2018-07-22 period Java deadlock small case programming

1. Deadlock Cases

public class DeadLock {

Final Object Locka = new Object ();

public static void Main (string[] args) {

DeadLock demo = new DeadLock ();

Demo.startlock ();

}

public void Startlock () {

Threada a = new Threada (Locka, lockb);

THREADB B = new threadb (Locka, lockb);

A.start ();

B.start ();

}

}

Class Threada extends Thread {

Private Object locka = null;

Private Object lockb = null;

Public Threada (Object A, object B) {

This.locka = A;

THIS.LOCKB = b;

}

public void Run () {

Synchronized (Locka) {

SYSTEM.OUT.PRINTLN ("----Thread a:locked A");

try {

Sleep (3000);

} catch (Interruptedexception e) {

E.printstacktrace ();

}

Synchronized (LOCKB) {

SYSTEM.OUT.PRINTLN ("----Thread a:locked B");

}

}

SYSTEM.OUT.PRINTLN ("----Thread a:finished");

}

}

Class Threadb extends Thread {

Private Object locka = null;

Private Object lockb = null;

Public Threadb (Object A, object B) {

This.locka = A;

THIS.LOCKB = b;

}

public void Run () {

Synchronized (LOCKB) {

SYSTEM.OUT.PRINTLN ("----Thread b:locked B");

try {

Sleep (3000);

} catch (Interruptedexception e) {

E.printstacktrace ();

}

Synchronized (Locka) {

System.out.println ("Tread b:locked A");

}

}

SYSTEM.OUT.PRINTLN ("----Thread b:finished");

}

}

2. Deadlock Analysis

Print Thread Dump

Linux environment kill-3 PID or Jstack

Windows environment ctrl+fn+b

The dump information is as follows:

D:\test\deadlock>java deadlock

----Thread a:locked A

----Thread b:locked B

2018-07-14 17:45:52

Full thread dump Java HotSpot (TM) Client VM (24.65-b04 mixed mode, sharing):

"DESTROYJAVAVM" prio=6 tid=0x02c4bc00 nid=0x1548 waiting on condition [0x00000000]

Java.lang.Thread.State:RUNNABLE

"Thread-1" prio=6 tid=0x02d2b400 nid=0x2b24 waiting for monitor entry [0x054bf000]

Java.lang.Thread.State:BLOCKED (on object monitor)

At Threadb.run (deadlock.java:64)

-Waiting to lock <0x252811c0> (a java.lang.Object)

-Locked <0x252811c8> (a java.lang.Object)

"Thread-0" prio=6 tid=0x02d2ac00 nid=0x3640 waiting for monitor entry [0x0542f000]

Java.lang.Thread.State:BLOCKED (on object monitor)

At Threada.run (deadlock.java:37)

-Waiting to lock <0x252811c8> (a java.lang.Object)

-Locked <0x252811c0> (a java.lang.Object)

"Service Thread" daemon prio=6 tid=0x02cdd800 nid=0x4138 runnable [0x00000000]

Java.lang.Thread.State:RUNNABLE

"C1 CompilerThread0" daemon prio=10 tid=0x02cdc800 nid=0x2324 waiting on condition [0x00000000]

Java.lang.Thread.State:RUNNABLE

"Attach Listener" daemon prio=10 tid=0x02cdac00 nid=0x22dc runnable [0x00000000]

Java.lang.Thread.State:RUNNABLE

"Signal Dispatcher" daemon prio=10 tid=0x02d04800 nid=0x2fb0 waiting on condition [0x00000000]

Java.lang.Thread.State:RUNNABLE

"Finalizer" daemon prio=8 tid=0x02c70000 nid=0x708 in object.wait () [0x050cf000]

Java.lang.Thread.State:WAITING (on object monitor)

At java.lang.Object.wait (Native Method)

-Waiting on <0x25200fc8> (a java.lang.ref.referencequeue$lock)

At Java.lang.ref.ReferenceQueue.remove (referencequeue.java:135)

-Locked <0x25200fc8> (a java.lang.ref.referencequeue$lock)

At Java.lang.ref.ReferenceQueue.remove (referencequeue.java:151)

At Java.lang.ref.finalizer$finalizerthread.run (finalizer.java:209)

"Reference Handler" daemon prio=10 tid=0x02c6e800 Nid=0xf40 in object.wait () [0x0503f000]

Java.lang.Thread.State:WAITING (on object monitor)

At java.lang.Object.wait (Native Method)

-Waiting on <0x25200db0> (a java.lang.ref.reference$lock)

At Java.lang.Object.wait (object.java:503)

At Java.lang.ref.reference$referencehandler.run (reference.java:133)

-Locked <0x25200db0> (a java.lang.ref.reference$lock)

"VM Thread" prio=10 tid=0x02c6d400 nid=0x1150 runnable

"VM periodic Task Thread" prio=10 tid=0x02d16400 nid=0x3130 waiting on condition

JNI Global references:111

Found One java-level deadlock:

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

"Thread-1":

Waiting to lock monitor 0x02c73be4 (Object 0x252811c0, a java.lang.Object),

Which is held by "Thread-0"

"Thread-0":

Waiting to lock monitor 0x02c75704 (Object 0x252811c8, a java.lang.Object),

Which is held by "Thread-1"

Java stack information for the threads listed above:

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

"Thread-1":

At Threadb.run (deadlock.java:64)

-Waiting to lock <0x252811c0> (a java.lang.Object)

-Locked <0x252811c8> (a java.lang.Object)

"Thread-0":

At Threada.run (deadlock.java:37)

-Waiting to lock <0x252811c8> (a java.lang.Object)

-Locked <0x252811c0> (a java.lang.Object)

Found 1 deadlock.

Heap

def New Generation Total 4928K, used 867K [0x25200000, 0x25750000, 0x2a750000)

Eden Space 4416K, 19% used [0x25200000, 0X252D8FE0, 0x25650000)

From space 512K, 0% used [0x25650000, 0x25650000, 0x256d0000)

To space 512K, 0% used [0x256d0000, 0x256d0000, 0x25750000)

Tenured generation total 10944K, used 0K [0x2a750000, 0x2b200000, 0x35200000)

The space 10944K, 0% used [0x2a750000, 0x2a750000, 0x2a750200, 0x2b200000)

Compacting Perm Gen Total 12288K, used 157K [0x35200000, 0x35e00000, 0x39200000)

The space 12288K, 1% used [0x35200000, 0x35227730, 0x35227800, 0x35e00000)

Ro space 10240K, 44% used [0x39200000, 0x3967a688, 0x3967a800, 0x39c00000)

RW Space 12288K, 52% used [0x39c00000, 0x3a254170, 0x3a254200, 0x3a800000)

2018-07-22 period Java deadlock small case programming