[zeromq-dev] libzmq and helgrind

Michi Henning michi at triodia.com
Mon Aug 18 23:28:02 CEST 2014

Hi Thomas,

thanks for the quick answer!

> If the message size exceeds the 'vsm' message length limit, it becomes an 'lmsg'.  This type is indeed heap allocated, and when the enclosing message type is copied, the copies share the reference to the underlying heap allocation (and any potential data races that come along with that).  The lifetime is controlled by an atomic refcount.
>  zmq::msg_t::close() should not create a race as it relies on the atomic refcount dropping to zero before freeing the heap block.  
> Access to the actual message data() could potentially create a data race, but the receiving side should never have access to a message that is still being written by a background thread.

OK, so that sounds like the races on data() and memcpy() are bogus. What about the close() race though? I wasn't expecting to see that one.



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