java故障诊断案例分析: 死锁瓶颈(性能分析)
只要是java程序, 都可以使用这种方式来分析性能的瓶颈
1. Dump信息查看
Thread dump信息对于性能诊断非常有用
kill 命令使用
kill : 杀死一个进程
-9: 强制杀死一个进程
-3: 打印进程的Thread dump信息
linux系统: kill -3 pid
windows: 在命令行窗口上, 按一个组合键: ctrl + break(fn+B键)
2. 死锁程序分析
java的一个死锁程序代码:
public class DeadLock {
final Object lockA = new Object();
final Object lockB = new Object();
public static void main(String[] args) {
DeadLock demo = new DeadLock();
demo.startLock();
}
private 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: ***: Lock A");
try {
sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (lockB) {
System.out.println("*** Thread B: ***: Lock 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: ***: Lock B");
try {
sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (lockA) {
System.out.println("*** Thread A: ***: Lock A");
}
}
System.out.println("*** Thread B: ***: Finished");
}
}
- 执行程序, 结果如下:
*** Thread A: ***: Lock A
*** Thread B: ***: Lock B- 执行如下shell命令:
192:javatest lingjing$ jps
32246 Launcher
32247 DeadLock
32055
32248 Jps
192:javatest lingjing$ kill -3 32247
- 在原来程序的终端变成如下结果:
*** Thread A: ***: Lock A
*** Thread B: ***: Lock B
2019-05-26 11:01:24
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.151-b12 mixed mode):
"DestroyJavaVM" #13 prio=5 os_prio=31 tid=0x00007fe4fa012000 nid=0x2603 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Thread-1" #12 prio=5 os_prio=31 tid=0x00007fe4fc82a000 nid=0xa603 waiting for monitor entry [0x00007000050a8000]
java.lang.Thread.State: BLOCKED (on object monitor)
at javatest.ThreadB.run(DeadLock.java:78)
- waiting to lock <0x000000076ac6ca00> (a java.lang.Object)
- locked <0x000000076ac6ca10> (a java.lang.Object)
"Thread-0" #11 prio=5 os_prio=31 tid=0x00007fe4fc801000 nid=0xa803 waiting for monitor entry [0x0000700004fa5000]
java.lang.Thread.State: BLOCKED (on object monitor)
at javatest.ThreadA.run(DeadLock.java:50)
- waiting to lock <0x000000076ac6ca10> (a java.lang.Object)
- locked <0x000000076ac6ca00> (a java.lang.Object)
"Service Thread" #10 daemon prio=9 os_prio=31 tid=0x00007fe4fd0d0000 nid=0x4103 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C1 CompilerThread3" #9 daemon prio=9 os_prio=31 tid=0x00007fe4fd0d3000 nid=0x4303 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread2" #8 daemon prio=9 os_prio=31 tid=0x00007fe4fd0d2000 nid=0x3f03 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" #7 daemon prio=9 os_prio=31 tid=0x00007fe4fd0d1800 nid=0x3e03 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" #6 daemon prio=9 os_prio=31 tid=0x00007fe4fd0d0800 nid=0x4703 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Monitor Ctrl-Break" #5 daemon prio=5 os_prio=31 tid=0x00007fe4fd0ce000 nid=0x4903 runnable [0x0000700004890000]
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:171)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
- locked <0x000000076adcaf90> (a java.io.InputStreamReader)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at java.io.BufferedReader.fill(BufferedReader.java:161)
at java.io.BufferedReader.readLine(BufferedReader.java:324)
- locked <0x000000076adcaf90> (a java.io.InputStreamReader)
at java.io.BufferedReader.readLine(BufferedReader.java:389)
at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)
"Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007fe4fa003800 nid=0x3d03 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007fe4f985b800 nid=0x3603 in Object.wait() [0x000070000468a000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x000000076ab08ec8> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
- locked <0x000000076ab08ec8> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)
"Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007fe4fc815800 nid=0x3403 in Object.wait() [0x0000700004587000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x000000076ab06b68> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:502)
at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
- locked <0x000000076ab06b68> (a java.lang.ref.Reference$Lock)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)
"VM Thread" os_prio=31 tid=0x00007fe4f985b000 nid=0x3203 runnable
"GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007fe4f9800800 nid=0x1f07 runnable
"GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007fe4fc80a800 nid=0x2a03 runnable
"GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007fe4fc001000 nid=0x2c03 runnable
"GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007fe4fc80b000 nid=0x5303 runnable
"GC task thread#4 (ParallelGC)" os_prio=31 tid=0x00007fe4fc80b800 nid=0x5203 runnable
"GC task thread#5 (ParallelGC)" os_prio=31 tid=0x00007fe4fc80c000 nid=0x5003 runnable
"GC task thread#6 (ParallelGC)" os_prio=31 tid=0x00007fe4fc80d000 nid=0x4f03 runnable
"GC task thread#7 (ParallelGC)" os_prio=31 tid=0x00007fe4f9813000 nid=0x3003 runnable
"VM Periodic Task Thread" os_prio=31 tid=0x00007fe4fd0d3800 nid=0x5503 waiting on condition
JNI global references: 22
Found one Java-level deadlock:
=============================
"Thread-1":
waiting to lock monitor 0x00007fe4fd005568 (object 0x000000076ac6ca00, a java.lang.Object),
which is held by "Thread-0"
"Thread-0":
waiting to lock monitor 0x00007fe4fd007d48 (object 0x000000076ac6ca10, a java.lang.Object),
which is held by "Thread-1"
Java stack information for the threads listed above:
===================================================
"Thread-1":
at javatest.ThreadB.run(DeadLock.java:78)
- waiting to lock <0x000000076ac6ca00> (a java.lang.Object)
- locked <0x000000076ac6ca10> (a java.lang.Object)
"Thread-0":
at javatest.ThreadA.run(DeadLock.java:50)
- waiting to lock <0x000000076ac6ca10> (a java.lang.Object)
- locked <0x000000076ac6ca00> (a java.lang.Object)
Found 1 deadlock.
Heap
PSYoungGen total 76288K, used 10486K [0x000000076ab00000, 0x0000000770000000, 0x00000007c0000000)
eden space 65536K, 16% used [0x000000076ab00000,0x000000076b53d968,0x000000076eb00000)
from space 10752K, 0% used [0x000000076f580000,0x000000076f580000,0x0000000770000000)
to space 10752K, 0% used [0x000000076eb00000,0x000000076eb00000,0x000000076f580000)
ParOldGen total 175104K, used 0K [0x00000006c0000000, 0x00000006cab00000, 0x000000076ab00000)
object space 175104K, 0% used [0x00000006c0000000,0x00000006c0000000,0x00000006cab00000)
Metaspace used 3297K, capacity 4500K, committed 4864K, reserved 1056768K
class space used 364K, capacity 388K, committed 512K, reserved 1048576K
在上面的程序中, 如下的一段, 我们可以发现一个死锁, 并给出一个提示, 并提示我们在代码的78行和50行有错误, 所以我们分析代码逻辑, 来帮助我们找到死锁的节点
Java stack information for the threads listed above:
===================================================
"Thread-1":
at javatest.ThreadB.run(DeadLock.java:78)
- waiting to lock <0x000000076ac6ca00> (a java.lang.Object)
- locked <0x000000076ac6ca10> (a java.lang.Object)
"Thread-0":
at javatest.ThreadA.run(DeadLock.java:50)
- waiting to lock <0x000000076ac6ca10> (a java.lang.Object)
- locked <0x000000076ac6ca00> (a java.lang.Object)
Found 1 deadlock.