[erlang-bugs] VM locks up on write to socket (and now it seems to file too)

Patrik Nyblom <>
Thu Dec 6 13:01:38 CET 2012


Hi!

Good! The workaround isn't all that costly either, so I think we could 
put that in R16 as is. It would be good if the OS bug got fixed though, 
but I think that's also on it's way.

Cheers,
/Patrik

On 12/05/2012 02:20 PM, Peter Membrey wrote:
> Hi Patrik,
>
> Really sorry for the delay in getting back to you!
>
> I tried the same test on RHEL 6.3 using the patched version and
> everything seems fine. No stuck threads and the VM is still happy and
> responsive.
>
> I'm currently working on a load testing app to try and trigger the
> issue on demand in the application itself, but I suspect your patch
> has done the trick!
>
> Thanks for fixing this so fast and sorry again for the delay in
> getting back in touch!
>
> Cheers,
>
> Pete
>
>
>
> On 30 November 2012 02:46, Patrik Nyblom <> wrote:
>> Hi!
>>
>> On 11/29/2012 04:41 AM, Peter Membrey wrote:
>>> Hi Patrik,
>>>
>>> I can also confirm that this bug exists on Red Hat Enterprise Linux
>>> 6.3. I'll raise a support ticket with them as well.
>>>
>>> A workaround in the vm would be nice if you have time… :-)
>> Could you try the attached diff and see if it works for your environment? It
>> would seem nothing is written when 0 is returned, so it should be safe to
>> try again...
>>
>> Cheers,
>> /Patrik
>>
>>
>>> Cheers,
>>>
>>> Pete
>>>
>>>
>>> On 29 November 2012 01:23, Patrik Nyblom <> wrote:
>>>> Hi again!
>>>>
>>>> No problem reproducing when I've got CentOS 6.3... The following commands
>>>> in
>>>> the Erlang shell:
>>>> {ok,L} = gen_tcp:listen(4747,[{active,false}]).
>>>> {ok,S} = gen_tcp:connect("localhost",4747,[{active,false}]).
>>>> {ok,A} = gen_tcp:accept(L).
>>>> gen_tcp:send(A,binary:copy(<<$a:8>>,2158022464)).
>>>>
>>>> gives the following strace:
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [pid 15859] writev(10, [{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"...,
>>>> 2158022464}], 1) = 0
>>>> [.....]
>>>>
>>>> While on ubuntu for example it works like it should...Looks like a kernel
>>>> bug to me... I wonder if this should be worked around or just reported...
>>>> I
>>>> suppose both... Sigh...
>>>>
>>>> /Patrik
>>>>
>>>>
>>>> On 11/28/2012 05:23 PM, Peter Membrey wrote:
>>>>> Hi,
>>>>>
>>>>> No problem, I'll do what I can to help - thanks for looking into this
>>>>> so quickly!
>>>>>
>>>>> Any idea what might be causing it?
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Pete
>>>>>
>>>>> On 28 November 2012 23:54, Patrik Nyblom <> wrote:
>>>>>> Hi!
>>>>>>
>>>>>> I'll upgrade the CentOS VM I have to 6.3 (only had 6.1 :() and see if I
>>>>>> can
>>>>>> reproduce. If that fails, could you run a VM with a patch to try to
>>>>>> handle
>>>>>> the unexpected case and see if that fixes it?
>>>>>>
>>>>>> Cheers,
>>>>>> /Patrik
>>>>>>
>>>>>> On 11/24/2012 02:57 PM, Peter Membrey wrote:
>>>>>>> Hi guys,
>>>>>>>
>>>>>>> Thanks for getting back in touch so quickly!
>>>>>>>
>>>>>>> I did do an lsof on the process and I can confirm that it was
>>>>>>> definitely a socket. However by that time the application it had been
>>>>>>> trying to send to had been killed. When I checked the sockets were
>>>>>>> showing as waiting to close. Unfortunately I didn't think to do an
>>>>>>> lsof until after the apps had been shut down. I was hoping the VM
>>>>>>> would recover if I killed the app that had upset it. However even
>>>>>>> after all the apps connected had been shut down, the issue didn't
>>>>>>> resolve.
