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https://issues.apache.org/jira/browse/YARN-8729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16601938#comment-16601938
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Tao Yang commented on YARN-8729:
--------------------------------
Thanks [~ebadger], [~cheersyang] for your reply.
{quote}
Setting isStopped to false before the whole NM startup has finished would
introduce a race condition where the NM says it's running, but it isn't fully
up yet.
{quote}
I think isStopped here is used as a switch which can control async updater
thread to run or stop, not a state, so that it's reasonable to set isStopped to
be false before starting the async updater thread, just as setting isStopped
to be true to stop the updater thread in current codes.
{quote}
I'm not sure if there is a functional reason, since the statusUpdater thread
loops on isStopped until it's false.
{quote}
The updater thread will exit if isStopped is true instead of waiting.
Related codes in StatusUpdaterRunnable:
{noformat}
public void run() {
int lastHeartbeatID = 0;
while (!isStopped) {
...
}
}
{noformat}
{quote}
could you please upload another patch to trigger jenkins?
{quote}
Done.
> Node status updater thread could be lost after it restarted
> -----------------------------------------------------------
>
> Key: YARN-8729
> URL: https://issues.apache.org/jira/browse/YARN-8729
> Project: Hadoop YARN
> Issue Type: Bug
> Components: nodemanager
> Affects Versions: 3.2.0
> Reporter: Tao Yang
> Assignee: Tao Yang
> Priority: Critical
> Attachments: YARN-8729.001.patch, YARN-8729.001.patch
>
>
> Today I found a lost NM whose node status updater thread was not exist after
> this thread restarted. In
> {{NodeStatusUpdaterImpl#rebootNodeStatusUpdaterAndRegisterWithRM}}, isStopped
> flag is not updated to be false before executing {{statusUpdater.start()}},
> so that if the thread is immediately started and found isStopped==true, it
> will exit without any log.
> Key codes in
> {{NodeStatusUpdaterImpl#rebootNodeStatusUpdaterAndRegisterWithRM}}:
> {code:java}
> statusUpdater.join();
> registerWithRM();
> statusUpdater = new Thread(statusUpdaterRunnable, "Node Status Updater");
> statusUpdater.start();
> this.isStopped = false; //this line should be moved before
> statusUpdater.start();
> LOG.info("NodeStatusUpdater thread is reRegistered and restarted");
> {code}
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