Re: [boost] [thread] best practice to lock multiple mutexes

From: Anthony Williams (anthony_w.geo_at_[hidden])
Date: 2008-02-08 14:42:32

Howard Hinnant <hinnant <at> twcny.rr.com> writes:

> template <class L1, class L2>
> void
> lock(L1& l1, L2& l2)
> {
>      while (true)
>      {
>          {
>          unique_lock<L1> __u1(l1);
>          if (l2.try_lock())
>          {
>              __u1.release();
>              break;
>          }
>          }
>          std::this_thread::yield();

snipped rest of multi-lock code.

> 3.  The yields are absolutely necessary to get the high performance  
> mentioned in the previous note.

I find this comment intriguing. Is this always the case, or does it depend on
the specifics of how a mutex is implemented on a given platform?

Anthony