>>>>>>>
>>>>>>> The application receives requests from a client, which contains two
>>>>>>> data items. The stream ID and a timestamp. Both are encoded as big
>>>>>>> integer unsigned numbers. The server then looks through the file
>>>>>>> referenced by the stream ID and uses the timestamp as an index. The
>>>>>>> file format is currently really simple, in the form of:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> <Timestamp:64/native-integer,Length:32/native-integer,Data:Length/binary>>
>>>>>>>
>>>>>>> There is an index file that provides an offset into the file based on
>>>>>>> time stamp, but basically it opens the file, and reads sequentially
>>>>>>> through it until it finds the timestamps that it cares about. In this
>>>>>>> case it reads all data with a greater timestamp until the end of the
>>>>>>> file is reached. It's possible the client is sending an incorrect
>>>>>>> timestamp, and maybe too much data is being read. However the loop is
>>>>>>> very primitive - it reads all the data in one go before passing it
>>>>>>> back to the protocol handler to send down the socket; so by that time
>>>>>>> even though the response is technically incorrect and the app has
>>>>>>> failed, it should still not cause the VM any issues.
>>>>>>>
>>>>>>> The data is polled every 10 seconds by the client app so I would not
>>>>>>> expect there to be 2GB of new data to send. I'm afraid my C skills are
>>>>>>> somewhat limited, so I'm not sure how to put together a sample app to
>>>>>>> try out writev. The platform is 64bit CentOS 6.3 (equivalent to RHEL
>>>>>>> 6.3) so I'm not expecting any strange or weird behaviour from the OS
>>>>>>> level but of course I could be completely wrong there. The OS is
>>>>>>> running directly on hardware, so there's no VM layer to worry about.
>>>>>>>
>>>>>>> Hope this might offer some additional clues…
>>>>>>>
>>>>>>> Thanks again!
>>>>>>>
>>>>>>> Kind Regards,
>>>>>>>
>>>>>>> Peter Membrey
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 24 November 2012 00:13, Patrik Nyblom <> wrote:
>>>>>>>> Hi again!
>>>>>>>>
>>>>>>>> Could you go back to the version without the printouts and get back
>>>>>>>> to
>>>>>>>> the
>>>>>>>> situation where writev loops returning 0 (as in the strace)? If so,
>>>>>>>> it
>>>>>>>> would
>>>>>>>> be really interesting to see an 'lsof' of the beam process, to see if
>>>>>>>> this
>>>>>>>> file descriptor really is open and is a socket...
>>>>>>>>
>>>>>>>> The thing is that writev with a vector that is not empty, would never
>>>>>>>> return
>>>>>>>> 0 for a non blocking socket. Not on any modern (i.e. not ancient)
>>>>>>>> POSIX
>>>>>>>> compliant system anyway. Of course it is a *really* large item you
>>>>>>>> are
>>>>>>>> trying to write there, but it should be no problem for a 64bit linux.
>>>>>>>>
>>>>>>>> Also I think there is no use finding the Erlang code, I'll take that
>>>>>>>> back,
>>>>>>>> It would be more interesting to see what really happens at the OS/VM
>>>>>>>> level
>>>>>>>> in this case.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Patrik
>>>>>>>>
>>>>>>>>
>>>>>>>> On 11/23/2012 01:49 AM, Loïc Hoguin wrote:
>>>>>>>>> Sending this on behalf of someone who didn't manage to get the email
>>>>>>>>> sent
>>>>>>>>> to this list after 2 attempts. If someone can check if he's hold up
>>>>>>>>> or
>>>>>>>>> something that'd be great.
>>>>>>>>>
>>>>>>>>> Anyway he has a big issue so I hope I can relay the conversation
>>>>>>>>> reliably.
>>>>>>>>>
>>>>>>>>> Thanks!
>>>>>>>>>
>>>>>>>>> On 11/23/2012 01:45 AM, Peter Membrey wrote:
>>>>>>>>>> From: Peter Membrey <>
>>>>>>>>>> Date: 22 November 2012 19:02
>>>>>>>>>> Subject: VM locks up on write to socket (and now it seems to file
>>>>>>>>>> too)
>>>>>>>>>> To: 
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Hi guys,
>>>>>>>>>>
>>>>>>>>>> I wrote a simple database application called CakeDB
>>>>>>>>>> (https://github.com/pmembrey/cakedb) that basically spends its time
>>>>>>>>>> reading and writing files and sockets. There's very little in the
>>>>>>>>>> way
>>>>>>>>>> of complex logic. It is running on CentOS 6.3 with all the updates
>>>>>>>>>> applied. I hit this problem on R15B02 so I rolled back to R15B01
>>>>>>>>>> but
>>>>>>>>>> the issue remained. Erlang was built from source.
