Hi Jeremy, that is unusual, is it reproduceable? Do you have details
on the stack for threads other than this thread doing the close?
It would be best if you could create a JIRA for this, the more detail
you could provide the better (full stacks and any log files)
https://issues.apache.org/jira/browse/ZOOKEEPER
Patrick
On Mon, Jan 31, 2011 at 10:26 AM, Jeremy Stribling <strib@nicira.com> wrote:
> I responded to someone off-list about this, but I just wanted to clarify to
> everyone that the part of the backtrace that isn't shown is entirely within
> my application, and zookeeper_close isn't being called from any Zookeeper
> completion thread.
>
> On 01/29/2011 11:23 AM, Jeremy Stribling wrote:
>>
>> Hi everyone,
>>
>> I use the multithreaded ZK C client library (3.3.2), and I'm seeing my
>> application hang, and the only thread in it that's doing anything
>> interesting is this one:
>>
>> Thread 8 (Thread 5644):
>> #0 0x00007f5d7bb5bbe4 in __lll_lock_wait () from /lib/libpthread.so.0
>> #1 0x00007f5d7bb59ad0 in pthread_cond_broadcast@@GLIBC_2.3.2 () from
>> /lib/libpthread.so.0
>> #2 0x00007f5d793628f6 in unlock_completion_list (l=0x32b4d68) at
>> .../zookeeper/src/c/src/mt_adaptor.c:66
>> #3 0x00007f5d79354d4b in free_completions (zh=0x32b4c80,
>> callCompletion=1, reason=-116) at .../zookeeper/src/c/src/zookeeper.c:1069
>> #4 0x00007f5d79355008 in cleanup_bufs (zh=0x32b4c80, callCompletion=1,
>> rc=-116) at .../thirdparty/zookeeper/src/c/src/zookeeper.c:1125
>> #5 0x00007f5d79353200 in destroy (zh=0x32b4c80) at
>> .../thirdparty/zookeeper/src/c/src/zookeeper.c:366
>> #6 0x00007f5d79358e0e in zookeeper_close (zh=0x32b4c80) at
>> .../zookeeper/src/c/src/zookeeper.c:2326
>> #7 0x00007f5d79356d18 in api_epilog (zh=0x32b4c80, rc=0) at
>> .../zookeeper/src/c/src/zookeeper.c:1661
>> #8 0x00007f5d79362f2f in adaptor_finish (zh=0x32b4c80) at
>> .../zookeeper/src/c/src/mt_adaptor.c:205
>> #9 0x00007f5d79358c8c in zookeeper_close (zh=0x32b4c80) at
>> .../zookeeper/src/c/src/zookeeper.c:2297
>> ....
>>
>> I've seen some threads online about how there's a race condition
>> associated with zookeeper_close, where if you app is making a synchronous
>> call at the same time using the closed zk_handle, there could be a hang.
>> However, my app makes no synchronous calls, and I'm 99% sure that no other
>> thread in my app is making any concurrent call into the library ('thread
>> apply all bt' in gdb doesn't show any other usage of the library, anyway).
>>
>> Has anyone seen this before? Any leads? Thanks,
>>
>> Jeremy
>
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