Thread相關學習之二 - JavaThread&JVMTIThread的生命週期

執行緒生命週期

JavaThread生命週期

執行緒生命週期就在上述的6個狀態中流轉，如下圖：

Snip20180703_22.png

JVMTIThreadState定義

不過在jvmti.xml中，看到了jvmti(JVM Tool Interface)定義的相關ThreadState，看下：

<constants id="jvmtiThreadState" label="Thread State Flags" kind="bits">
      <constant id="JVMTI_THREAD_STATE_ALIVE" num="0x0001">
        Thread is alive. Zero if thread is new (not started) or terminated.
      </constant>
      <constant id="JVMTI_THREAD_STATE_TERMINATED" num="0x0002">
        Thread has completed execution.
      </constant>
      <constant id="JVMTI_THREAD_STATE_RUNNABLE" num="0x0004">
        Thread is runnable.
      </constant>
      <constant id="JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER" num="0x0400">
        Thread is waiting to enter a synchronization block/method or,
            after an <code>Object.wait()</code>, waiting to re-enter a 
            synchronization block/method.
      </constant>
      <constant id="JVMTI_THREAD_STATE_WAITING" num="0x0080">
        Thread is waiting.
      </constant>
      <constant id="JVMTI_THREAD_STATE_WAITING_INDEFINITELY" num="0x0010">
        Thread is waiting without a timeout.
            For example, <code>Object.wait()</code>.
      </constant>
      <constant id="JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT" num="0x0020">
        Thread is waiting with a maximum time to wait specified.
            For example, <code>Object.wait(long)</code>.
      </constant>
      <constant id="JVMTI_THREAD_STATE_SLEEPING" num="0x0040">
        Thread is sleeping -- <code>Thread.sleep(long)</code>.
      </constant>
      <constant id="JVMTI_THREAD_STATE_IN_OBJECT_WAIT" num="0x0100">
        Thread is waiting on an object monitor -- <code>Object.wait</code>.
      </constant>
      <constant id="JVMTI_THREAD_STATE_PARKED" num="0x0200">
        Thread is parked, for example: <code>LockSupport.park</code>,
            <code>LockSupport.parkUtil</code> and <code>LockSupport.parkNanos</code>.
      </constant>
      <constant id="JVMTI_THREAD_STATE_SUSPENDED" num="0x100000">
        Thread suspended.
        <code>java.lang.Thread.suspend()</code>
        or a <jvmti/> suspend function 
            (such as <functionlink id="SuspendThread"></functionlink>) 
            has been called on the thread. If this bit
        is set, the other bits refer to the thread state before suspension.
      </constant>
      <constant id="JVMTI_THREAD_STATE_INTERRUPTED" num="0x200000">
        Thread has been interrupted.
      </constant>
      <constant id="JVMTI_THREAD_STATE_IN_NATIVE" num="0x400000">
            Thread is in native code--that is, a native method is running
            which has not called back into the VM or Java programming
            language code.
            <p/>
            This flag is not set when running VM compiled Java programming
            language code nor is it set when running VM code or
            VM support code. Native VM interface functions, such as JNI and
            <jvmti/> functions, may be implemented as VM code.
      </constant>
      <constant id="JVMTI_THREAD_STATE_VENDOR_1" num="0x10000000">
            Defined by VM vendor.
      </constant>
      <constant id="JVMTI_THREAD_STATE_VENDOR_2" num="0x20000000">
            Defined by VM vendor.
      </constant>
      <constant id="JVMTI_THREAD_STATE_VENDOR_3" num="0x40000000">
            Defined by VM vendor.
      </constant>
    </constants>

可以看到，這裡使用十六進位制表示一個具體的ThreadState值。整理一下：

注意其中的值都是16進位制資料，而實際上是用位（bit）來組合計算的。