hang in Lion (original) (raw)

Charles K Pepperdine kirk at kodewerk.com
Wed Nov 30 04:11:32 PST 2011

Hi,

I've got a chunk of code that mysteriously hangs on my new i7 Air running Lion. This code was given to me by a friend that is also running Lion. We've given it to another person that is also running Lion. I'm using 1.6.0_26-b02-383. It doesn't hang all the time and it doesn't hang on my older i7 17" MBP running Snow Leopard. It's also been tested on other MBP's running Snow Leopard without hanging. Forcing a core dump after the hang gave us this.

Thread 24: Java: Thread-1 0 libSystem.B.dylib 0x00007fff89f88d7a machmsgtrap + 10 1 libSystem.B.dylib 0x00007fff89f893ed machmsg + 59 2 libclient64.dylib 0x000000010100d903 jiosnprintf + 37641 3 libclient64.dylib 0x000000010100d7c3 jiosnprintf + 37321 4 libclient64.dylib 0x000000010100d722 jiosnprintf + 37160 5 libclient64.dylib 0x000000010100c5ad jiosnprintf + 32691 6 libclient64.dylib 0x000000010100c4ef jiosnprintf + 32501 7 libclient64.dylib 0x00000001011afefd JVMGetClassInterfaces + 12075 8 libclient64.dylib 0x00000001010a7c8c JVMLseek + 204251 9 libclient64.dylib 0x00000001010a7bea JVMLseek + 204089 10 libclient64.dylib 0x00000001011b4931 JVMSocket + 5319 11 ??? 0x000000010380f0e7 0 + 4353749223 12 ??? 0x000000010386fd90 0 + 4354145680

Thread 25: Java: Thread-2 0 libSystem.B.dylib 0x00007fff89f88d7a machmsgtrap + 10 1 libSystem.B.dylib 0x00007fff89f893ed machmsg + 59 2 libclient64.dylib 0x000000010100db03 jiosnprintf + 38153 3 libclient64.dylib 0x00000001010cb569 JVMWrite + 9130 4 libclient64.dylib 0x00000001011ddfcd JVMNanoTime + 39179 5 ??? 0x000000010386ea60 0 + 4354140768

All of the other thread could be attributed to VM processes (GC, compiler etc...).

On my machine, the hang seems to only happen when thread-2 finishes before thread-1. I've never seen it hang when thread-1 finishes before thread-2 Again it doesn't hang all the time when thread-2 finishes first. This is a hard hang in that I can only get rid of the process with a kill -9. ^C and kill simply don't to anything.

Code follows,

Regards, Kirk Pepperdine

public class Foo {

private int counter;

public static void main(String[] args) throws Exception {
    new Foo().run();
}

public void run() throws Exception {

    Thread[] threads = new Thread[2];

    for (int i = 0; i < threads.length; i++) {
        threads[i] = new Thread() {
            public void run() {

                System.out.println("Thread started " + Thread.currentThread().getName());
                System.out.flush();

                for (int i = 0; i < 100000; i++) {
                    increment();
                }

                System.out.println("Thread done " + Thread.currentThread().getName());
                System.out.flush();
            }
        };
    }

    for (Thread t : threads) {
        t.start();
    }

    System.out.println("Started");
    System.out.flush();

    System.out.println("Awaiting complete...");
    System.out.flush();

    for (Thread t : threads) {
        t.join();
    }

    System.out.println("Completed...");
    System.out.flush();
}

private synchronized void increment() {

    counter++;

    if (counter % 10000 == 0) {
        System.out.printf("%s: %d\n", Thread.currentThread().getName(), counter);
        System.out.flush();
    }
}

}

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