Re: Multi threading / synchronization object

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 27 Jun 2007 18:23:13 -0400

Message-ID:

<R-2dncS3_NHIfh_bnZ2dnUVZ_gmdnZ2d@comcast.com>

Rinu Gopalakrishna Pillai wrote:

Hi,

I have a library as a dll and I need to load this in multi threaded
application .(More than one thread in a process and more than one process).

How can I snchronize the comman resources among thread and process( ie data
base, shared memory etc).

Which synchroniztion method should I use and why should I use that(
Mutex,Semaphore,Event or Critical section.)

If any one can tell which is the best and why , it will be highly appreciated.

To grant synchronized, exclusive access to a shared resource you can use
a mutex or a critical section. A critical section is generally more
efficient (runs faster when no contention), but it cannot be used by
multiple processes. A mutex can be used by multiple processes. So use
a CS if only one process accesses a resource, use a mutex if multiple
processes must do so.

The semaphore's purpose is to grant nonexclusive access to a limited
number of threads. So if N > 1 it does not provide thread safety.

The event is a signaling object, not a synchronization object.

--
Scott McPhillips [MVP VC++]