[zeromq-dev] Mac OS X: test_shutdown_stress sometimes fails

[Martin Sustrik]

Dhammika,

> I donno, may be we should simplify this.
> Why don't we add a refcount?

As a quick workaround -- yes. Do you have a patch for that kind of solution?

However, thinking about it conceptually, the problem is more generic. 
Namely, object A can call object B which in turn calls object A. In such 
a scenario, the inner call on A works on inconsistent state as the outer 
call isn't yet completed. Other way round, outer call on A gets the 
state changed underneath its feet when it calls B (see seq1.png attached).

The real solution, IMO, would be to use events to sequence actions on 
individual objects. That way there won't be inner and outer call, 
rather, there will be two event handlers executed one after another (see 
seq2.png).

Brief code review of 0MQ shows that this kind of problem only happens 
within a cluster of object composed of session, engine and 
decoder/encoder. The rest of the system (sockets, pipes) is using events 
already and doesn't have to be changed.

Martin
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