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

Patrik Nyblom <>
Thu Nov 29 19:46:20 CET 2012


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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