[Boost-users] [1.48] interprocess consumes 100% on 32bit Windows systems

Subject: [Boost-users] [1.48] interprocess consumes 100% on 32bit Windows systems
From: Bogdan Slusarczyk (bogdan.slusarczyk_at_[hidden])
Date: 2012-07-13 04:39:17

Hi All,

I found such problem:

N+1 (where N is number of cpu cores) processes with interprocess syncing use 100% cpu on 32 bit Windows system.

Cause of bug:

https://svn.boost.org/trac/boost/changeset/74110

void sched_yield()
-{  Sleep(1);   }
+{
+   if(!SwitchToThread()){
+      Sleep(1);
+   }

Test case:

#include <windows.h>
#include <iostream>
int main() {
     int i = 0;
     while( true ) {
         if ( !SwitchToThread() ) {
             std::cout << "sleep" << i++ << std::endl;
             Sleep(1); }
     }
}

On 32 bit windows system running this in N+1 separate processes will stop printing and use 100% CPU.

On 64 bit system for any number of processes printing will not stop.

Kind regards,
Bogdan