创建名为“ {java}”的线程（即轻量级进程）是为了什么？

创建名为“ {java}”的线程（即轻量级进程）是为了什么？

所有这些线程都属于JVM。
运行

jstack <pid>

以获取线程列表。

"main" #1 prio=5 os_prio=0 cpu=150.00ms elapsed=8.04s tid=0x00007f9f90011000 nid=0x107 waiting on condition  [0x00007f9f99f9f000]   java.lang.Thread.State: TIMED_WAITING (sleeping)        at java.lang.Thread.sleep(java.base@11.0.1/Native Method)        at java.lang.Thread.sleep(java.base@11.0.1/Thread.java:339)        at java.util.concurrent.TimeUnit.sleep(java.base@11.0.1/TimeUnit.java:446)        at com.mycompany.app.Main.main(Main.java:10)"Reference Handler" #2 daemon prio=10 os_prio=0 cpu=0.00ms elapsed=7.95s tid=0x00007f9f901f9000 nid=0x10e waiting on condition  [0x00007f9f6c10f000]   java.lang.Thread.State: RUNNABLE        at java.lang.ref.Reference.waitForReferencePendingList(java.base@11.0.1/Native Method)        at java.lang.ref.Reference.processPendingReferences(java.base@11.0.1/Reference.java:241)        at java.lang.ref.Reference$ReferenceHandler.run(java.base@11.0.1/Reference.java:213)"Finalizer" #3 daemon prio=8 os_prio=0 cpu=0.00ms elapsed=7.95s tid=0x00007f9f901fd800 nid=0x10f in Object.wait()  [0x00007f9f65fef000]   java.lang.Thread.State: WAITING (on object monitor)        at java.lang.Object.wait(java.base@11.0.1/Native Method)        - waiting on <0x0000000712108f80> (a java.lang.ref.ReferenceQueue$Lock)        at java.lang.ref.ReferenceQueue.remove(java.base@11.0.1/ReferenceQueue.java:155)        - waiting to re-lock in wait() <0x0000000712108f80> (a java.lang.ref.ReferenceQueue$Lock)        at java.lang.ref.ReferenceQueue.remove(java.base@11.0.1/ReferenceQueue.java:176)        at java.lang.ref.Finalizer$FinalizerThread.run(java.base@11.0.1/Finalizer.java:170)"Signal Dispatcher" #4 daemon prio=9 os_prio=0 cpu=0.00ms elapsed=7.93s tid=0x00007f9f90210000 nid=0x110 runnable  [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 cpu=40.00ms elapsed=7.93s tid=0x00007f9f90212000 nid=0x111 waiting on condition  [0x0000000000000000]   java.lang.Thread.State: RUNNABLE   No compile task"C1 CompilerThread0" #7 daemon prio=9 os_prio=0 cpu=40.00ms elapsed=7.93s tid=0x00007f9f90214000 nid=0x112 waiting on condition  [0x0000000000000000]   java.lang.Thread.State: RUNNABLE   No compile task"Sweeper thread" #8 daemon prio=9 os_prio=0 cpu=10.00ms elapsed=7.93s tid=0x00007f9f90216000 nid=0x113 runnable  [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"Service Thread" #9 daemon prio=9 os_prio=0 cpu=0.00ms elapsed=7.90s tid=0x00007f9f902d3800 nid=0x114 runnable  [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"Common-Cleaner" #10 daemon prio=8 os_prio=0 cpu=0.00ms elapsed=7.89s tid=0x00007f9f902df800 nid=0x116 in Object.wait()  [0x00007f9f656ef000]   java.lang.Thread.State: TIMED_WAITING (on object monitor)        at java.lang.Object.wait(java.base@11.0.1/Native Method)        - waiting on <0x0000000712002df0> (a java.lang.ref.ReferenceQueue$Lock)        at java.lang.ref.ReferenceQueue.remove(java.base@11.0.1/ReferenceQueue.java:155)        - waiting to re-lock in wait() <0x0000000712002df0> (a java.lang.ref.ReferenceQueue$Lock)        at jdk.internal.ref.CleanerImpl.run(java.base@11.0.1/CleanerImpl.java:148)        at java.lang.Thread.run(java.base@11.0.1/Thread.java:834)        at jdk.internal.misc.InnocuousThread.run(java.base@11.0.1/InnocuousThread.java:134)"Attach Listener" #11 daemon prio=9 os_prio=0 cpu=0.00ms elapsed=0.21s tid=0x00007f9f44001000 nid=0x126 waiting on condition  [0x0000000000000000]   java.lang.Thread.State: RUNNABLE"VM Thread" os_prio=0 cpu=0.00ms elapsed=7.95s tid=0x00007f9f901f1000 nid=0x10d runnable"GC Thread#0" os_prio=0 cpu=0.00ms elapsed=8.01s tid=0x00007f9f90038800 nid=0x108 runnable"G1 Main Marker" os_prio=0 cpu=0.00ms elapsed=8.00s tid=0x00007f9f90097800 nid=0x109 runnable"G1 Conc#0" os_prio=0 cpu=0.00ms elapsed=8.00s tid=0x00007f9f90099800 nid=0x10a runnable"G1 Refine#0" os_prio=0 cpu=0.00ms elapsed=8.00s tid=0x00007f9f9018d000 nid=0x10b runnable"G1 Young RemSet Sampling" os_prio=0 cpu=0.00ms elapsed=8.00s tid=0x00007f9f9018f000 nid=0x10c runnable"VM Periodic Task Thread" os_prio=0 cpu=0.00ms elapsed=7.90s tid=0x00007f9f902d6000 nid=0x115 waiting on condition

这nid是 *** 作系统中线程的十六进制ID，您可以将其与的输出匹配pstree。

第一个命名main的线程是执行代码的线程。

• Reference Handler

  线程负责将垃圾收集器发现的弱引用，软引用和幻像引用添加到其注册的ReferenceQueues中。

• Finalizerfinalize

  准备运行的对象的线程运行方法。

• Signal Dispatcher

  等待特定的 *** 作系统信号并处理它们。特别是，它使线程转储上SIGQUIT，还启动对VM关机过程SIGTERM，SIGINT和SIGHUP。

CompilerThreads

执行字节码的JIT编译。

• Sweeper thread

  清理过时的编译方法。

• Service Thread

  运行一些后台JVM任务：检测内存不足情况，清理StringTable和SymbolTable，发送延迟的JVMTI事件和GC通知等。

• Common-Cleaner

  运行java.lang.ref.Cleaner实例的清理 *** 作。

• Attach Listener

  线程支持动态附加机制。它侦听传入的动态附加连接并执行VM命令。例如，它是由使用jstack，jmap与jcmd实用程序。

• VM Thread

  运行需要一个内部VM *** 作还原点。这样的 *** 作的示例是反优化，类重新定义，有偏的锁吊销，线程转储，堆检查等。

• G1

  线程参与垃圾回收。

• VM Periodic Task Thread

  用于模拟定时器中断。