你将如何使用 thread dump？你将如何分析 Thread dump？

新建状态（New）

用 new 语句创建的线程处于新建状态，此时它和其他 Java 对象一样，仅仅在堆区

中被分配了内存。

就绪状态（Runnable）

当一个线程对象创建后，其他线程调用它的 start()方法，该线程就进入就绪状态，

Java 虚拟机会为它创建方法调用栈和程序计数器。处于这个状态的线程位于可运

行池中，等待获得 CPU 的使用权。

运行状态（Running）

处于这个状态的线程占用 CPU，执行程序代码。只有处于就绪状态的线程才有机

会转到运行状态。

阻塞状态（Blocked）

阻塞状态是指线程因为某些原因放弃 CPU，暂时停止运行。当线程处于阻塞状态

时，Java 虚拟机不会给线程分配 CPU。直到线程重新进入就绪状态，它才有机会

转到运行状态。

阻塞状态可分为以下 3 种：

位于对象等待池中的阻塞状态（Blocked in object’s wait pool）：

当线程处于运行状态时，如果执行了某个对象的 wait()方法，Java 虚拟机就会把

线程放到这个对象的等待池中，这涉及到“线程通信”的内容。

位于对象锁池中的阻塞状态（Blocked in object’s lock pool）：

当线程处于运行状态时，试图获得某个对象的同步锁时，如果该对象的同步锁已

经被其他线程占用，Java 虚拟机就会把这个线程放到这个对象的锁池中，这涉及

到“线程同步”的内容。

其他阻塞状态（Otherwise Blocked）：

当前线程执行了 sleep()方法，或者调用了其他线程的 join()方法，或者发出了 I/O

请求时，就会进入这个状态。

死亡状态（Dead）

当线程退出 run()方法时，就进入死亡状态，该线程结束生命周期。

我们运行之前的那个死锁代码 SimpleDeadLock.java，然后尝试输出信息(

/* 时间，jvm 信息 */

2017-11-01 17:36:28

Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.144-b01 mixed

mode):

/* 线程名称：DestroyJavaVM

编号：#13

优先级：5

系统优先级：0

jvm 内部线程 id：0x0000000001c88800

对应系统线程 id（NativeThread ID）：0x1c18

线程状态： waiting on condition [0x0000000000000000] （等待某个条件）

线程详细状态：java.lang.Thread.State: RUNNABLE 及之后所有*/

"DestroyJavaVM" #13 prio=5 os_prio=0 tid=0x0000000001c88800

nid=0x1c18 waiting on condition [0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"Thread-1" #12 prio=5 os_prio=0 tid=0x0000000018d49000

nid=0x17b8 waiting for monitor entry [0x0000000019d7f000]

/* 线程状态：阻塞（在对象同步上）

代码位置：at

com.leo.interview.SimpleDeadLock$B.run(SimpleDeadLock.java:56)

等待锁：0x00000000d629b4d8

已经获得锁：0x00000000d629b4e8*/

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

at

com.leo.interview.SimpleDeadLock$B.run(SimpleDeadLock.java:56)

- waiting to lock <0x00000000d629b4d8> (a java.lang.Object)

- locked <0x00000000d629b4e8> (a java.lang.Object)

"Thread-0" #11 prio=5 os_prio=0 tid=0x0000000018d44000 nid=0x1ebc

waiting for monitor entry [0x000000001907f000]

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

at

com.leo.interview.SimpleDeadLock$A.run(SimpleDeadLock.java:34)

- waiting to lock <0x00000000d629b4e8> (a java.lang.Object)

- locked <0x00000000d629b4d8> (a java.lang.Object)

