关于本章

multitasking是Linux OS的核心特性，本章将对它与它相关的programming进行描述。

Thread functions and the process functions

在APUE 11.5 Thread Termination中总结了“similarities between the thread functions and the process functions”

By now, you should begin to see similarities between the thread functions and the process functions. Figure 11.6 summarizes the similar functions.

Process primitive	Thread primitive	Description
fork	pthread_create	create a new flow of control
exit	pthread_exit	exit from an existing flow of control
waitpid	pthread_join	get exit status from flow of control
atexit	pthread_cleanup_push	register function to be called at exit from flow of control
getpid	pthread_self	get ID for flow of control
abort	pthread_cancel	request abnormal termination of flow of control

Figure 11.6 Comparison of process and thread primitives

Fork-join model

在工程parallel-computing的Model\Fork–join-model.md中总结了Fork–join model，可以看到上述thread functions和process functions显然是遵循这种model的：

下面是草稿

fork api：

entity	api
process	fork
thread	pthread_create

join api

entity	api
process	WAIT(2)、WAIT4(2)
thread	PTHREAD_JOIN(3)、pthread_barrier_wait(3)

clone

之前已经谈论了Linux OS中process、thread的实现，我们已经知道: 它们都依赖于clone system call，这是Linux OS中，非常重要的一个system call，我们将它单独放到一个章节中进行描述。