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
