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This article focuses on "how to use ThreadPoolExecutor thread pool in Android". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to use ThreadPoolExecutor thread pool in Android.

Thread pool ThreadPoolExecutor in Android solves the problems of slow efficiency and thread blocking in downloading data by single thread, and its application is also a way to optimize the implementation. So its importance is self-evident, but it is also complex, and there may be problems in understanding, but as an Android engineer, it is inevitable to understand this.

ThreadPoolExecutor has several constructors, and the constructor with the most parameters is the most commonly used. The meaning of each parameter and the relationship between them are described in detail below:

ThreadPoolExecutor (corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler)

The meaning of each parameter:

CorePoolSize: number of core threads, number of tasks that can be executed simultaneously

MaximumPoolSize: excluding the tasks waiting in the buffer queue, the maximum number of tasks that can be held (actually includes the number of core thread pools)

KeepAliveTime: the survival time of a thread placed by workQueue exceeds the survival time of waiting tasks for maximumPoolSize

Unit: unit of time

WorkQueue: blocks the queue of waiting threads, usually using new LinkedBlockingQueue (). If the capacity is not specified, it will be added all the time. If there is no limit, workQueue will never be full.

ThreadFactory: the factory that creates threads, using the system default classes

Handler: when the number of tasks exceeds maximumPoolSize, the default policy for tasks is to refuse to add them.

It should be noted that the handler here is different from the handler in Android.

Perform the process:

When the number of threads is less than corePoolSize, each additional task starts the thread execution immediately.

When the corePoolSize is full, the tasks added later will be put into the buffer queue workQueue to wait.

When the workQueue is full, check whether the number of maximumPoolSize threads is exceeded. If so, execution is refused by default.

To sum up: core thread corePoolSize, task queue workQueue, maximum thread maximumPoolSize, if all three are full, use handler to handle rejected tasks. When the survival time of a thread reaches the specified survival time, the task of the thread has been executed, and the life cycle of the thread ends, the rejected thread can re-enter the thread pool to start the task and cycle the process in turn.

Examples are as follows:

If:

CorePoolSize=2,maximumPoolSize=3,workQueue capacity is 8

At the beginning, the execution of the task corePoolSize B, when the task C has been used up, then C will be put into the buffer queue workQueue waiting, if later added 7 tasks, then workQueue is full, then the number of subsequent tasks is 5 will be compared with maximumPoolSize, because the maximumPoolSize is 3, so can only accommodate 1, because it contains the number of corePollSize, so the following tasks will be rejected by default 4.

At this point, I believe you have a deeper understanding of "how to use the ThreadPoolExecutor thread pool in Android". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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