>>>>>>>>>>
>>>>>>>>>> The machine has two Intel X5690 CPUs giving 12 cores plus HT. I've
>>>>>>>>>> tried various arguments for the VM but so far nothing has prevented
>>>>>>>>>> the problem. At the moment I'm using:
>>>>>>>>>>
>>>>>>>>>> +K
>>>>>>>>>> +A 6
>>>>>>>>>> +sbt tnnps
>>>>>>>>>>
>>>>>>>>>> The issue I'm seeing is that one of the scheduler threads will hit
>>>>>>>>>> 100% cpu usage and the entire VM will become unresponsive. When
>>>>>>>>>> this
>>>>>>>>>> happens, I am not able to connect via the console with attach and
>>>>>>>>>> entop is also unable to connect. I can still establish TCP
>>>>>>>>>> connections
>>>>>>>>>> to the application, but I never receive a response. A standard kill
>>>>>>>>>> signal will cause the VM to shut down (it doesn't need -9).
>>>>>>>>>>
>>>>>>>>>> Due to the pedigree of the VM I am quite willing to accept that
>>>>>>>>>> I've
>>>>>>>>>> made a fundamental mistake in my code. I am pretty sure that the
>>>>>>>>>> way
>>>>>>>>>> I
>>>>>>>>>> am doing the file IO could result in some race conditions. However,
>>>>>>>>>> my
>>>>>>>>>> poor code aside, from what I understand, I still shouldn't be able
>>>>>>>>>> to
>>>>>>>>>> crash / deadlock the VM like this.
>>>>>>>>>>
>>>>>>>>>> The issue doesn't seem to be caused by load. The app can fail when
>>>>>>>>>> it's very busy, but also when it is practically idle. I haven't
>>>>>>>>>> been
>>>>>>>>>> able to find a trigger or any other explanation for the failure.
>>>>>>>>>>
>>>>>>>>>> The thread maxing out the CPU is attempting to write data to the
>>>>>>>>>> socket:
>>>>>>>>>>
>>>>>>>>>> (gdb) bt
>>>>>>>>>> #0  0x00007f9882ab6377 in writev () from /lib64/libc.so.6
>>>>>>>>>> #1  0x000000000058a81f in tcp_inet_output (data=0x2407570,
>>>>>>>>>> event=<value optimized out>) at drivers/common/inet_drv.c:9681
>>>>>>>>>> #2  tcp_inet_drv_output (data=0x2407570, event=<value optimized
>>>>>>>>>> out>)
>>>>>>>>>> at drivers/common/inet_drv.c:9601
>>>>>>>>>> #3  0x00000000004b773f in erts_port_task_execute
>>>>>>>>>> (runq=0x7f98826019c0,
>>>>>>>>>> curr_port_pp=0x7f9881639338)  at beam/erl_port_task.c:858
>>>>>>>>>> #4  0x00000000004afd83 in schedule (p=<value optimized out>,
>>>>>>>>>> calls=<value optimized out>) at beam/erl_process.c:6533
>>>>>>>>>> #5  0x0000000000539ca2 in process_main () at beam/beam_emu.c:1268
>>>>>>>>>> #6  0x00000000004b1279 in sched_thread_func (vesdp=0x7f9881639280)
>>>>>>>>>> at
>>>>>>>>>> beam/erl_process.c:4834
>>>>>>>>>> #7  0x00000000005ba726 in thr_wrapper (vtwd=0x7fff6cfe2300) at
>>>>>>>>>> pthread/ethread.c:106
>>>>>>>>>> #8  0x00007f9882f78851 in start_thread () from
>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>> #9  0x00007f9882abe11d in clone () from /lib64/libc.so.6
>>>>>>>>>> (gdb)
>>>>>>>>>>
>>>>>>>>>> I then tried running strace on that thread and got (indefinitely):
>>>>>>>>>>
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> writev(15, [{"", 2158022464}], 1)       = 0
>>>>>>>>>> ...
