[zeromq-dev] Race condition in tcp_socket_t

[Martin Sustrik]

Christian,

A sanity check: How many I/O threads are you usign? (parameter to 
zmq_init function).

Martin

On 11/12/2010 06:17 PM, Christian Gudrian wrote:
> Am 12.11.2010 17:32, schrieb Martin Sustrik:
>
>    
>> Can you possibly get the backtraces for the two threads accessing the
>> same tcp_socket_t the in parallel?
>>      
> That's a tough one. Apart from C++Builder not being able to copy stack
> traces to the clipboard it's quite hard to make the threads stop at the
> right time to get a usable trace.
>
> I've instrumented tcp_socket_t so that it records
>
> 1. which thread called open()
> 2. which thread called close()
> 3. which thread called write()
>
> I've added assertions and tweaked abort() so that it puts the process
> into an endless loop rather than terminate it.
>
> This is the call stack of thread 3024 which called the close method on a
> tcp_socket_t instance which got opened by thread 8212:
>
> http://dl.dropbox.com/u/9848985/zeromq/zmq-1.png
>
> That thread (8212) was also the last one to call the write method on
> that particular instance. Currently that threat waits for the Winsock
> select function to return. It's current call stack is of no use.
>
> This is the call stack of thread 8348 which called the close method on a
> tcp_socket_t instance it also opened, but which got written to by thread
> 9348:
>
> http://dl.dropbox.com/u/9848985/zeromq/zmq-2.png
>
> Thread 9348, however, just called the close method on a tcp_socket_t
> instance that got opened by thread 6708:
>
> http://dl.dropbox.com/u/9848985/zeromq/zmq-3.png
>
> And thread 6708 just called the close method on a tcp_socket_t instance
> it opened itself, but which got written to by thread 8444:
>
> http://dl.dropbox.com/u/9848985/zeromq/zmq-4.png
>
> That is as close as I could get to the heart of the matter.
>
> HTH,
>
> Christian
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