编译时-pthread和-lpthread之间的区别 [英] Difference between -pthread and -lpthread while compiling

问题描述

在编译多线程程序时使用 gcc -pthread 和 gcc -lpthread 有什么区别？

解决方案>

作为配置线程的编译。例如，下面显示了在GCC包上使用 -pthread 选项时定义的宏安装在我的Ubuntu机器上：

pre $ gcc -pthread -E -dM test.c> dm.pthread.txt
$ gcc -E -dM test.c> dm.nopthread.txt
$ diff dm.pthread.txt dm.nopthread.txt
152d151
< #define _REENTRANT 1
208d206
< #define __USE_REENTRANT 1

使用 -lpthread 选项只会导致pthread库被链接 - 预定义的宏不会被定义。

底线：您应该使用 - pthread 选项。

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注意： -pthread 选项在GCC文档中记录为特定于平台的选项，因此它可能并不总是可用的。但是，它可以在GCC文档没有明确列出的平台上使用（例如i386和x86-64） - 您应该在可用时使用它。

还要注意，GCC已经使用了其他类似的选项，例如 -pthreads （作为 -pthread 的同义词列出）在Solaris 2上）和 -mthread （对于i386和x86-64 Windows上的MinGW特定线程支持）。我的理解是，GCC正在努力转向使用 -pthread 一律前进。

What is the difference between gcc -pthread and gcc -lpthread which is used while compiling multithreaded programs?

解决方案

-pthread tells the compiler to link in the pthread library as well as configure the compilation for threads.

For example, the following shows the macros that get defined when the -pthread option gets used on the GCC package installed on my Ubuntu machine:

$ gcc -pthread -E -dM test.c > dm.pthread.txt
$ gcc          -E -dM test.c > dm.nopthread.txt
$ diff dm.pthread.txt dm.nopthread.txt 
152d151
< #define _REENTRANT 1
208d206
< #define __USE_REENTRANT 1

Using the -lpthread option only causes the pthread library to be linked - the pre-defined macros don't get defined.

Bottom line: you should use the -pthread option.

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Note: the -pthread option is documented as a platform specific option in the GCC docs, so it might not always be available. However, it is available on platforms that the GCC docs don't explicitly list it for (such as i386 and x86-64) - you should use it when available.

Also note that other similar options have been used by GCC, such as -pthreads (listed as a synonym for -pthread on Solaris 2) and -mthread (for MinGW-specific thread support on i386 and x86-64 Windows). My understanding is that GCC is trying to move to using -pthread uniformly going forward.

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