如何检测死锁
package threadStudy.deadLock;
/**
* @description:
* @author: brave.chen
* @create: 2020-03-07 11:22
**/
public class NormalDeadLock {
private static Object first = new Object();
private static Object second = new Object();
private static void findToSecond() throws InterruptedException{
String str = Thread.currentThread().getName();
synchronized (first){
System.out.println("threadName = "+str + " get first");
Thread.sleep(100);
synchronized (second){
System.out.println("threadName = "+str +" get second");
}
}
}
private static void secondToFirst() throws InterruptedException{
String str = Thread.currentThread().getName();
synchronized (second){
System.out.println("threadName = "+str + " get second");
Thread.sleep(100);
synchronized (first){
System.out.println("threadName = "+str +" get first");
}
}
}
public static void main(String[] args) {
Thread t1 = new Thread(() -> {
try {
findToSecond();
} catch (InterruptedException e) {
e.printStackTrace();
}
});
Thread t2 = new Thread(() -> {
try {
secondToFirst();
} catch (InterruptedException e) {
e.printStackTrace();
}
});
t1.start();
t2.start();
}
}
chenweideMacBook-Pro:study-2019 chenwei$ jps
49680 NormalDeadLock
49681 Launcher
1080 QuorumPeerMain
56987 Jps
6126
chenweideMacBook-Pro:study-2019 chenwei$ jstack 49680
2020-03-07 11:29:35
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.201-b09 mixed mode):
"Attach Listener" #13 daemon prio=9 os_prio=31 tid=0x00007fcd21868000 nid=0x2f0b waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"DestroyJavaVM" #12 prio=5 os_prio=31 tid=0x00007fcd22803000 nid=0x2603 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Thread-1" #11 prio=5 os_prio=31 tid=0x00007fcd228b6800 nid=0x3d03 waiting for monitor entry [0x000070000c9a2000]
java.lang.Thread.State: BLOCKED (on object monitor)
at threadStudy.deadLock.NormalDeadLock.secondToFirst(NormalDeadLock.java:29)
- waiting to lock <0x00000007956a9818> (a java.lang.Object)
- locked <0x00000007956a9828> (a java.lang.Object)
at threadStudy.deadLock.NormalDeadLock.lambda$main$1(NormalDeadLock.java:44)
at threadStudy.deadLock.NormalDeadLock$$Lambda$2/2065951873.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
"Thread-0" #10 prio=5 os_prio=31 tid=0x00007fcd2313a000 nid=0x3c03 waiting for monitor entry [0x000070000c89f000]
java.lang.Thread.State: BLOCKED (on object monitor)
at threadStudy.deadLock.NormalDeadLock.findToSecond(NormalDeadLock.java:18)
- waiting to lock <0x00000007956a9828> (a java.lang.Object)
- locked <0x00000007956a9818> (a java.lang.Object)
at threadStudy.deadLock.NormalDeadLock.lambda$main$0(NormalDeadLock.java:37)
at threadStudy.deadLock.NormalDeadLock$$Lambda$1/668386784.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
"Service Thread" #9 daemon prio=9 os_prio=31 tid=0x00007fcd22897000 nid=0x3a03 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C1 CompilerThread2" #8 daemon prio=9 os_prio=31 tid=0x00007fcd21839800 nid=0x4703 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" #7 daemon prio=9 os_prio=31 tid=0x00007fcd22020000 nid=0x3803 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" #6 daemon prio=9 os_prio=31 tid=0x00007fcd22841800 nid=0x4903 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Monitor Ctrl-Break" #5 daemon prio=5 os_prio=31 tid=0x00007fcd23065000 nid=0x3703 runnable [0x000070000c28d000]
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 <0x00000007957095a0> (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 <0x00000007957095a0> (a java.io.InputStreamReader)
at java.io.BufferedReader.readLine(BufferedReader.java:389)
at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)
"Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007fcd22815000 nid=0x3503 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007fcd23006000 nid=0x4e03 in Object.wait() [0x000070000c087000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x0000000795588ed0> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
- locked <0x0000000795588ed0> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)
"Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007fcd21831000 nid=0x2b03 in Object.wait() [0x000070000bf84000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x0000000795586bf8> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:502)
at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
- locked <0x0000000795586bf8> (a java.lang.ref.Reference$Lock)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)
"VM Thread" os_prio=31 tid=0x00007fcd23005000 nid=0x5003 runnable
"GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007fcd2200a800 nid=0x1d07 runnable
"GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007fcd2200b000 nid=0x1e03 runnable
"GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007fcd21808800 nid=0x5403 runnable
"GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007fcd2280b800 nid=0x5203 runnable
"VM Periodic Task Thread" os_prio=31 tid=0x00007fcd22077800 nid=0x4403 waiting on condition
JNI global references: 320
Found one Java-level deadlock:
=============================
"Thread-1":
waiting to lock monitor 0x00007fcd21834368 (object 0x00000007956a9818, a java.lang.Object),
which is held by "Thread-0"
"Thread-0":
waiting to lock monitor 0x00007fcd21836d58 (object 0x00000007956a9828, a java.lang.Object),
which is held by "Thread-1"
Java stack information for the threads listed above:
===================================================
"Thread-1":
at threadStudy.deadLock.NormalDeadLock.secondToFirst(NormalDeadLock.java:29)
- waiting to lock <0x00000007956a9818> (a java.lang.Object)
- locked <0x00000007956a9828> (a java.lang.Object)
at threadStudy.deadLock.NormalDeadLock.lambda$main$1(NormalDeadLock.java:44)
at threadStudy.deadLock.NormalDeadLock$$Lambda$2/2065951873.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
"Thread-0":
at threadStudy.deadLock.NormalDeadLock.findToSecond(NormalDeadLock.java:18)
- waiting to lock <0x00000007956a9828> (a java.lang.Object)
- locked <0x00000007956a9818> (a java.lang.Object)
at threadStudy.deadLock.NormalDeadLock.lambda$main$0(NormalDeadLock.java:37)
at threadStudy.deadLock.NormalDeadLock$$Lambda$1/668386784.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
Found 1 deadlock.
死锁预防
让线程获取锁的顺序一致
死锁检测
jps 查看java 进程信息 jstack +进程号 知道哪个死锁