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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-13826) S3A Deadlock in multipart copy due to thread pool limits.
Date Tue, 13 Dec 2016 10:13:58 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-13826?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15744762#comment-15744762

Steve Loughran commented on HADOOP-13826:

Ok, I've sat down for a review. Like I said before, the test needs some work. BTW, {{S3AFastOutputStream}}
is gone. Are you referring to {{S3ABlockOutputStream}}?
h2. {[S3AFileSystem]} 

Aren't there limits on the size of the AWS httpclient pool, or is there something I'm missing?

h2. {[ITestConcurrentOps]} 

This must be a subclass of {{AbstractS3ATestBase}}, so only run when {{-Dscale}} is set. This
will automatically give it extended test timeout, and allow that timeout to be overridden
in the config or on the maven command line.
* Must use {{path(subpath)}} to get a unique path which works in parallel execution, rather
than {{new Path("/ITestS3AManyFiles");}}
* {[getRestrictedFileSystem]} can just go "5M" and "10M" when setting sizes
* {{teardown()}} must check auxFS for being null, just in case something went wrong in setup.
* Note you can use {{ContractTestUtils.dataset()}} to create a 1MB file; it writes in a range
of values so it's easier to detect problems on reads. Not really needed here, but you should
get into the habit of using those methods where possible.
* {{testParallelRename}} must give the threads useful names. 
* {{testParallelRename}} should use Callables, so any exceptions raised in threads can be
raised by test runner. We don't want tests to go wrong and us not to notice.
* If {{testParallelRename}} logs exceptions, it must use {{LOG.error()}}
* {{testParallelRename}} must check that the dest files exist, and that the source ones don't.
Otherwise, it's not actually verifying that the rename worked,
only that a parallel series of operations completed.

> S3A Deadlock in multipart copy due to thread pool limits.
> ---------------------------------------------------------
>                 Key: HADOOP-13826
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13826
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: fs/s3
>    Affects Versions: 2.7.3
>            Reporter: Sean Mackrory
>            Assignee: Sean Mackrory
>            Priority: Critical
>         Attachments: HADOOP-13826.001.patch, HADOOP-13826.002.patch, HADOOP-13826.003.patch
> In testing HIVE-15093 we have encountered deadlocks in the s3a connector. The TransferManager
javadocs (http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/s3/transfer/TransferManager.html)
explain how this is possible:
> {quote}It is not recommended to use a single threaded executor or a thread pool with
a bounded work queue as control tasks may submit subtasks that can't complete until all sub
tasks complete. Using an incorrectly configured thread pool may cause a deadlock (I.E. the
work queue is filled with control tasks that can't finish until subtasks complete but subtasks
can't execute because the queue is filled).{quote}

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