Runtime.getRuntime().exec(...) -> Java process hangs in STOP state

[Thomas Lange]

Hi everyone,

has anybody experienced a similar problem?

I'm running tomcat with an apache / mod_jk frontend.

After running a few days under medium load, a call of
Runtime.getRuntime().exec(...) will not return. Also the Java process will
hang infinitely in a STOP state (as displayed by  top).

As a result, mbufs or other resources will fill up until the entire server
runs out of resources and hangs (creation of new processes is not possible
anymore).

I'm using FreeBSD 5.3-RELEASE-p5, jdk1.4, patchset 7. Everything (including
the kernel) is compiled with -O2.

Checking the output of my programm shows, that all processes created by it
terminate correctly (that is, all but the last).

In an ealier version (FreeBSD 4.9-RELEASE-p4), jdk1.4, patchset 6 there is a
similar problem. Here calling Runtime.getRuntime().exec(...) results in
creating a very high CPU load and not returning from the exec() call.

My applications calls the exec()-method once every few minutes.

Might it even be a threading issue?

I've included a snippet from my program as an attachment.

Any comments or suggestions are welcome!

Regards
Thomas



public static boolean executeCommand(String exCommand, int exTimeout) {
    String command = "nice -n 15 ";
    command = command + exCommand;
    Process process = null;

    try {
        System.out.println("Executing external command " + command);
        process = Runtime.getRuntime().exec(command);
    }
    catch (IOException e) {
        System.out.println(e.toString());
        return false;
    }

    InputStream inputStream = process.getInputStream();
    BufferedInputStream bufferedInputStream = new
BufferedInputStream(inputStream);
    InputStream errorStream = process.getErrorStream();
    BufferedInputStream bufferedErrorStream = new
BufferedInputStream(errorStream);
    boolean ok = false;
    int timeout = exTimeout;
    int exitValue = -999;

    while (!ok) {
        try {
            while (bufferedInputStream.available() > 0 ||
bufferedErrorStream.available() > 0) {
                while (bufferedInputStream.available() > 0) {
                    System.out.print((char)bufferedInputStream.read());
                }
                while (bufferedErrorStream.available() > 0) {
                    System.out.print((char)bufferedErrorStream.read());
                }
            }
        }
        catch (IOException e) {
            System.out.println("Couldn't read response");
        }
        try {
            exitValue = process.exitValue();
            ok = true;
        }
        catch (IllegalThreadStateException e) {
            try {
                // still running.
                Thread.sleep(300);
                timeout = timeout - 300;
                if (timeout < 0 && timeout >= -300) {
                    System.out.println("ALERT: Command doesn't terminate:");
                    System.out.println(command);
                    System.out.println("Shutting down command...");
                    process.destroy();
                }
                else if (timeout <0) {
                    System.out.println("ALERT: Command STILL doesn't
terminate:");
                    System.out.println(command);
                    Thread.sleep(1000);
                }
            } catch (InterruptedException e1) {
                // doesn't matter
            }
        }
    }
    if (ok) {
        // finished running
        if (exitValue == 0) {
            System.out.println("Terminated without errors");
        }
        else {
            System.out.println("Exit code " + exitValue + " while performing
command " + command);
        }
    }
    else {
        process.destroy();
    }
    try {
        while (bufferedInputStream.available() > 0) {
            System.out.print((char)bufferedInputStream.read());
        }
        while (bufferedErrorStream.available() > 0) {
            System.out.print((char)bufferedErrorStream.read());
        }
    }
    catch (IOException e) {
        System.out.println("Couldn't read response");
    }
    return exitValue == 0;
}