


Use GDB to debug PHP code and solve the problem of infinite loop of PHP code
Recently, when I was helping my colleagues solve the Swoole Server problem, I found that 1 worker process has been in R state, and The CPU consumption is very high. The preliminary conclusion is that an infinite loop occurs in the PHP code.
The following code shows how to solve the PHP infinite loop problem.
The code is as follows:
#dead_loop.php
$array = array();
for($i = 0; $i {
$array[] = $i;
}
include __DIR__."/include.php";
#include.php
while(1)
{
usleep(10);
$keys = array_flip($array);
$index = array_search(rand(1500, 9999), $array);
$str = str_repeat('A', $index);
$strb = test($index, $str);
}
function test($index, $str)
{
return str_replace('A', 'B', $str);
}
Get the process ID and status through ps aux as follows, use gdb -p process ptrace tracking, and get the call stack through the bt command
The code is as follows:
htf 3834 2.6 0.2 166676 22060 pts/12 R+ 10:50 0:12 php dead_loop.php
gdb -p 3834
(gdb) bt
#0 0x00000000008cc03f in zend_mm_check_ptr (heap=0x1eaa2c0, ptr=0x2584910, silent=1, __zend_filename=0xee3d40 "/home/htf/workspace/php-5.4.27/Zend/zend_variables.c",
__zend_lineno=182, __zend_orig_filename=0xee1888 "/home/htf/workspace/php-5.4.27/Zend/zend_execute_API.c", __zend_orig_lineno=437)
at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:1485
#1 0x000000008cd643 in _zend_mm_free_int (heap = 0x1eaa2c0, P = 0x2584910, __ZEND_FILENAME = 0xee3d40 "/HOMESPACE/php-5.4.27/zend_v ariables.c ", __zend_lineno = 182,
__zend_orig_filename=0xee1888 "/home/htf/workspace/php-5.4.27/Zend/zend_execute_API.c", __zend_orig_lineno=437) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:2064
#2 0x00000000008cebf7 in _efree (ptr=0x2584910, __zend_filename=0xee3d40 "/home/htf/workspace/php-5.4.27/Zend/zend_variables.c", __zend_lineno=182,
__zend_orig_filename=0xee1888 "/home/htf/workspace/php-5.4.27/Zend/zend_execute_API.c", __zend_orig_lineno=437) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:2436
#3 0x00000000008eda0a in _zval_ptr_dtor (zval_ptr=0x25849a0, __zend_filename=0xee3d40 "/home/htf/workspace/php-5.4.27/Zend/zend_variables.c", __zend_lineno=182)
at /home/htf/workspace/php-5.4.27/Zend/zend_execute_API.c:437
#4 0x00000000008fe687 in _zval_ptr_dtor_wrapper (zval_ptr=0x25849a0) at /home/htf/workspace/php-5.4.27/Zend/zend_variables.c:182
#5 0x000000000091259f in zend_hash_destroy (ht=0x7f7263f6e380) at /home/htf/workspace/php-5.4.27/Zend/zend_hash.c:560
#6 0x00000000008fe2c5 in _zval_dtor_func (zvalue=0x7f726426fe50, __zend_filename=0xeea290 "/home/htf/workspace/php-5.4.27/Zend/zend_execute.c", __zend_lineno=901)
at /home/htf/workspace/php-5.4.27/Zend/zend_variables.c:45
#7 0x0000000000936656 in _zval_dtor (zvalue=0x7f726426fe50, __zend_filename=0xeea290 "/home/htf/workspace/php-5.4.27/Zend/zend_execute.c", __zend_lineno=901)
at /home/htf/workspace/php-5.4.27/Zend/zend_variables.h:35
#8 0x0000000000939747 in zend_assign_to_variable (variable_ptr_ptr=0x7f7263f8e738, value=0x7f726426f6a8) at /home/htf/workspace/php-5.4.27/Zend/zend_execute.c:901
#9 0x0000000000997ee5 in ZEND_ASSIGN_SPEC_CV_VAR_HANDLER (execute_data=0x7f726d04b2a8) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:33168
#10 0x000000000093b5fd in execute (op_array=0x21d58b0) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:410
#11 0x0000000000901692 in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/htf/workspace/php-5.4.27/Zend/zend.c:1315
#12 0x000000000087926a in php_execute_script (primary_file=0x7ffffe0038d0) at /home/htf/workspace/php-5.4.27/main/main.c:2502
#13 0x00000000009a32e3 in do_cli (argc=2, argv=0x7ffffe004d18) at /home/htf/workspace/php-5.4.27/sapi/cli/php_cli.c:989
#14 0x00000000009a4491 in main (argc=2, argv=0x7ffffe004d18) at /home/htf/workspace/php-5.4.27/sapi/cli/php_cli.c:1365
After executing gdb, the endless loop process will change to T status, indicating that it is Trace. This is exclusive, so you can no longer use strace/gdb or other ptrace tools to debug this process. Additionally this process will interrupt execution. After gdb enters c, the program continues to run downward. Then press ctrl+c again to interrupt the program. View the call stack of the process through the bt command.
The code is as follows:
(gdb) bt
#0 _zend_mm_alloc_int (heap=0x1eaa2c0, size=72, __zend_filename=0xe43410 "/home/htf/workspace/php-5.4.27/ext/standard/array.c", __zend_lineno=2719,
__zend_orig_filename=0xee5a38 "/home/htf/workspace/php-5.4.27/Zend/zend_hash.c", __zend_orig_lineno=412) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:1895
#1 0x00000000008ceb86 in _emalloc (size=72, __zend_filename=0xe43410 "/home/htf/workspace/php-5.4.27/ext/standard/array.c", __zend_lineno=2719,
__zend_orig_filename=0xee5a38 "/home/htf/workspace/php-5.4.27/Zend/zend_hash.c", __zend_orig_lineno=412) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:2425
#2 0x0000000000911d85 in _zend_hash_index_update_or_next_insert (ht=0x2257a10, h=3972, pData=0x7ffffe0012b0, nDataSize=8, pDest=0x0, flag=1,
__zend_filename=0xe43410 "/home/htf/workspace/php-5.4.27/ext/standard/array.c", __zend_lineno=2719) at /home/htf/workspace/php-5.4.27/Zend/zend_hash.c:412
#3 0x00000000007767e1 in zif_array_flip (ht=1, return_value=0x7f726424ea68, return_value_ptr=0x0, this_ptr=0x0, return_value_used=1)
at /home/htf/workspace/php-5.4.27/ext/standard/array.c:2719
#4 0x000000000093c03e in zend_do_fcall_common_helper_SPEC (execute_data=0x7f726d04b2a8) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:643
#5 0x00000000009400e6 in ZEND_DO_FCALL_SPEC_CONST_HANDLER (execute_data=0x7f726d04b2a8) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:2233
#6 0x000000000093b5fd in execute (op_array=0x21d58b0) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:410
两次的BT信息不一样,这是因为程序在不同的位置中断。看到execute (oparray=0x21d58b0) 这一行,这里就是PHP执行oparray的入口了。gdb下输入f 6,(通过调用栈编号可得)。
代码如下:
(gdb) f 6
#6 0x000000000093b5fd in execute (op_array=0x21d58b0) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:410
410 if ((ret = OPLINE->handler(execute_data TSRMLS_CC)) > 0) {
(gdb) p *op_array
$2 = {type = 2 '

