaws.thirdparty.apache.http=DEBUG

If using the “unshaded” JAR, then the Apache HttpClient can be directly configured:

    log4j.logger.org.apache.http=DEBUG

This produces a log such as this, which is for a V4-authenticated PUT of a 0-byte file used as an empty directory marker

    execchain.MainClientExec (MainClientExec.java:execute(255)) - Executing request PUT /test/ HTTP/1.1
    execchain.MainClientExec (MainClientExec.java:execute(266)) - Proxy auth state: UNCHALLENGED
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(135)) - http-outgoing-0 >> PUT /test/ HTTP/1.1
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> Host: ireland-new.s3-eu-west-1.amazonaws.com
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> x-amz-content-sha256: UNSIGNED-PAYLOAD
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> Authorization: AWS4-HMAC-SHA256 Credential=AKIAIYZ5JEEEER/20170904/eu-west-1/s3/aws4_request,  ...
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> X-Amz-Date: 20170904T172929Z
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> User-Agent: Hadoop 3.0.0-beta-1, aws-sdk-java/1.11.134 ...
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> amz-sdk-invocation-id: 75b530f8-ad31-1ad3-13db-9bd53666b30d
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> amz-sdk-retry: 0/0/500
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> Content-Type: application/octet-stream
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> Content-Length: 0
    http.headers (LoggingManagedHttpClientConnection.java:onRequestSubmitted(138)) - http-outgoing-0 >> Connection: Keep-Alive
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "PUT /test/ HTTP/1.1[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "Host: ireland-new.s3-eu-west-1.amazonaws.com[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "x-amz-content-sha256: UNSIGNED-PAYLOAD[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "Authorization: AWS4-HMAC-SHA256 Credential=AKIAIYZ5JEEEER/20170904/eu-west-1/s3/aws4_request, ,,,
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "X-Amz-Date: 20170904T172929Z[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "User-Agent: 3.0.0-beta-1, aws-sdk-java/1.11.134  ...
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "amz-sdk-invocation-id: 75b530f8-ad31-1ad3-13db-9bd53666b30d[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "amz-sdk-retry: 0/0/500[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "Content-Type: application/octet-stream[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "Content-Length: 0[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "Connection: Keep-Alive[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 >> "[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "HTTP/1.1 200 OK[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "x-amz-id-2: mad9GqKztzlL0cdnCKAj9GJOAs+DUjbSC5jRkO7W1E7Nk2BUmFvt81bhSNPGdZmyyKqQI9i/B/A=[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "x-amz-request-id: C953D2FE4ABF5C51[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "Date: Mon, 04 Sep 2017 17:29:30 GMT[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "ETag: "d41d8cd98f00b204e9800998ecf8427e"[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "Content-Length: 0[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "Server: AmazonS3[\r][\n]"
    http.wire (Wire.java:wire(72)) - http-outgoing-0 << "[\r][\n]"
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(124)) - http-outgoing-0 << HTTP/1.1 200 OK
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(127)) - http-outgoing-0 << x-amz-id-2: mad9GqKztzlL0cdnCKAj9GJOAs+DUjbSC5jRkO7W1E7Nk2BUmFvt81bhSNPGdZmyyKqQI9i/B/A=
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(127)) - http-outgoing-0 << x-amz-request-id: C953D2FE4ABF5C51
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(127)) - http-outgoing-0 << Date: Mon, 04 Sep 2017 17:29:30 GMT
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(127)) - http-outgoing-0 << ETag: "d41d8cd98f00b204e9800998ecf8427e"
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(127)) - http-outgoing-0 << Content-Length: 0
    http.headers (LoggingManagedHttpClientConnection.java:onResponseReceived(127)) - http-outgoing-0 << Server: AmazonS3
    execchain.MainClientExec (MainClientExec.java:execute(284)) - Connection can be kept alive for 60000 MILLISECONDS

## Reducing failures by configuring retry policy

The S3A client can ba configured to retry those operations which are considered retryable. That can be because they are idempotent, or because the failure happened before the request was processed by S3.

The number of retries and interval between each retry can be configured:

    <property>
      <name>fs.s3a.attempts.maximum</name>
      <value>20</value>
      <description>How many times we should retry commands on transient errors,
      excluding throttling errors.</description>
    </property>

    <property>
      <name>fs.s3a.retry.interval</name>
      <value>500ms</value>
      <description>
        Interval between retry attempts.
      </description>
    </property>

Not all failures are retried. Specifically excluded are those considered unrecoverable:

- Low-level networking: `UnknownHostException`, `NoRouteToHostException`.
- 302 redirects.
- Missing resources, 404/`FileNotFoundException`.
- HTTP 416 response/`EOFException`. This can surface if the length of a file changes while another client is reading it.
- Failures during execution or result processing of non-idempotent operations where it is considered likely that the operation has already taken place.

In future, others may be added to this list.

When one of these failures arises in the S3/S3A client, the retry mechanism is bypassed and the operation will fail.

Warning: the S3A client considers DELETE, PUT and COPY operations to be idempotent, and will retry them on failure. These are only really idempotent if no other client is attempting to manipulate the same objects, such as: renaming() the directory tree or uploading files to the same location. Please don’t do that. Given that the emulated directory rename and delete operations are not atomic, even without retries, multiple S3 clients working with the same paths can interfere with each other