java 线程状态——情况续说

最新推荐文章于 2022-08-09 20:44:20 发布

sam-fat-chang

最新推荐文章于 2022-08-09 20:44:20 发布

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分类专栏： java concurrency 文章标签： java 线程状态 java线程状态 io waiting

本文链接：https://blog.youkuaiyun.com/u014783753/article/details/55101571

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本文通过具体示例探讨了Java中线程状态的变化过程，特别是从RUNNING到WAITING/TIMED_WAITING的转变，并详细分析了使用ArrayBlockingQueue导致线程阻塞的具体表现。

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参考链接：

java 线程状态

situation1/2使得线程状态从RUNNING转化为WAITING/TIMED_WAITING

还有一种情况就是IO阻塞，例子如下：

import java.util.concurrent.ArrayBlockingQueue;

public class c
{
        private static ArrayBlockingQueue<String> blockingQueue = new ArrayBlockingQueue<String>(1);
        public static void main(String[] args)
        {
                blockingQueue.add("Str1");
                try
                {
                        blockingQueue.put("Str2");
                }catch(Exception e)
                {
                        e.printStackTrace();
                }
        }
}
~

jstack输出如下：

2017-02-14 10:10:48
Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.80-b11 mixed mode):

   java.lang.Thread.State: RUNNABLE

   java.lang.Thread.State: RUNNABLE

   java.lang.Thread.State: RUNNABLE

   java.lang.Thread.State: RUNNABLE

   java.lang.Thread.State: RUNNABLE

   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000007d7004858> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
        - locked <0x00000007d7004858> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)

   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000007d7004470> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:503)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
        - locked <0x00000007d7004470> (a java.lang.ref.Reference$Lock)

"main" prio=10 tid=0x00007f4038008800 nid=0x30e6 waiting on condition [0x00007f403ccc7000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000007d704a740> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
        at java.util.concurrent.ArrayBlockingQueue.put(ArrayBlockingQueue.java:324)
        at c.main(c.java:12)

"VM Thread" prio=10 tid=0x00007f4038071000 nid=0x30ef runnable

"GC task thread#0 (ParallelGC)" prio=10 tid=0x00007f403801e000 nid=0x30e7 runnable

"GC task thread#1 (ParallelGC)" prio=10 tid=0x00007f4038020000 nid=0x30e8 runnable

"GC task thread#2 (ParallelGC)" prio=10 tid=0x00007f4038022000 nid=0x30e9 runnable

从以上输出我们要注意

WAITING(parking)

这段字符串说明了目前线程的状态

还需要注意：

- parking to wait for <0x00000007d704a740> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)

说明了线程WAITING的地方