[concurrency-interest] LinkedBlockingDeque deadlock? (Test case)

David Holmes davidcholmes at aapt.net.au
Fri Jul 17 22:28:14 EDT 2009


Sorry Ryan, misread the stack trace. The main thread is interacting with the
executors LBQ not the application one.

I'll see if I can use this test to reproduce the issue on Monday.

David Holmes

> -----Original Message-----
> From: concurrency-interest-bounces at cs.oswego.edu
> [mailto:concurrency-interest-bounces at cs.oswego.edu]On Behalf Of David
> Holmes
> Sent: Saturday, 18 July 2009 12:15 PM
> To: Ryan Betts; concurrency-interest at cs.oswego.edu
> Cc: core-libs-dev
> Subject: Re: [concurrency-interest] LinkedBlockingDeque deadlock? (Test
> case)
>
>
>
>
> Ryan,
>
> Thanks very much for this.
>
> When this "deadlocks" does top show whether the java process is actually
> quiet or is it still consuming CPU? I notice that in the stack
> dump the main
> thread is in the process of unlocking the lock that the other threads are
> waiting upon and hence the system is not deadlocked - unless that main
> thread is actually "stuck" somewhere. Can you take a series of
> stackdumps to
> see if/how the main thread is executing?
>
> Feel free to just send them to me rather than the mailing lists.
>
> Thanks,
> David Holmes
>
> > -----Original Message-----
> > From: concurrency-interest-bounces at cs.oswego.edu
> > [mailto:concurrency-interest-bounces at cs.oswego.edu]On Behalf Of Ryan
> > Betts
> > Sent: Saturday, 18 July 2009 2:48 AM
> > To: concurrency-interest at cs.oswego.edu
> > Cc: core-libs-dev
> > Subject: Re: [concurrency-interest] LinkedBlockingDeque deadlock? (Test
> > case)
> >
> >
> > Hello all,
> >
> > I've been working with Ariel on the j.u.c.LinkedBlockingDeque deadlock
> > we observe. The attached test case reproduces the deadlock
> > intermittently, usually requiring several minutes. The test simply
> > prints periods until it deadlocks. Attempts to produce a simpler test
> > case using only ReentrantLock or without an ExecutorService were
> > unsuccessful.
> >
> > I've attached jstack reports showing the deadlocked case and the dmesg
> > output from one of the servers that reproduces the defect. To date,
> > this deadlock only occurs on our 2 socket i7s.
> >
> > We have not filed a defect with Sun for this issue. If that would be
> > helpful (or necessary), we would of course happily oblige.
> >
> > $ java -version
> > java version "1.6.0"
> > OpenJDK  Runtime Environment (build 1.6.0-b09)
> > OpenJDK 64-Bit Server VM (build 1.6.0-b09, mixed mode)
> >
> > $ uname -a
> > Linux host3e 2.6.18-128.1.16.el5 #1 SMP Tue Jun 30 06:07:26 EDT 2009
> > x86_64 x86_64 x86_64 GNU/Linux
> >
> > $ javac LBDLockPatternTest.java
> > $ java LBDLockPatternTest
> >
> >
> > Thank you,
> > *--Ryan.
> >
> >
> >
>
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