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[Nginx] 详解php+nginx 服务发生500 502错误排查思路

web服务器 web服务器 发布于:2021-08-11 11:19 | 阅读数:280 | 评论:0

概述
当线上的服务中访问中出现500或者502错误时,需要紧急处理,排查问题,该怎么做?可以通过分析一些错误日志或者跟踪php-fpm进程来进行问题定位。
nginx error_log
nginx的error_log在nginx的配置文件中定义的
server {
 listen  80;
 server_name localhost;
 root   /var/www;
 
 access_log /Users/jiao/logs/default.access.log;
 error_log /Users/jiao/logs/default.error.log;
 location / {
  index index.html index.htm index.php;
  autoindex on;
 }
 location = /info {
  allow 127.0.0.1;
  deny all;
  rewrite (.*) /.info.php;
 }
 location ~ \.php$ {
  root /var/www;
  fastcgi_pass 127.0.0.1:9000;
  fastcgi_index index.php;
  fastcgi_param SCRIPT_FILENAME /var/www$fastcgi_script_name;
  include /usr/local/etc/nginx/fastcgi_params;
 }
}
查看error_log
➜  tail /Users/jiao/logs/default.error.log
2019/07/17 11:08:18 [error] 77416#0: *76 kevent() reported about an closed connection (54: Connection reset by peer) while reading response header from upstream, client: 127.0.0.1, server: localhost, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "localhost"
发现出现了Connection reset by peer,连接被重置了,此时可以再查看php-fpm的error_log进一步分析问题
php-fpm error_log
php-fpm的error_log在php-fpm.conf文件中配置中定义的
; Error log file
; If it's set to "syslog", log is sent to syslogd instead of being written
; in a local file.
; Note: the default prefix is /usr/local/var
; Default Value: log/php-fpm.log
error_log = log/php-fpm.log
error_log里面的内容是这样的
➜ tail /usr/local/var/log/php-fpm.log
[17-Jul-2019 10:49:54] NOTICE: [pool www] child 81948 started
[17-Jul-2019 11:08:18] WARNING: [pool www] child 77537, script '/var/www/index.php' (request: "GET /index.php") execution timed out (3.801267 sec), terminating
[17-Jul-2019 11:08:18] WARNING: [pool www] child 77537 exited on signal 15 (SIGTERM) after 1503.113967 seconds from start
[17-Jul-2019 11:08:18] NOTICE: [pool www] child 94339 started
可以看到是请求/var/www/index.php文件出现了超时
dtruss
dtruss是动态跟踪命令,可以根据PID,name跟踪进程
mac环境下使用dtruss,linux环境可以使用strace,pstack
➜ dtruss 
USAGE: dtruss [-acdefholLs] [-t syscall] { -p PID | -n name | command | -W name }
-p PID   # examine this PID
-n name   # examine this process name
-t syscall  # examine this syscall only
-W name   # wait for a process matching this name
-a  # print all details
-c  # print syscall counts
-d  # print relative times (us)
-e  # print elapsed times (us)
-f  # follow children
-l  # force printing pid/lwpid
-o  # print on cpu times
-s  # print stack backtraces
-L  # don't print pid/lwpid
-b bufsize  # dynamic variable buf size
eg,
dtruss df -h  # run and examine "df -h"
dtruss -p 1871  # examine PID 1871
dtruss -n tar  # examine all processes called "tar"
dtruss -f test.sh # run test.sh and follow children
