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https://issues.apache.org/jira/browse/HDFS-17067?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17741785#comment-17741785
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ASF GitHub Bot commented on HDFS-17067:
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mccormickt12 commented on code in PR #5803:
URL: https://github.com/apache/hadoop/pull/5803#discussion_r1258991487
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hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/ObserverReadProxyProvider.java:
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@@ -648,6 +645,7 @@ public synchronized void close() throws IOException {
}
}
failoverProxy.close();
+ nnProbingThreadPool.shutdown();
Review Comment:
so whats the expected behavior? We finish, then it'll idle for how many
seconds (blocking)?
also its not obvious to me that the main thread timing out or the GC calling
close is the thing that we will be blocked on
> Use BlockingThreadPoolExecutorService for nnProbingThreadPool in
> ObserverReadProxy
> ----------------------------------------------------------------------------------
>
> Key: HDFS-17067
> URL: https://issues.apache.org/jira/browse/HDFS-17067
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Affects Versions: 3.4.0
> Reporter: Xing Lin
> Assignee: Xing Lin
> Priority: Major
> Labels: pull-request-available
>
> In HDFS-17030, we introduced an ExecutorService, to submit
> getHAServiceState() requests. We constructed the ExecutorService directly
> from a basic ThreadPoolExecutor, without setting _allowCoreThreadTimeOut_ to
> true. Then, the core thread will be kept up and running even when the main
> thread exits. To fix it, one could set _allowCoreThreadTimeOut_ to true.
> However, in this PR, we decide to directly use an existing executorService
> implementation (_BlockingThreadPoolExecutorService_) in hadoop instead. It
> takes care of setting _allowCoreThreadTimeOut_ and also allows setting the
> prefix for thread names.
> {code:java}
> private final ExecutorService nnProbingThreadPool =
> new ThreadPoolExecutor(1, 4, 1L, TimeUnit.MINUTES,
> new ArrayBlockingQueue<Runnable>(1024));
> {code}
> A second minor issue is we did not shutdown the executorService in close().
> It is a minor issue as close() will only be called when the garbage collector
> starts to reclaim an ObserverReadProxyProvider object, not when there is no
> reference to the ObserverReadProxyProvider object. The time between when an
> ObserverReadProxyProvider becomes dereferenced and when the garage collector
> actually starts to reclaim that object is out of control/under-defined
> (unless the program is shutdown with an explicit System.exit(1)).
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