Name: krC82822 Date: 11/09/2000


D:\tmp>/usr/local/Java/jdk1.3/bin/java -version
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)

The thread dump produced when running with hotspot does not produce a
monitor cache dump table to associate the monitors with objects. The
thread dump produced when using the -classic argument is very useful.
The thread dump produced when running with hotspot is minimally useful.
Compare the two using the following simple program and you can see that
the classic thread dump clearly illustrates why the program is hanging.
The hotspot thread dump does not show this. You have to look at the code
for each stack trace to try to figure out what the state of the vm is.
Why can't the same information be provied in both cases?


D:\tmp>type tstDump.java
class tstDump implements Runnable
{
        Thread t0, t1;
        tstDump()
        {
                t0 = new Thread(this, "T0");
                t0.start();
                t1 = new Thread(this, "T1");
                t1.start();
        }

        public synchronized void run()
        {
                Thread t = Thread.currentThread();
                System.out.println(t+", begin run");
                try
                {
                        synchronized( t )
                        {
                                t.wait();
                        }
                        notify();
                }
                catch(InterruptedException e)
                {
                }
                System.out.println(t+", end run");
        }
        public static void main(String[] args) throws Exception
        {
                tstDump tst = new tstDump();
                synchronized( tst )
                {
                        tst.wait();
                }
        }
}

D:\tmp>/usr/local/Java/jdk1.3/bin/java tstDump
Thread[T0,5,main], begin run
Full thread dump:

"T1" prio=5 tid=0x8ae6f8 nid=0x6b0 runnable [0x8eaf000..0x8eafdc4]
        at tstDump.run(tstDump.java:14)
        at java.lang.Thread.run(Thread.java:484)

"T0" prio=5 tid=0x803628 nid=0x598 waiting on monitor [0x8e6f000..0x8e6fdc4]
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:420)
        at tstDump.run(tstDump.java:20)
        at java.lang.Thread.run(Thread.java:484)

"Signal Dispatcher" daemon prio=10 tid=0x7ebad0 nid=0x85c waiting on monitor
[0..0]

"Finalizer" daemon prio=9 tid=0x7e9238 nid=0x740 waiting on monitor
[0x8c4f000..0x8c4fdc4]
        at java.lang.Object.wait(Native Method)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:108)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:123)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:162)

"Reference Handler" daemon prio=10 tid=0x7e7a18 nid=0x62c waiting on monitor
[0x8c0f000..0x8c0fdc4]
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:420)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:110)

"main" prio=5 tid=0x234288 nid=0x5c8 initialized [0x6f000..0x6fc3c]
        at tstDump.main(tstDump.java:34)

"VM Thread" prio=5 tid=0x89900e0 nid=0x1f8 runnable

"VM Periodic Task Thread" prio=10 tid=0x7eb1e8 nid=0x34c waiting on monitor

D:\tmp>/usr/local/Java/jdk1.3/bin/java -classic tstDump
Thread[T0,5,main], begin run

Full thread dump Classic VM (1.3.0-C, native threads):
    "T1" (TID:0x143ec68, sys_thread_t:0x4ad01b8, state:MW, native ID:0x34c)
prio=5
        at java.lang.Thread.run(Thread.java:484)
    "T0" (TID:0x143ec00, sys_thread_t:0x4ad00d0, state:CW, native ID:0x740)
prio=5
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:420)
        at tstDump.run(tstDump.java:20)
        at java.lang.Thread.run(Thread.java:484)
    "Finalizer" (TID:0x1449528, sys_thread_t:0x48f8bc0, state:CW, native
ID:0x62c) prio=8
        at java.lang.Object.wait(Native Method)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:108)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:123)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:162)
    "Reference Handler" (TID:0x1449300, sys_thread_t:0x48f4b70, state:CW,
native ID:0x1f8) prio=10
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:420)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:110)
    "Signal dispatcher" (TID:0x1449330, sys_thread_t:0x48ee518, state:R,
nativeID:0x85c) prio=5
    "main" (TID:0x14491a0, sys_thread_t:0x233c08, state:CW, native ID:0x598)
prio=5
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:420)
        at tstDump.main(tstDump.java:34)
Monitor Cache Dump:
    java.lang.Thread@143EC00/15AD3B8: <unowned>
        Waiting to be notified:
            "T0" (0x4ad00d0)
    java.lang.ref.ReferenceQueue$Lock@1449540/147F420: <unowned>
        Waiting to be notified:
            "Finalizer" (0x48f8bc0)
    java.lang.ref.Reference$Lock@1449310/147EF40: <unowned>
        Waiting to be notified:
            "Reference Handler" (0x48f4b70)
    tstDump@143EBF8/15AD3A8: owner "T0" (0x4ad00d0) 1 entry
        Waiting to enter:
            "T1" (0x4ad01b8)
        Waiting to be notified:
            "main" (0x233c08)
Registered Monitor Dump:
    utf8 hash table: <unowned>
    JNI pinning lock: <unowned>
    JNI global reference lock: <unowned>
    BinClass lock: <unowned>
    Class linking lock: <unowned>
    System class loader lock: <unowned>
    Code rewrite lock: <unowned>
    Heap lock: <unowned>
    Monitor cache lock: owner "Signal dispatcher" (0x48ee518) 1 entry
    Thread queue lock: owner "Signal dispatcher" (0x48ee518) 1 entry
    Monitor registry: owner "Signal dispatcher" (0x48ee518) 1 entry
(Review ID: 112061)
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