跟踪php-fpm:sudo dtruss -a -n php-fpm
此时访问web页面,就可以看到跟踪内容
21416/0x3479b6:  1559  63  3 getrusage(0x0, 0x7FFEE1EC0760, 0x0)   = 0 0
21416/0x3479b6:  1561  4  0 getrusage(0xFFFFFFFFFFFFFFFF, 0x7FFEE1EC0760, 0x0)   = 0 0
21416/0x3479b6:  1627  77  17 poll(0x7FFEE1EC08C0, 0x1, 0x1388)   = 1 0
dtrace: error on enabled probe ID 2174 (ID 159: syscall::read:return): invalid kernel access in action #13 at DIF offset 68
dtrace: error on enabled probe ID 2174 (ID 159: syscall::read:return): invalid kernel access in action #13 at DIF offset 68
dtrace: error on enabled probe ID 2174 (ID 159: syscall::read:return): invalid kernel access in action #13 at DIF offset 68
dtrace: error on enabled probe ID 2174 (ID 159: syscall::read:return): invalid kernel access in action #13 at DIF offset 68
dtrace: error on enabled probe ID 2174 (ID 159: syscall::read:return): invalid kernel access in action #13 at DIF offset 68
21416/0x3479b6:  1872  29  24 lstat64("/var/www/index.php\0", 0x7FFEE1ECFF38, 0x0)   = 0 0
21416/0x3479b6:  1884  9  6 lstat64("/var/www\0", 0x7FFEE1ECFDF8, 0x0)   = 0 0
21416/0x3479b6:  1889  6  3 lstat64("/var\0", 0x7FFEE1ECFCB8, 0x0)   = 0 0
21416/0x3479b6:  1899  12  8 readlink("/var\0", 0x7FFEE1ED0090, 0x400)   = 11 0
21416/0x3479b6:  1905  6  4 lstat64("/private/var\0", 0x7FFEE1ECFB78, 0x0)   = 0 0
21416/0x3479b6:  1917  6  3 lstat64("/private\0", 0x7FFEE1ECFA38, 0x0)   = 0 0
21416/0x3479b6:  2178  18  14 stat64("/var/www/.user.ini\0", 0x7FFEE1ED0240, 0x0)   = -1 Err#2
21416/0x3479b6:  2217  5  1 setitimer(0x2, 0x7FFEE1ED07E0, 0x0)   = 0 0
21416/0x3479b6:  2225  4  0 sigaction(0x1B, 0x7FFEE1ED0788, 0x7FFEE1ED07B0)   = 0 0
21416/0x3479b6:  2237  5  1 sigprocmask(0x2, 0x7FFEE1ED0804, 0x0)   = 0x0 0
21416/0x3479b6:  3643  48  40 open_nocancel(".\0", 0x0, 0x1)   = 5 0
21416/0x3479b6:  3648  7  3 fstat64(0x5, 0x7FFEE1ED0110, 0x0)   = 0 0
21416/0x3479b6:  3653  7  2 fcntl_nocancel(0x5, 0x32, 0x10F252158)   = 0 0
21416/0x3479b6:  3661  12  7 close_nocancel(0x5)   = 0 0
21416/0x3479b6:  3670  10  7 stat64("/usr/local/var\0", 0x7FFEE1ED0080, 0x0)   = 0 0
21416/0x3479b6:  3681  11  8 chdir("/var/www\0", 0x0, 0x0)   = 0 0
21416/0x3479b6:  3698  4  0 setitimer(0x2, 0x7FFEE1ED02D0, 0x0)   = 0 0
21416/0x3479b6:  3710  6  3 fcntl(0x3, 0x8, 0x10F3FD858)   = 0 0
21416/0x3479b6:  3733  9  6 stat64("/private/var/www/index.php\0", 0x7FFEE1ECFF10, 0x0)   = 0 0
74904/0x332630: 723125 1073381  19 kevent(0x9, 0x0, 0x0)   = 0 0
74902/0x332629: 770666 1073387  17 kevent(0x8, 0x0, 0x0)   = 0 0
74904/0x332630: 723165 1061954  20 kevent(0x9, 0x0, 0x0)   = 0 0
74902/0x332629: 770709 1061954  20 kevent(0x8, 0x0, 0x0)   = 0 0
74904/0x332630: 723201 1074786  16 kevent(0x9, 0x0, 0x0)   = 0 0
74902/0x332629: 770747 1074783  16 kevent(0x8, 0x0, 0x0)   = 0 0
