[Mono-dev] WebRequest timeouts after ThreadPool exhaustion

Fri Feb 12 14:04:32 UTC 2016

Great, I'll try it out. Is the console app in that gist enough for a test
case?

@Mike @Jonathan we've faced bugs with previous versions of libc and
networking before, also some kernel issues. Update to latest if you can. I
can't reproduce with 3.12. I get timeouts but then it recovers when there
are available threads unlike with 4.x

On Fri, 12 Feb 2016 13:50 Alan <alan.mcgovern at gmail.com> wrote:

> It's also worth pointing out that the threadpool implementation has
> changed completely since mono 4.0. I believe the new threadpool
> implementation shipped as the default starting with mono 4.2 (or
> thereabouts). If you're on older Monos the odds are high whatever issue you
> have has been fixed already.
>
> Alan
>
> On 12 February 2016 at 13:48, Alan <alan.mcgovern at gmail.com> wrote:
>
>> Hey,
>>
>> We have just fixed some issues in that area. They are expected to ship as
>> part of a the next mono 4.3+ release. If you want to test them out in the
>> meantime you could try building mono with this PR [0] and see if it
>> resolves all your issues. If it doesn't then a testcase and bug report on
>> http://bugzilla.xamarin.com would be awesome!
>>
>> Thanks!
>>
>> [0] https://github.com/mono/mono/pull/2576
>>
>> On 12 February 2016 at 12:33, Mike Horsley <mhorsley at vqcomms.com> wrote:
>>
>>> we’ve also seen instances of webrequest timeouts that don’t recover (but
>>> curl worked) as well but haven’t got to the bottom of it yet.
>>>
>>>
>>>
>>> we ran your test app and see the same issue with mono 3.12 on OpenSUSE
>>> 13.2 (kernel 3.16.7, libc 2.19).
>>>
>>>
>>>
>>> we’ll add the diagnostics from your test app into ours and this will
>>> tell us whether we are seeing the same issue with the threadpool.
>>>
>>>
>>>
>>> regards
>>>
>>> Mike
>>>
>>>
>>>
>>> *From:* mono-devel-list-bounces at lists.ximian.com [mailto:
>>> mono-devel-list-bounces at lists.ximian.com] *On Behalf Of *Seif Attar
>>> *Sent:* Friday, February 12, 2016 10:43 AM
>>> *To:* mono-devel-list at lists.ximian.com
>>> *Subject:* [Mono-dev] WebRequest timeouts after ThreadPool exhaustion
>>>
>>>
>>>
>>> Hi,
>>>
>>> We are running mono 4.2.2 in prod and the VM that the process was
>>> running on had SAN failure and after storage recovered, all outgoing
>>> requests were timing out, even though doing a curl was working fine.
>>>
>>> Theory was that thread pool starved and somehow things didn't recover
>>> properly.
>>>
>>> Managed to reproduce with:
>>>
>>>
>>> https://gist.githubusercontent.com/seif/ae2defbfa5afa26fa8f6/raw/bef351eded56c882658a4bad60fa4818ad32d629/timeout.cs
>>>
>>> Even after ThreadPool finishes the tasks and has available threads, it
>>> never recovers and subsequent webrequests all timeout.
>>>
>>> Running on mono 4.2.2, linux kernel 4.2.0-27 and libc 2.21.
>>>
>>> Output from gdb is:
>>>
>>> (gdb) info threads
>>>   Id   Target Id         Frame
>>>   13   Thread 0x7fca903ff700 (LWP 27944) "cli" pthread_cond_wait@@GLIBC_2.3.2
>>> () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
>>>   12   Thread 0x7fca90b34700 (LWP 27945) "Finalizer" 0x00007fca911d70c9
>>> in futex_abstimed_wait (cancel=true, private=<optimised out>, abstime=0x0,
>>> expected=0, futex=0x948ae0) at sem_waitcommon.c:42
>>>   11   Thread 0x7fca8dfff700 (LWP 27946) "Timer-Scheduler"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   10   Thread 0x7fca91ba1700 (LWP 27947) "cli" __clock_nanosleep
>>> (clock_id=1, flags=1, req=0x7fca91ba0dc0, rem=0x7fca90f134aa
>>> <__clock_nanosleep+138>) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:48
>>>   9    Thread 0x7fca8ddfe700 (LWP 27948) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   8    Thread 0x7fca8dbfd700 (LWP 27949) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   7    Thread 0x7fca8d7fb700 (LWP 27951) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   6    Thread 0x7fca8d3f9700 (LWP 27953) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   5    Thread 0x7fca8d1f8700 (LWP 27954) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   4    Thread 0x7fca8cff7700 (LWP 27955) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   3    Thread 0x7fca8cdf6700 (LWP 27956) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>>   2    Thread 0x7fca8cbf5700 (LWP 27957) "Threadpool work"
>>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>>> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
>>> * 1    Thread 0x7fca91cf0780 (LWP 27942) "cli" 0x00007fca911d7e0d in
>>> read () at ../sysdeps/unix/syscall-template.S:81
>>>
>>> Could not reproduce on mono 3.12, but it happens on 4.0.3 and 4.2.2
>>>
>>> Is this a known issue? any workarounds? Tried setting MONO_DNS=1 to use
>>> the clr dns, but that didn't help.
>>>
>>> Let me know if there is any more info I need to provide.
>>>
>>> Thanks,
>>>
>>> Seif
>>>
>>> _______________________________________________
>>> Mono-devel-list mailing list
>>> Mono-devel-list at lists.ximian.com
>>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>>
>>>
>>
>
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