python-多线程(原理篇)

时间:2021-06-15 19:00:38

多线程的基本概念

语言学习总是绕不过一些东西,例如多进程和多线程,最近越来越发现,上来看几个实例练习一下过几天就不知其所以然了。所以还是先看看原理,在看实例练习吧!

线程的概念

概念:线程是进程中执行运算的最小单位,是进程中的一个实体,是被系统独立调度和分派的基本单位,线程自己不拥有系统资源,只拥有一点在运行中必不可少的资源,但它可与同属一个进程的其它线程共享进程所拥有的全部资源。一个线程可以创建和撤消另一个线程,同一进程中的多个线程之间可以并发执行。其实平时我们启动程序,其实是启动的进程,但是在往下细分的话,其实是进程的一个或者多个线程完成的功能。

好处 :(1)易于调度。

(2)提高并发性。通过线程可方便有效地实现并发性。进程可创建多个线程来执行同一程序的不同部分。

(3)开销少。创建线程比创建进程要快,所需开销很少。

(4)利于充分发挥多处理器的功能。通过创建多线程进程,每个线程在一个处理器上运行,从而实现应用程序的并发性,使每个处理器都得到充分运行。

多线程vs多进程

操作系统会为每个进程分配不同的内存块,而多个线程共享进程的内存块。这带来最直接的不同就是创建线程的开销远小于创建进程的开销。

同时,由于内存块不同,所以进程之间的通信相对困难。而线程间的通信简单快速,就是共享进程内的全局变量。

但是,进程的调度由操作系统负责,线程的调度需要我们自己来考虑,避免死锁,饥饿,活锁,资源枯竭等情况的发生,这会增加一定的复杂度,这会增加一定的复杂度。而且,由于线程之间共享内存,我们还需要考虑线程安全性的问题。

线程安全

以为线程间共享进程中的全局变量,所以当其他线程改变了共享的变量时,可能会对本线程产生影响。所谓线程安全的约束是指一个函数被多个并发线程反复调用时,要一直产生正确的结果。要保证线程安全,主要是通过加锁的方式保证共享变量的正确访问。

比线程安全更严格的约束是‘可重入性’,即函数在一个线程内执行的工程中被暂停,接下来又在另一个线程内被调用,之后在返回原线程继续执行。在整个过程中都能保证正确执行。保证可重入性,通常通过制作全局变量的本地拷贝来实现。

线程的生命周期

线程的生命周期如下图所示

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*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" alt="" />

各个状态的说明如下:

1.new新建。新创建的线程经过初始化后,进入Runnable状态。

2.Runnable就绪。等待线程调度。调度后进入运行状态。

3.Running运行。

4.Blocked阻塞,暂停运行,解除阻塞后进入Runnable状态重新等待调度。

5.Dead消亡。线程方法执行完毕返回或者异常终止。

可能有3种情况从Running进入Blocked:

  • 同步:线程中获取同步锁,但是资源已经被其他线程锁定时,进入Locked状态,直到该资源可获取(获取的顺序由Lock队列控制)
  • 睡眠:线程运行sleep()或join()方法后,线程进入Sleeping状态。区别在于sleep等待固定的时间,而join是等待子线程执行完。当然join也可以指定一个“超时时间”。从语义上来说,如果两个线程a,b, 在a中调用b.join(),相当于合并(join)成一个线程。最常见的情况是在主线程中join所有的子线程。
  • 等待:线程中执行wait()方法后,线程进入Waiting状态,等待其他线程的通知(notify)。

线程的类型

  • 主线程:当一个程序启动时,就有一个进程被操作系统(OS)创建,与此同时一个线程也立刻运行,该线程通常叫做程序的主线程(Main Thread)。每个进程至少都有一个主线程,主线程通常最后关闭。
  • 子线程:在程序中创建的其他线程,相对于主线程来说就是这个主线程的子线程。
  • 守护线程:daemon thread,对线程的一种标识。守护线程为其他线程提供服务,如JVM的垃圾回收线程。当剩下的全是守护线程时,进程退出。
  • 前台线程:相对于守护线程的其他线程称为前台线程。