CODEWITHSUNDEEP
c++multithreadingboostmutexboost-mutex
Jason Harrison
Jason Harrison

Reputation: 965

Do all threads in boost::thread_group share the same thread with respect to boost::recursive_mutex

I suspect that based on the behavior of my code that if I have a boost::thread_group accessing an object protected by a boost::recursive_mutex that the mutex does not prevent threads from within the group from simultaneously entering the protected area.

This is confusing because I see all of the threads listed in the debugger (xcode).

Is this a known issue? I couldn't find any documentation on it.

Upvotes: 1

Views: 148

Answers (1)

sehe
sehe

Reputation: 392911

A boost thread_group is a group of threads.

All the threads are, by definition, distinct and unique.

So, if your mutex fails to... "mut-ex" (mutually exclude) this indicates a programmer error elsewhere.

On a whim, I'd suggest that perhaps your expectations of mutexes (recursive or not) is not accurate (in similar way as the expectations of a thread group were)?

The thing you might have missed is that all parties accessing the shared objects /must/ acquire the mutex at all times of these accesses. It is not enough to have one thread "guard" the shared objects, to magically keep other threads out.

Mutexes are a coöperative proposition. The term "critical section" is actually a bit nicer in this respect: you "mark" the critical sections in code, as opposed to "marking" the critical data (whatever that would be).

Upvotes: 1

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