[CppAD] Posix Threads with CppAD

[Brad Bell]

I am looking into extending CppAD to have a more general multi-threading 
interface that is tested with both OpenMP and pthreads.

On 8/11/2011 11:17 AM, Dominik Skanda wrote:
> Hello,
>
> I have also the needs to use CppAD utilizing Posix Threads.
> On the first view it seems to work for me and I don't get any
> segmentation faults but if I use "valgrind --tool=drd ./a.out" a tool
> for detecting errors in multithreaded C and C++ programs, valgrind
> complains sometimes.
> In summery I think that the memory assignment operations within a ADFun
> object are not thread save but if no memory gets allocated it seems
> running fine using Posix Threads.
> I have made a small as possible example and appended it further below. I
> compiled the example with "g++ -g main.cpp -I./ -lpthread".
> It would be gorgeous if the ADFun Object itself would be thread safe
> this specially means I think that extending the Taylor Capacity should
> be thread safe and the Copy operator, too.
> Many thanks and kind regards
>
> Dominik
>
>
> CODE:
>
> #include<pthread.h>
> #include<iostream>
> #include<vector>
> #include<cppad/cppad.hpp>
> using namespace std;
>
> pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
>
>
>
> struct THREAD_DATA{
> 	CppAD::ADFun<double>  fun;
> 	int threadNumber;
> };
>
>   void *start_CppAD(void *data)
> {
> 	int loop=1000;
> 	vector<  double>  x(2);
> 	x[0]=3.78;
>      x[1]=7.33;
>
>      int i;
>
>      vector<  double>  y(1);
> 	y[0]=0.0;
>
>      for (i=0;i<loop;i++)
> 		{
>
> 			y=((THREAD_DATA*)data)->fun.Forward(0,x);
> 			
> 			
> 			pthread_mutex_lock(&mutex);
> 			cout<<  i<<  " THREAD: "<<  ((THREAD_DATA*)data)->  threadNumber<<  "
> RESULT FORWARD 0: "<<  y[0]<<  endl;
> 			pthread_mutex_unlock(&mutex);
>
> 		}
>
>
> 	for (i=0;i<loop;i++)
> 		{
> 			y=((THREAD_DATA*)data)->fun.Forward(1,x);
>              ((THREAD_DATA*)data)->fun.capacity_taylor(1);
>
> 			pthread_mutex_lock(&mutex);
> 			cout<<  i<<  "THREAD: "<<  ((THREAD_DATA*)data)->  threadNumber<<  "
> RESULT FORWARD 1: "<<  y[0]<<  endl;
> 			pthread_mutex_unlock(&mutex);
> 			
> 		}
>
>
>
>
>      CppAD::ADFun<double>  copyFun;
>      copyFun=((THREAD_DATA*)data)->fun;
>
>      y=copyFun.Forward(0,x);
>
>      pthread_mutex_lock(&mutex);
>      cout<<  "THREAD: "<<  ((THREAD_DATA*)data)->  threadNumber<<  "
> RESULT COPY FUN FORWARD 0: "<<  y[0]<<  endl;
>      pthread_mutex_unlock(&mutex);
>
>      y=copyFun.Forward(1,x);
>
>      pthread_mutex_lock(&mutex);
>      cout<<  "THREAD: "<<  ((THREAD_DATA*)data)->  threadNumber<<  "
> RESULT COPY FUN FORWARD 1: "<<  y[0]<<  endl;
>      pthread_mutex_unlock(&mutex);
>
> 	return NULL;
> }
>
>
>
> int main (int argc, char *argv[])
> {
>    vector<  CppAD::AD<double>  >  x(2);
>    x[0]=3.78;
>    x[1]=7.33;
>    CppAD::Independent(x);
>    vector<  CppAD::AD<double>  >  y(1);
>    y[0]=sin(x[0])+cos(x[1]);
>
>    CppAD::ADFun<double>  fun(x, y);
>    fun.optimize();
>
>    vector<  double>  y_eval_1(1);
>    vector<  double>  x_eval_1(2);
>
>    x_eval_1[0]=3.78;
>    x_eval_1[1]=7.33;
>
>    y_eval_1=fun.Forward(0,x_eval_1);
>    fun.Forward(1,x_eval_1);
>
>    cout<<  "MAIN FUNCTION:"<<  "RESULT FORWARD 0: "<<  y_eval_1[0]<<
> endl;
>
>    struct THREAD_DATA dataThread1, dataThread2;
>
>    dataThread1.fun=fun;
>    dataThread1.threadNumber=1;
>    dataThread2.fun=fun;
>    dataThread2.threadNumber=2;
>
>    pthread_t executionThread[2];
>
>    int status;
>
>    status=pthread_create
> (&(executionThread[0]),NULL,start_CppAD,&dataThread1);
>    status=pthread_create
> (&(executionThread[1]),NULL,start_CppAD,&dataThread2);
>
>
>    status=pthread_join((executionThread[0]),NULL);
>    status=pthread_join((executionThread[1]),NULL);
>
>
>     return 0;
> }
>
>
>
>
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