Re: [Boost-users] Shared mutex vs normal mutex

Bump Sent from my iPhone On Aug 25, 2009, at 7:27 AM, Alessandro Bellina wrote:

Hello I am testing the boost mutex/lock classes in order to implement a multiple reader single writer model.

Because of this I thought that the shared mutex with lock_shared and lock_unique would be perfect. I'm finding that the performance is no better than with a simple mutex.

My writer is adding a bunch of elements, locking the shared container exclusivelly until it is done. The readers looks at all elements of the container, locking on a per element basis.

Any ideas as to why the shared mutex would be slower in this case than the simple mutex?

This is the code for my producer thread and my consumers (as a side note, employee_set is a multi index):

typedef boost::shared_mutex mutex_type; typedef boost::shared_lock read_lock_type; typedef boost::unique_lock write_lock_type;

static mutex_type rw_mutex;

struct ConsumerThread{ ConsumerThread (employee_set* e):es(e){}

void operator()(){

for (int i=0; i<es->size(); i++){ read_lock_type l(rw_mutex); es->get<1>(); }

}

employee_set* es;

};

struct ProducerThread{

ProducerThread(int n, employee_set* e):N(n),es(e){}

void operator()(){

write_lock_type l(rw_mutex); for (int i=0; iinsert (employee(i, "TestEmployee",100-i)); } l.unlock();

}

int N; employee_set* es;

};