>>>>>>>>>>
>>>>>>>>>>      From what I can tell, it's trying to write data to a socket,
>>>>>>>>>> which
>>>>>>>>>> is
>>>>>>>>>> succeeding, but writing 0 bytes. From the earlier definitions in
>>>>>>>>>> the
>>>>>>>>>> source file, an error condition would be signified by a negative
>>>>>>>>>> number. Any other result is the number of bytes written, in this
>>>>>>>>>> case
>>>>>>>>>> 0. I'm not sure if this is desired behaviour or not. I've tried
>>>>>>>>>> killing the application on the other end of the socket, but it has
>>>>>>>>>> no
>>>>>>>>>> effect on the VM.
>>>>>>>>>>
>>>>>>>>>> I have enabled debugging for the inet code, so hopefully this will
>>>>>>>>>> give a little more insight. I am currently trying to reproduce the
>>>>>>>>>> condition, but as I really have no idea what causes it, it's pretty
>>>>>>>>>> much a case of wait and see.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> **** UPDATE ****
>>>>>>>>>>
>>>>>>>>>> I managed to lock up the VM again, but this time it was caused by
>>>>>>>>>> file
>>>>>>>>>> IO,
>>>>>>>>>> probably from the debugging statements. Although it worked fine for
>>>>>>>>>> some
>>>>>>>>>> time
>>>>>>>>>> the last entry in the file was cut off.
>>>>>>>>>>
>>>>>>>>>>      From GDB:
>>>>>>>>>>
>>>>>>>>>> (gdb) info threads
>>>>>>>>>>        53 Thread 0x7f83e988b700 (LWP 8621)  0x00007f83ea6da54d in
>>>>>>>>>> read
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libpthread.so.0
>>>>>>>>>>        52 Thread 0x7f83e8c8f700 (LWP 8622)  0x00007f83ea6d743c in
>>>>>>>>>> pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
>>>>>>>>>>        51 Thread 0x7f83e818d700 (LWP 8623)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        50 Thread 0x7f83e816b700 (LWP 8624)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        49 Thread 0x7f83e8149700 (LWP 8625)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        48 Thread 0x7f83e8127700 (LWP 8626)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        47 Thread 0x7f83e8105700 (LWP 8627)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        46 Thread 0x7f83e80e3700 (LWP 8628)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        45 Thread 0x7f83e80c1700 (LWP 8629)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        44 Thread 0x7f83e809f700 (LWP 8630)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        43 Thread 0x7f83e807d700 (LWP 8631)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        42 Thread 0x7f83e805b700 (LWP 8632)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        41 Thread 0x7f83e8039700 (LWP 8633)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        40 Thread 0x7f83e8017700 (LWP 8634)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        39 Thread 0x7f83e7ff5700 (LWP 8635)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        38 Thread 0x7f83e7fd3700 (LWP 8636)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        37 Thread 0x7f83e7fb1700 (LWP 8637)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        36 Thread 0x7f83e7f8f700 (LWP 8638)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        35 Thread 0x7f83e7f6d700 (LWP 8639)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        34 Thread 0x7f83e7f4b700 (LWP 8640)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        33 Thread 0x7f83e7f29700 (LWP 8641)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        32 Thread 0x7f83e7f07700 (LWP 8642)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        31 Thread 0x7f83e7ee5700 (LWP 8643)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        30 Thread 0x7f83e7ec3700 (LWP 8644)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        29 Thread 0x7f83e7ea1700 (LWP 8645)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        28 Thread 0x7f83e7e7f700 (LWP 8646)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        27 Thread 0x7f83d7c5a700 (LWP 8647)  0x00007f83ea6db09d in
