What is the life cycle of a thread?

The life cycle of a thread, that is, the thread state has 5 stages: New state (New), Ready state (Runnable), Running state (Running), Blocked state (Blocked), and Death state (Dead).

When a thread is created and started, it will not enter the execution state as soon as it starts, nor will it always be in the execution state, but will go through 5 states. . This article will give you the life cycle of threads and let you understand the five states of threads. [Related video tutorial recommendations: Java Tutorial]

New state (New)

When the program uses the new keyword After a thread is created, the thread is in the newly created state. Example:

Thread t = new MyThread();

Ready state (Runnable)

After calling the start() method, the thread It will be in the ready state; at this time, it can only mean that this thread is ready for execution, which means it can run, but it is not a running thread yet.

Running state (Running)

#When the thread obtains the schedule from the thread scheduler in the JVM, the thread will be in the running state and start The thread execution body that executes the run() method.

Blocked state (Blocked)

This is a thread that is still active but is currently not eligible to run (for some reason, it temporarily gives up on the CPU usage rights, the state when execution is stopped).

Three states in which a thread enters blocking:

1. Waiting for blocking:

1). The thread calls the wait() method to enter the waiting state;

2) Call the join() method to put this thread into another waiting state: waiting for the thread to terminate or time out.

2. Synchronous blocking

The thread will enter this blocking state after failing to obtain a synchronization monitor (held by other threads).

3. Other blocking

Call the sleep() method to actively give up the occupied CPU resources; or call a blocking IO method, issue an I/O request, and enter this blocking state.

Description: The blocked thread will re-enter the ready state at the appropriate time (after the blocking is released) and wait for the thread scheduler to schedule it again.

Death state (Dead)

When exiting the run() method, the thread will die naturally and be in the terminated or dead state, also That ends the life cycle.

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