74904/0x332630: 723229 1069141  13 kevent(0x9, 0x0, 0x0)   = 0 0
74902/0x332629: 770777 1069145  11 kevent(0x8, 0x0, 0x0)   = 0 0
21416/0x3479b6:  3942 3902233  7 __semwait_signal(0x703, 0x0, 0x1)   = -1 Err#4
74902/0x332629: 770814  103  25 kill(21416, 15)   = 0 0
dtrace: error on enabled probe ID 2172 (ID 161: syscall::write:return): invalid kernel access in action #13 at DIF offset 68
dtrace: error on enabled probe ID 2172 (ID 161: syscall::write:return): invalid kernel access in action #13 at DIF offset 68
74902/0x332629: 771325  7  2 sigreturn(0x7FFEE1ECFC40, 0x1E, 0xC1A4B78E0404663A)   = 0 Err#-2
74902/0x332629: 771336  7  3 kevent(0x8, 0x0, 0x0)   = 1 0
dtrace: error on enabled probe ID 2174 (ID 159: syscall::read:return): invalid kernel access in action #13 at DIF offset 68
74902/0x332629: 771352  11  7 wait4(0xFFFFFFFFFFFFFFFF, 0x7FFEE1ED0748, 0x3)   = 21416 0
dtrace: error on enabled probe ID 2172 (ID 161: syscall::write:return): invalid kernel access in action #13 at DIF offset 68
74902/0x332629: 773511 1957 1899 fork()   = 28060 0
28060/0x3754c5:  125:  0:  0 fork()   = 0 0
28060/0x3754c5:  128  9  2 bsdthread_register(0x7FFF6774C418, 0x7FFF6774C408, 0x2000)   = -1 Err#22
dtrace: error on enabled probe ID 2172 (ID 161: syscall::write:return): invalid kernel access in action #13 at DIF offset 68
74902/0x332629: 773737  4  1 wait4(0xFFFFFFFFFFFFFFFF, 0x7FFEE1ED0748, 0x3)   = 0 0
74902/0x332629: 773742  6  3 read(0x5, "\0", 0x1)   = -1 Err#35
28060/0x3754c5:  320  4  0 getpid(0x0, 0x0, 0x0)   = 28060 0
28060/0x3754c5:  328  7  2 __mac_syscall(0x7FFF67758A17, 0x4, 0x7FFEE1ED0208)   = -1 Err#45
28060/0x3754c5:  332  5  2 csops(0x6D9C, 0xB, 0x7FFEE1ED0248)   = -1 Err#22
28060/0x3754c5:  755  14  11 dup2(0x1, 0x2, 0x0)   = 2 0
28060/0x3754c5:  797  89  22 close(0x4)   = 0 0
28060/0x3754c5:  806  11  6 dup2(0x7, 0x0, 0x0)   = 0 0
28060/0x3754c5:  817  4  0 geteuid(0x0, 0x0, 0x0)   = 501 0
28060/0x3754c5:  820  3  0 close(0x5)   = 0 0
28060/0x3754c5:  821  3  0 close(0x6)   = 0 0
28060/0x3754c5:  824  5  1 sigaction(0xF, 0x7FFEE1ED0688, 0x0)   = 0 0
28060/0x3754c5:  825  3  0 sigaction(0x2, 0x7FFEE1ED0688, 0x0)   = 0 0
28060/0x3754c5:  827  3  0 sigaction(0x1E, 0x7FFEE1ED0688, 0x0)   = 0 0
28060/0x3754c5:  828  3  0 sigaction(0x1F, 0x7FFEE1ED0688, 0x0)   = 0 0
28060/0x3754c5:  829  3  0 sigaction(0x14, 0x7FFEE1ED0688, 0x0)   = 0 0
28060/0x3754c5:  830  3  0 sigaction(0x3, 0x7FFEE1ED0688, 0x0)   = 0 0
28060/0x3754c5:  1043  3  0 close(0x7)   = 0 0
可以看到系统底层执行的函数,如lstat64获取文件内容信息,kill(21416, 15)kill掉php-fpm进程,fork()出新的php-fpm进程,有兴趣可以深入研究每个指令的作用
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://segmentfault.com/a/1190000019788534

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