命名管道是一种在操作系统中相对比较低级的进程通信方式,它是一种以文件为中介的进程通信方式。在Go语言中,通过os包提供了对命名管道的支持。在本文中,我们将介绍如何在Go中使用命名管道来实现进程间通信。一、命名管道的概念命名管道是一种特殊的文件,可以被多个进程同时访问。在Linux系统中,命名管道是一种特殊的文件类型,它们存在于文件系统的某个位置上,并且可以在

在Go语言中,使用第三方库是非常方便的。许多优秀的第三方库和框架可以帮助我们快速地开发应用程序,同时也减少了我们自己编写代码的工作量。但是如何正确地使用第三方库,确保其稳定性和可靠性,是我们必须了解的一个问题。本文将从以下几个方面介绍如何使用第三方库,并结合具体例子进行讲解。一、第三方库的获取Go语言中获取第三方库有以下两种方式:1.使用goget命令首先

随着传统的多线程模型在高并发场景下的性能瓶颈,协程成为了PHP编程领域的热门话题。协程是一种轻量级的线程,能够在单线程中实现多任务的并发执行。在PHP的语言生态中,协程得到了广泛的应用,比如Swoole、Workerman等框架就提供了对协程的支持。那么,如何在PHP中使用协程呢?本文将介绍一些基本的使用方法以及常见的注意事项,帮助读者了解协程的运作原理,以

变量函数是指可以使用变量来调用函数的一种特殊语法。在PHP中,变量函数是非常有用的,因为它可以让我们更加灵活地使用函数。在本文中,我们将介绍如何在PHP中使用变量函数。定义变量函数在PHP中,变量函数的定义方式非常简单,只需要将要调用的函数名赋值给一个变量即可。例如,下面的代码定义了一个变量函数:$func='var_dump';这里将var_dump函

<p>Windows 系统上的 OneDrive 应用程序允许您将文件存储在高达 5 GB 的云上。OneDrive 应用程序中还有另一个功能,它允许用户选择一个选项,是将文件保留在系统空间上还是在线提供,而不占用您的系统存储空间。此功能称为按需文件。在这篇文章中,我们进一步探索了此功能,并解释了有关如何在 Windows 11 电脑上的 OneDrive 中按需使用文件的各种选项。</p><h2>如何使用 On

数据聚合函数是一种用于处理数据库表中多行数据的函数。在PHP中使用数据聚合函数可以使得我们方便地进行数据分析和处理,例如求和、平均数、最大值、最小值等。下面将介绍如何在PHP中使用数据聚合函数。一、介绍常用的数据聚合函数COUNT():计算某一列的行数。SUM():计算某一列的总和。AVG():计算某一列的平均值。MAX():取出某一列的最大值。MIN():

近年来,WebSocket技术已经成为了Web开发中不可或缺的一部分。WebSocket是一种在单个TCP连接上进行全双工通信的协议,它使得客户端和服务器之间的通信更加流畅和高效。如今,很多现代的Web应用程序都使用了WebSocket技术,例如实时聊天、在线游戏以及实时数据可视化等。Go语言作为一个现代的编程语言,自然也提供了很好的支持WebSock

随着音频处理在各种应用场景中的普及,越来越多的程序员开始使用Go编写音频处理程序。Go语言作为一种现代化的编程语言,具有优秀的并发性和高效率的特点,使用它进行音频处理十分方便。本文将介绍如何在Go中使用音频处理技术,包括读取、写入、处理和分析音频数据等方面的内容。一、读取音频数据在Go中读取音频数据有多种方式。其中比较常用的是使用第三方库进行读取,比如go-


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

SublimeText3 English version
Recommended: Win version, supports code prompts!

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft
