CODEWITHSUNDEEP
c++multithreadingconcurrencyparallel-processingpthreads
user2889419
user2889419

Reputation:

Get threads are held for locking a mutex

I just wondered how would I get(count) the threads are held for locking a mutex, for example considering the following example

void _foo(void* arg){
pthread_mutex_lock(&_lock);//[ABC]
//doing something
pthread_mutex_unlock(&_lock);
}

so the question: how would I find out how many threads are currently waiting to get lock the _lock at [ABC] in pthread? or any other parallel lib.

and a little more confusing question, is it possible to redirect the waiting threads to somewhere else? for example just after the first thread process, waiting threads will be redirected to _bar() method, I mean change the code execution at runtime.

Upvotes: 0

Views: 79

Answers (2)

alk
alk

Reputation: 70911

1st question: Count them up, before letting them run into the lock. Count them down after having left the locked state.

2nd question: Look at pthread_mutex_trylock() Depending on its result (EBUSY or not) continue with foo() or call bar().

Upvotes: 1

NPE
NPE

Reputation: 500267

I don't think there's a standard pthreads way to get the count of waiting threads.

As to the second question, you could use pthread_mutex_trylock().

Upvotes: 1

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