jvm jstack的使用

有些时候我们需要查看下jvm中的线程执行情况，比如，发现服务器的CPU的负载突然增 高了、出现了死锁、死循环等，我们该如何分析呢？

由于程序是正常运行的，没有任何的输出，从日志方面也看不出什么问题，所以就需要 看下jvm的内部线程的执行情况，然后再进行分析查找出原因。
这个时候，就需要借助于jstack命令了，jstack的作用是将正在运行的jvm的线程情况进 行快照，并且打印出来

jstack用法

#用法：jstack <pid>
[root@node01 bin]# jstack 2203
Full thread dump Java HotSpot(TM) 64‐Bit Server VM (25.141‐b15 mixed
mode):
"Attach Listener" #24 daemon prio=9 os_prio=0 tid=0x00007fabb4001000
nid=0x906 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"http‐bio‐8080‐exec‐5" #23 daemon prio=5 os_prio=0 tid=0x00007fabb057c000
nid=0x8e1 waiting on condition [0x00007fabd05b8000]
java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
‐ parking to wait for <0x00000000f8508360> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awa
it(AbstractQueuedSynchronizer.java:2039)
    
at
java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:44
2)
    
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
at
java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1
074)
    
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java
:1134)
    
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.jav
a:624)
    
at
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread
.java:61)
    
    at java.lang.Thread.run(Thread.java:748)
"http‐bio‐8080‐exec‐4" #22 daemon prio=5 os_prio=0 tid=0x00007fab9c113800
nid=0x8e0 waiting on condition [0x00007fabd06b9000]
java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
‐ parking to wait for <0x00000000f8508360> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awa
it(AbstractQueuedSynchronizer.java:2039)
    
at
java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:44
2)
    
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
    at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
at
java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1
074)
    
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java
:1134)
    
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.jav
a:624)
    
at
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread
.java:61)
    
    at java.lang.Thread.run(Thread.java:748)
"http‐bio‐8080‐exec‐3" #21 daemon prio=5 os_prio=0 tid=0x0000000001aeb800
nid=0x8df waiting on condition [0x00007fabd09ba000]
java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
‐ parking to wait for <0x00000000f8508360> (a
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awa
it(AbstractQueuedSynchronizer.java:2039)
    
    at