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

Subject: Re: [Boost-users] Shared mutex vs normal mutex
From: Alessandro Bellina (abellina_at_[hidden])
Date: 2009-08-25 19:04:45

Bump

Sent from my iPhone

On Aug 25, 2009, at 7:27 AM, Alessandro Bellina <abellina_at_[hidden]>  
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<mutex_type> read_lock_type;
> typedef boost::unique_lock<mutex_type> 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; i<N; i++){	
> 			es->insert (employee(i, "TestEmployee",100-i));
> 		}
> 		l.unlock();
> 		
> 		
> 	}
> 	
> 	int N;
> 	employee_set* es;
> 		
> };
>
>