performance problem with process fork in gcj compiled CNI

Fri Jan 27 01:44:00 GMT 2006

performance problem with process fork in gcj compiled CNI
Hello,
 I have a simple C++ program with a main function that fork itself's 
process and then it starts a loop calling some processing in java compiled 
code, using CNI.
 I intend to split processing in a machine with 2 CPUs using fork 
technology, I'm not able to use another solution.
 When I run the program without forking, it takes about T seconds to 
finish consuming 100% of CPU and 50% of the machine.
 When I run the program with a fork in the beginning, it takes more than 
2T seconds to finish with each process consuming 100% of CPU and both 
consuming 100% of the machine.
 What's happening ?
Temporal.
#include <iostream>
#include <string>
#include <sys/types.h>
#include <unistd.h>
#include <gcj/cni.h>
#include <java/lang/Double.h>
#include <java/util/ArrayList.h>
using namespace std;
using namespace java::lang;
using namespace java::util;
int globalVariable = 2;
/*
	Code Templates:
	http://www-personal.umich.edu/~rusekd/articles/soc_prelim.html
	http://www.yolinux.com/TUTORIALS/ForkExecProcesses.html
*/
int	main(int argc, char **argv)
{
	if (argc != 3)
	{
		cerr << "usage: integer bool" << endl;
		return 1;
	}
	cout << "begin" << endl;
	JvCreateJavaVM(NULL);
	JvAttachCurrentThread(NULL, NULL);
 string sIdentifier;
 int iStackVariable = 20;
 pid_t pID = (atol(argv[2]) ? fork() : 1);
 if (pID == 0) // child
 {
 // Code only executed by child process
 sIdentifier = "Child Process: ";
 globalVariable++;
 iStackVariable++;
 }
 else if (pID < 0) // failed to fork
 {
 cerr << "Failed to fork" << endl;
 exit(1);
 // Throw exception
 }
 else // parent
 {
 // Code only executed by parent process
 sIdentifier = "Parent Process:";
 }
 // Code executed by both parent and child.
 cout << sIdentifier;
 cout << " Global variable: " << globalVariable;
 cout << " Stack variable: " << iStackVariable << endl;
	ArrayList	*arrayList = new ArrayList;
	int	loopSize = atol(argv[1]);
	int	maxArraySize = loopSize >> 3;
	for(int	i = 0, j = 0; i < loopSize; i++, j++)
	{
		arrayList->add(new Double((jdouble)(double)i));
		if (j == maxArraySize)
		{
			j = 0;
			jint	size = arrayList->size();
			arrayList->clear();
			cout << pID << ", clear from " << (int)size << " to " << 
(int)arrayList->size() << endl;
		}
	}
	JvDetachCurrentThread();
	cout << "end" << endl;
	return 0;
}