[Boost-bugs] [Boost C++ Libraries] #4894: segmentation fault on thread_group::join_all depending on the machine used

Subject: [Boost-bugs] [Boost C++ Libraries] #4894: segmentation fault on thread_group::join_all depending on the machine used
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-11-25 08:31:00

#4894: segmentation fault on thread_group::join_all depending on the machine used
--------------------------------+-------------------------------------------
 Reporter:  lyxthe@…            |       Owner:         
     Type:  Bugs                |      Status:  new    
Milestone:  To Be Determined    |   Component:  None   
  Version:  Boost 1.35.0        |    Severity:  Problem
 Keywords:                      |  
--------------------------------+-------------------------------------------
 Hello I would like to submit this new ticket, hopping it is really a
 problem and not an error of my own.

 I explain the problem, I made this simple program (just after) and,
 depending on the machine where I execute it, it makes a segmentation fault
 or not. I would like to know if it is because of the computer used or if
 it is really a bug.

 The program :


 {{{
 #include <iostream>
 #include <boost/thread/thread.hpp>
 #include <boost/bind.hpp>

 using namespace std;
 const int thread_nbr=20;

 void fonct(int num){
         cout << "thread " << num << endl;
 }

 int main(){
         int i=0;
         int j=0;
         boost::thread_group groupe;
         for(i=0;i<5;i++){
                 cout << "beginning of loop " << i << ":" << endl;
                 for(j=1;j<thread_nbr;j++){
                         groupe.create_thread(boost::bind(fonct,j));
                 }
                 fonct(0);
                 cout << "after fonct" << endl;
                 cout << "waiting for join.all" << endl;
                 groupe.join_all();
                 cout << "after join.all" << endl << endl;
         }
         return 0;
 }
 }}}

 The trace when it works (I have tested it on five different computers, one
 with one core, one with two cores, two with four cores, one with twelve
 cores, it didn't work for the one with twelve and one with four) :

 {{{
 beginning of loop 0:
 thread 1
 thread 2
 thread 3
 thread 4
 thread 5
 thread 6
 thread 7
 thread 8
 thread 9
 thread 10
 thread 11
 thread 12
 thread 13
 thread 14
 thread 15
 thread 16
 thread 17
 thread 18
 thread 19
 thread 0
 after fonct
 waiting for join.all
 after join.all

 beginning of loop 1:
 thread 1
 thread 2
 thread 3
 thread 4
 thread 5
 thread 6
 thread 7
 thread 8
 thread 9
 thread 10
 thread 11
 thread 12
 thread 13
 thread 14
 thread 15
 thread 16
 thread 17
 thread 18
 thread 19
 thread 0
 after fonct
 waiting for join.all
 Segmentation fault
 }}}

 On the other situations it works until the end.

 If I put the "const int thread_nbr" to 4 instead of 20, it works on every
 machine I tried.

 Apparently the problem come from the thread_group::join_all() function.

 Could the thread_group make a problem on certain machines when the number
 of threads in the group is big ?

 I Have tested it with boost 1.35 and boost 1.42.

 Do you know where the problem can come from.

 Is it a known problem maybe already solved in newer version of boost?

 Thanks to care on my question, and sorry for my bad english.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4894>
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