"Service Thread" #10 daemon prio=9 os_prio=0

tid=0x0000000018ca5000 nid=0x1264 runnable [0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"C1 CompilerThread2" #9 daemon prio=9 os_prio=2

tid=0x0000000018c46000 nid=0xb8c waiting on condition

[0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #8 daemon prio=9 os_prio=2

tid=0x0000000018be4800 nid=0x1db4 waiting on condition

[0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #7 daemon prio=9 os_prio=2

tid=0x0000000018be3800 nid=0x810 waiting on condition

[0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"Monitor Ctrl-Break" #6 daemon prio=5 os_prio=0

tid=0x0000000018bcc800 nid=0x1c24 runnable [0x00000000193ce000]

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 <0x00000000d632b928> (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 <0x00000000d632b928> (a java.io.InputStreamReader)

at java.io.BufferedReader.readLine(BufferedReader.java:389)

at

com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:6

4)

"Attach Listener" #5 daemon prio=5 os_prio=2

tid=0x0000000017781800 nid=0x524 runnable [0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2

tid=0x000000001778f800 nid=0x1b08 waiting on condition

[0x0000000000000000]

java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x000000001776a800

nid=0xdac in Object.wait() [0x0000000018b6f000]

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

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

- waiting on <0x00000000d6108ec8> (a

java.lang.ref.ReferenceQueue$Lock)

at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)

- locked <0x00000000d6108ec8> (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=2

tid=0x0000000017723800 nid=0x1670 in Object.wait()

[0x00000000189ef000]

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

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

- waiting on <0x00000000d6106b68> (a

java.lang.ref.Reference$Lock)

at java.lang.Object.wait(Object.java:502)

at java.lang.ref.Reference.tryHandlePending(Reference.java:191)

- locked <0x00000000d6106b68> (a java.lang.ref.Reference$Lock)

at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=2 tid=0x000000001771b800 nid=0x604 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x0000000001c9d800

nid=0x9f0 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x0000000001c9f000

nid=0x154c runnable

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x0000000001ca0800

nid=0xcd0 runnable

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x0000000001ca2000

nid=0x1e58 runnable

"VM Periodic Task Thread" os_prio=2 tid=0x0000000018c5a000

nid=0x1b58 waiting on condition

JNI global references: 33

/* 此处可以看待死锁的相关信息！ */

Found one Java-level deadlock:

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

"Thread-1":

waiting to lock monitor 0x0000000017729fc8 (object

0x00000000d629b4d8, a java.lang.Object),

which is held by "Thread-0"

"Thread-0":

waiting to lock monitor 0x0000000017727738 (object

0x00000000d629b4e8, a java.lang.Object),

which is held by "Thread-1"

Java stack information for the threads listed above:

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

=====

"Thread-1":

at

com.leo.interview.SimpleDeadLock$B.run(SimpleDeadLock.java:56)

- waiting to lock <0x00000000d629b4d8> (a java.lang.Object)

- locked <0x00000000d629b4e8> (a java.lang.Object)

"Thread-0":

at

com.leo.interview.SimpleDeadLock$A.run(SimpleDeadLock.java:34)

- waiting to lock <0x00000000d629b4e8> (a java.lang.Object)

- locked <0x00000000d629b4d8> (a java.lang.Object)

Found 1 deadlock.

/* 内存使用状况，详情得看 JVM 方面的书 */

Heap

PSYoungGen

total 37888K, used 4590K [0x00000000d6100000,

0x00000000d8b00000, 0x0000000100000000)

eden space 32768K, 14% used

[0x00000000d6100000,0x00000000d657b968,0x00000000d8100000)

from space 5120K, 0% used

[0x00000000d8600000,0x00000000d8600000,0x00000000d8b00000)

to

space 5120K, 0% used

[0x00000000d8100000,0x00000000d8100000,0x00000000d8600000)

ParOldGen

total 86016K, used 0K [0x0000000082200000,

0x0000000087600000, 0x00000000d6100000)

object space 86016K, 0% used

[0x0000000082200000,0x0000000082200000,0x0000000087600000)

Metaspace

used 3474K, capacity 4500K, committed 4864K,

reserved 1056768K

class space

used 382K, capacity 388K, committed 512K, reserved

1048576K