boost::mutex question

8 Feb 2007

      Hi all!

I'm curious about the realization of the boost::mutex class (especially 
on W32).

* How heavy is it to create a mutex object?

* Are there any limits (OS recource bound or other) to how many mutex 
object that can be created?

* How costly is it to 're-lock' a recursive mutex? Almost NOP or more 
costly?

Are these questions (and other of the same type) answered somewhere in 
the docs?

Finally, a more concrete question. Consider the following:

A list of objects that needs to lock a mutex (all lock the same mutex).

vector foo;
...
for ( ... i = each foo ... )
   i->doWorkThatLocks();

This code section will lock/unlock repeatedly.

If I use a recursive mutex, will the following be much faster (since the 
locks in 'doWorkThatLocks' will be more light-weight)?

lock();
for ( ... i = each foo ... )
   i->doWorkThatLocks();
unlock();

Best Regards
Anders Sundman

Anders Sundman