[Mono-dev] WebRequest timeouts after ThreadPool exhaustion

Fri Feb 12 14:13:10 UTC 2016

Happens on mono-4.3.2-branch/9f44a62 as well...

Alan: the PR you linked doesn't seem to be related, did you have another PR
in mind?

- Alex

2016-02-12 15:07 GMT+01:00 Alexander Köplinger <
alexander.koeplinger at xamarin.com>:

> I tried the testcase on master and couldn't reproduce there. I could,
> however, reproduce it on the 4.3.2 build I had installed
> (mono-4.3.2-branch/0df254d). I'm downloading a later 4.3.2 build right now
> to see if it still happens there, if it does then we need to backport
> something from master.
>
> - Alex
>
> 2016-02-12 15:04 GMT+01:00 Seif Attar <iam at seifattar.net>:
>
>> 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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>>
>>
>
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