[boost] read_write_mutex fundamentally broken in 1.33?

From: John Maddock (john_at_[hidden])
Date: 2005-09-08 05:45:42

I've been trying to solve the deadlock problem reported here: 
http://lists.boost.org/Archives/boost/2005/08/92307.php  but I've simply run 
into more and more problems, and just about every operation I've tried will 
deadlock if you try hard enough.

THIS IS NOT GOOD.

Applying Roland Swartz's suggested fix everywhere that looked appropriate 
initially seemed to fix the issue, but once you move to more complex 
situations (both readers and writers) then the deadlocks simply come back 
again.  At this point I've exhausted my understanding of the problem and the 
design of the lock.  As an aside: it is *very* hard to implement something 
like this correctly: no amount of debugging will ever get you a reliable 
system, only a clearly understood design backed up by a solid theoretical 
understanding of the implementation method (formal methods anyone?).  To be 
honest I have to question whether it's even a good idea for this to be in 
Boost (no slur intended towards the implementers of that class, it's the 
difficulty of the problem that's the issue).

In case anyone wants to pursue this further I'm attaching my current test 
case, and the current patches I have to the implementation, however, please 
note that neither this test case, nor the current regression tests are 
anything like comprehensive, THEY WILL NOT CATCH ALL POSSIBLE PROBLEMS.

Sorry about the capital letters folks, but I suspect we have a "Huston, we 
have a problem" moment here :-(

Regards,

John.