[Boost-users] [Threads] How to keep number of running thread constant, performing different operations

17 Jun 2011

      I have a problem in organizing concurrent thread launch. My program 
structure is the following:
#include <iostream>
#include <boost/thread.hpp>

using namespace std;

class Worker
{
     private:
         boost::thread m_Thread;

     public:
         Worker() { /* the thread is not-a-thread until we call start() */ }

         void start(int N) { m_Thread = 
boost::thread(&Worker::processQueue, this, N); }

         void join() { m_Thread.join(); }

         void processQueue(unsigned N) { /* Do some long long stuff... */ }
};

int main(int argc, char* argv[])
{
     Worker worker_1,
            worker_2,
            worker_3,
            worker_4;

     // How to start threads and join them in order
     // to make constantly two of them running?

     return 0;
}

I have different threads which have to work on completely different 
input and output data (non critical sections): an atomic operation per 
thread, each one with different time execution but everyone with an 
intense use of the CPU.
Let's say I have 10 operations to perform (10 threads): I would like to 
run concurrently only 2 threads because of resource consumption.

My problem is that when a threads ends its execution, I would like to 
suddenly start another thread performing operation 3, in order to have 
constantly 2 threads working, and so on until the end of operations.

How can I achieve this? I thought to insert my threads into a 
vector...but I have no idea on how start and join them in order to 
obtain what described above.

Can anyone post me a little example?

Thanks in advance.

-- 
Alessandro Candini

MEEO S.r.l.
Via Saragat 9
I-44122 Ferrara, Italy
Tel: +39 0532 1861501
Fax: +39 0532 1861637
http://www.meeo.it

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