What is thread scheduling in java

In Java, executing multiple threads on a single CPU in a certain order is called scheduling; it is the core of multi-threading. Having a good thread scheduling can give full play to system performance and efficient Utilize CPU resources to improve program execution efficiency.

Normally, the runnable thread with the highest priority will run first and is active (running); if a high-priority thread is awakened and is running If a low-priority thread is used, the high-priority thread will run immediately. [Recommended related video tutorials: Java tutorial]

Scheduling type

1. Waiting and notification

Waiting [wait()] and notification [notify(), notifyAll()] provide a way to communicate between threads synchronized on the same object.

Description:

wait() method: When the wait() method is called on an object, the thread executing the code immediately gives up the lock on the object and moves the thread to wait state.

notify() method: This wakes up the thread that called wait() on the same object and moves the thread to the ready state.

notifyAll() method: This will wake up all threads that call wait() on the same object.

2. Run and Yield

The Yield() method is used to provide execution opportunities for other threads with the same priority, that is, to move the currently running thread to an available Operating status.

3. Sleep and enable

nSleep() method is used to pause the thread for a specified period of time, that is, move the currently running thread to the Sleep state for a specified period of time. Then move it to the runnable state. Example:

Thread.sleep（毫秒数）;

Thread priority

Each thread has a priority, which is an integer number between 1 and 10 Indicates that the higher the number, the higher the priority, and the thread priority defaults to 5. In most cases, the thread scheduler schedules threads based on their priority (called preemptive scheduling).

When you create a Java thread, it inherits its priority from the thread that created it; we can also use the setPriority method to modify the thread's priority at any time after creating the thread. .

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