>>>>>>>>>> waitpid
>>>>>>>>>> () from /lib64/libpthread.so.0
>>>>>>>>>>        26 Thread 0x7f83d7c53700 (LWP 8648)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        25 Thread 0x7f83d7252700 (LWP 8649)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        24 Thread 0x7f83d6851700 (LWP 8650)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        23 Thread 0x7f83d5e50700 (LWP 8651)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        22 Thread 0x7f83d544f700 (LWP 8652)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        21 Thread 0x7f83d4a4e700 (LWP 8653)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        20 Thread 0x7f83d404d700 (LWP 8654)  0x00007f83ea20be7d in
>>>>>>>>>> write
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        19 Thread 0x7f83d364c700 (LWP 8655)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        18 Thread 0x7f83d2c4b700 (LWP 8656)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        17 Thread 0x7f83d224a700 (LWP 8657)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        16 Thread 0x7f83d1849700 (LWP 8658)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        15 Thread 0x7f83d0e48700 (LWP 8659)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        14 Thread 0x7f83d0447700 (LWP 8660)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        13 Thread 0x7f83cfa46700 (LWP 8661)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        12 Thread 0x7f83cf045700 (LWP 8662)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        11 Thread 0x7f83ce644700 (LWP 8663)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        10 Thread 0x7f83cdc43700 (LWP 8664)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> () from /lib64/libc.so.6
>>>>>>>>>>        9 Thread 0x7f83cd242700 (LWP 8665)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        8 Thread 0x7f83cc841700 (LWP 8666)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        7 Thread 0x7f83cbe40700 (LWP 8667)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        6 Thread 0x7f83cb43f700 (LWP 8668)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        5 Thread 0x7f83caa3e700 (LWP 8669)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        4 Thread 0x7f83ca03d700 (LWP 8670)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        3 Thread 0x7f83c963c700 (LWP 8671)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>>        2 Thread 0x7f83c8c3b700 (LWP 8672)  0x00007f83ea215ae9 in
>>>>>>>>>> syscall
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>> * 1 Thread 0x7f83eb3a8700 (LWP 8597)  0x00007f83ea211d03 in select
>>>>>>>>>> ()
>>>>>>>>>> from /lib64/libc.so.6
>>>>>>>>>> (gdb)
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> (gdb) bt
>>>>>>>>>> #0  0x00007f83ea20be7d in write () from /lib64/libc.so.6
>>>>>>>>>> #1  0x00007f83ea1a2583 in _IO_new_file_write () from
>>>>>>>>>> /lib64/libc.so.6
>>>>>>>>>> #2  0x00007f83ea1a3b35 in _IO_new_do_write () from /lib64/libc.so.6
>>>>>>>>>> #3  0x00007f83ea1a21fd in _IO_new_file_xsputn () from
>>>>>>>>>> /lib64/libc.so.6
>>>>>>>>>> #4  0x00007f83ea17589d in vfprintf () from /lib64/libc.so.6
>>>>>>>>>> #5  0x00007f83ea18003a in printf () from /lib64/libc.so.6
>>>>>>>>>> #6  0x000000000058f0e8 in tcp_recv (desc=0x2c3d350, request_len=0)
>>>>>>>>>> at
>>>>>>>>>> drivers/common/inet_drv.c:8976
>>>>>>>>>> #7  0x000000000058f63a in tcp_inet_input (data=0x2c3d350,
>>>>>>>>>> event=<value
>>>>>>>>>> optimized out>) at drivers/common/inet_drv.c:9326
>>>>>>>>>> #8  tcp_inet_drv_input (data=0x2c3d350, event=<value optimized
