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https://issues.apache.org/jira/browse/HADOOP-14519?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16047047#comment-16047047
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Chen Liang edited comment on HADOOP-14519 at 6/12/17 9:10 PM:
--------------------------------------------------------------
Thanks [~jzhuge] for the catch! The patch LGTM. One minor thing though, I think
the patch slightly changed the syntax of this function. (Please correct me if
I'm wrong though).
Let's denote condition {{calls.isEmpty() && !shouldCloseConnection.get() &&
running.get()}} as condition A. The original logic works that, it only checks A
before calling wait, meaning when it gets notified, it returns from wait and
just proceed, potentially possible that A is still true at this point. While
the patch changes it that, even when it gets notified, as long as A is true, it
will keep looping. Could you please verify that this change to the syntax is
correct? Namely, {{calls.isEmpty() && !shouldCloseConnection.get() &&
running.get()}} is indeed expected to be false always after the object gets
notified. I'm inclined to believe it is all good based the fact of no test
failures.
was (Author: vagarychen):
Thanks [~jzhuge] for the catch! The patch LGTM. One minor thing though, I think
the patch slightly changed the syntax of this function. (Please correct me if
I'm wrong though).
Let's denote condition {{calls.isEmpty() && !shouldCloseConnection.get() &&
running.get()}} as condition A. The original logic works that, it only checks A
before calling wait, meaning when it gets notified, it returns from wait and
just proceed, potentially possible that A is still true at this point. While
the patch changes it that, even when it gets notified, as long as A is true, it
will keep looping. Could you please verify that this change to the syntax is
correct? I'm inclined to believe it is all good based the fact of no test
failures.
> Client$Connection#waitForWork may suffer spurious wakeup
> --------------------------------------------------------
>
> Key: HADOOP-14519
> URL: https://issues.apache.org/jira/browse/HADOOP-14519
> Project: Hadoop Common
> Issue Type: Bug
> Components: ipc
> Affects Versions: 2.8.0
> Reporter: John Zhuge
> Assignee: John Zhuge
> Priority: Critical
> Attachments: HADOOP-14519.001.patch
>
>
> {{Client$Connection#waitForWork}} may suffer spurious wakeup because the
> {{wait}} is not surrounded by a loop. See
> [https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#wait()].
> {code:title=Client$Connection#waitForWork}
> if (calls.isEmpty() && !shouldCloseConnection.get() && running.get()) {
> long timeout = maxIdleTime-
> (Time.now()-lastActivity.get());
> if (timeout>0) {
> try {
> wait(timeout); <<<<<<==== spurious wakeup
> } catch (InterruptedException e) {}
> }
> }
> {code}
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