RE: Java app and Native Processes on Linux

[Lee_Xing]

Hi:

 

I'm trying to use two java threads t1 and t2, and each one uses exec() to start the same C native application.  It seems JVM (BlackDown 1.1.8 v1) never switches from t1 to t2.  The output looks like:

 

In thread t1: i = 0

In thread t1: i = 1

In thread t1: i = 2

      ...

 

I put suspend() inside method run(), but it couldn't stop t1 from running.  What I missed?

 

The attached C and java codes are real and can be compiled.

 

Thank you.

 

 

Lee

---------------------------------------------------------------------------

 

/*******************************************************
* C application source code
********************************************************/

#include <stdio.h>

 

int main(int argc, char* argv[])
{
    int i;

    for(i=0; i<1000; i++)
    {
       printf("In thread %s: i = %d\n", argv[1], i);
        fflush(stdout);
        sleep(1);
    }

 

    return 0;
}

=======================================

 

/*******************************************************
* java application source code
********************************************************/
import java.lang.*;
import java.io.*;

 

class communicate
{
    public static void main(String args[])
    {
        myThread t1 = new myThread("t1");
        myThread t2 = new myThread("t2");

 

        t1.run();
        t2.run();
    }
}

 

class myThread extends Thread
{
    String szThreadName;

 

    myThread(String szName)
    {
        super(szName);
        szThreadName = szName;
    }

 

    public void run()
    {
        Process proc_;
        int rc;
        char[] buf = new char[1024]; 
        File fileObj = new File("a.out");
        String fileName = fileObj.getAbsolutePath();
        String cmd[] = new String[2];
        cmd[0] = fileName;
        cmd[1] = szThreadName;

 

        try
        {
             System.out.println("the executable name is:"+fileName);
             proc_ = Runtime.getRuntime().exec(cmd);
             BufferedReader in = new BufferedReader(new InputStreamReader(proc_.getInputStream()));

             do
             {
                 rc = in.read(buf);

                 if(rc>0)
                      System.out.print(buf);
     
                 suspend();  // why this suspend() doesn't work???
             }while(rc != -1);
         }
         catch(IOException e)
         {
            System.out.println("got e after try exec()");
            e.printStackTrace();
         }
    } // end of run()
} // end of myThread class