>>>>>>>>>> out>)
>>>>>>>>>> at drivers/common/inet_drv.c:9604
>>>>>>>>>> #9  0x00000000004b770f in erts_port_task_execute
>>>>>>>>>> (runq=0x7f83e9d5d3c0,
>>>>>>>>>> curr_port_pp=0x7f83e8dc6e78) at beam/erl_port_task.c:851
>>>>>>>>>> #10 0x00000000004afd83 in schedule (p=<value optimized out>,
>>>>>>>>>> calls=<value optimized out>) at beam/erl_process.c:6533
>>>>>>>>>> #11 0x0000000000539ca2 in process_main () at beam/beam_emu.c:1268
>>>>>>>>>> #12 0x00000000004b1279 in sched_thread_func (vesdp=0x7f83e8dc6dc0)
>>>>>>>>>> at
>>>>>>>>>> beam/erl_process.c:4834
>>>>>>>>>> #13 0x00000000005bb3e6 in thr_wrapper (vtwd=0x7fffe8266da0) at
>>>>>>>>>> pthread/ethread.c:106
>>>>>>>>>> #14 0x00007f83ea6d3851 in start_thread () from
>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>> #15 0x00007f83ea21911d in clone () from /lib64/libc.so.6
>>>>>>>>>> (gdb)
>>>>>>>>>>
>>>>>>>>>> (gdb) bt
>>>>>>>>>> #0  0x00007f83ea6da54d in read () from /lib64/libpthread.so.0
>>>>>>>>>> #1  0x0000000000554b6e in signal_dispatcher_thread_func
>>>>>>>>>> (unused=<value
>>>>>>>>>> optimized out>) at sys/unix/sys.c:2776
>>>>>>>>>> #2  0x00000000005bb3e6 in thr_wrapper (vtwd=0x7fffe8266c80) at
>>>>>>>>>> pthread/ethread.c:106
>>>>>>>>>> #3  0x00007f83ea6d3851 in start_thread () from
>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>> #4  0x00007f83ea21911d in clone () from /lib64/libc.so.6
>>>>>>>>>> (gdb)
>>>>>>>>>>
>>>>>>>>>> (gdb) bt
>>>>>>>>>> #0  0x00007f83ea215ae9 in syscall () from /lib64/libc.so.6
>>>>>>>>>> #1  0x00000000005bba35 in wait__ (e=0x2989390) at
>>>>>>>>>> pthread/ethr_event.c:92
>>>>>>>>>> #2  ethr_event_wait (e=0x2989390) at pthread/ethr_event.c:218
>>>>>>>>>> #3  0x00000000004ae5bd in erts_tse_wait (fcalls=<value optimized
>>>>>>>>>> out>,
>>>>>>>>>> esdp=0x7f83e8e2c440, rq=0x7f83e9d5e7c0) at beam/erl_threads.h:2319
>>>>>>>>>> #4  scheduler_wait (fcalls=<value optimized out>,
>>>>>>>>>> esdp=0x7f83e8e2c440,
>>>>>>>>>> rq=0x7f83e9d5e7c0) at beam/erl_process.c:2087
>>>>>>>>>> #5  0x00000000004afb94 in schedule (p=<value optimized out>,
>>>>>>>>>> calls=<value optimized out>) at beam/erl_process.c:6467
>>>>>>>>>> #6  0x0000000000539ca2 in process_main () at beam/beam_emu.c:1268
>>>>>>>>>> #7  0x00000000004b1279 in sched_thread_func (vesdp=0x7f83e8e2c440)
>>>>>>>>>> at
>>>>>>>>>> beam/erl_process.c:4834
>>>>>>>>>> #8  0x00000000005bb3e6 in thr_wrapper (vtwd=0x7fffe8266da0) at
>>>>>>>>>> pthread/ethread.c:106
>>>>>>>>>> #9  0x00007f83ea6d3851 in start_thread () from
>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>> #10 0x00007f83ea21911d in clone () from /lib64/libc.so.6
>>>>>>>>>> (gdb)
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> (gdb) bt
>>>>>>>>>> #0  0x00007f83ea6db09d in waitpid () from /lib64/libpthread.so.0
>>>>>>>>>> #1  0x0000000000555a9f in child_waiter (unused=<value optimized
>>>>>>>>>> out>)
>>>>>>>>>> at sys/unix/sys.c:2700
>>>>>>>>>> #2  0x00000000005bb3e6 in thr_wrapper (vtwd=0x7fffe8266d50) at
>>>>>>>>>> pthread/ethread.c:106
>>>>>>>>>> #3  0x00007f83ea6d3851 in start_thread () from
>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>> #4  0x00007f83ea21911d in clone () from /lib64/libc.so.6
>>>>>>>>>> (gdb)
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> **** END UPDATE ****
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I'm happy to provide any information I can, so please don't
>>>>>>>>>> hesitate
>>>>>>>>>> to
>>>>>>>>>> ask.
>>>>>>>>>>
>>>>>>>>>> Thanks in advance!
>>>>>>>>>>
>>>>>>>>>> Kind Regards,
>>>>>>>>>>
>>>>>>>>>> Peter Membrey
>>>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> erlang-bugs mailing list
>>>>>>>> 
>>>>>>>> http://erlang.org/mailman/listinfo/erlang-bugs
>>>>>>



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