[zeromq-dev] race condition in pipe?

Martin Sustrik sustrik at fastmq.com
Mon Apr 13 07:17:02 CEST 2009

Hi Dhammika,

> writer_terminated in pipe sends term_ack to other thread and proceeds
> to reset pointers.
> However, on receiving term_ack api_thread deletes the pipe in
> terminate_pipe_ack (in engine_base.hpp)
> I think its possible to have a race condition here, and
> writer_terminated to could actually endup writing to deallocated
> memory.

This is probably the most complex part of the code. I've uploaded some 
sequence diagrams here:


I believe that writer_terminated gets called before reader_terminated 
(deallocation of the pipe) in all cases.

Still, if you've found a race condition, write down exact sequence of 
steps that causes the problem. We can start looking for the solution then.


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