strace

Introduction

strace is a program debugging tool in the Linux environment. It is used to trace the system calls of applications. After the strace command is executed, all system calls are displayed in the call sequence, including the function name, parameter list, and return value.

Installation Method

Take CentOS as an example. Run the following command to install the tool:

1	# yum -y install strace

How to Use

Command format: strace [parameter]

Common parameters are as follows:

Parameter	Description
-T	Displays the time consumed by each call.
-tt	Adds time before each line in the output, in microseconds.
-p	Traces ID of the specified thread.

Output format:

18:25:47.902439 epoll_pwait(716, [{EPOLLIN, {u32=1052576880, u64=281463144385648}}, {EPOLLIN, {u32=1052693569, u64=281463144502337}}, {EPOLLOUT, {u32=1052638657, u64=281463144447425}}, {EPOLLIN|EPOLLOUT|EPOLLRDHUP, {u32=1052673241, u64=281463144482009}}, {EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP|EPOLLRDHUP, {u32=1052636016, u64=281463144444784}}], 512, 1, NULL, 8) = 5 <0.000038>

The parameters are described as follows:

Parameter	Description
18:25:47.902439	Indicates the time of the system call.
epoll_pwait	Indicates the name of the function called by the system.
(716...)	The value in the brackets is a function parameter.
=5	Indicates the return value of the system call.
<0.000038>	Indicates the execution time of the system call.

Parent topic: Common Performance Monitoring Tools