服务器维护手记-crontab引起大量sendmail进程打死内存问题

来源：互联网发布：软件资源网站编辑：程序博客网时间：2024/06/05 10:29

一大早起来，发现个人网站又报警了，前两天刚加了2G内存，我了个去。。。。

上机器查日志 /var/log/message

Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7539]     0 7539    43237      385   0       0             0 curl
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7540]     0 7540    19602      462   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7541]     0 7541    19601      460   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7542]     0 7542    19602      462   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7543]     0 7543    19603      463   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7544]     0 7544    19601      461   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7545]     0 7545    19602      461   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7546]     0 7546    19602      462   1       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7547]     0 7547    19602      462   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7548]     0 7548    19602      461   0       0             0 sendmail
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7549] 1000 7549    33286     2565   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7550] 1000 7550    33218     2521   1       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7551] 1000 7551    33204     2483   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7552] 1000 7552    33408     2698   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7553] 1000 7553    32843     2071   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7554] 1000 7554    33204     2483   1       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7555] 1000 7555    33205     2454   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7556] 1000 7556    32705     1833   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7557] 1000 7557    32705     1830   1       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7558] 1000 7558    32705     1834   1       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7559]     0 7559    35056      322   0       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7560]     0 7560    35056      322   1       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7561]     0 7561    35056      322   1       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7562]     0 7562    35056      322   1       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7563]     0 7563    35056      322   0       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7564]     0 7564    35056      322   1       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7565]     0 7565    35056      322   1       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7566]     0 7566    35056      322   0       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7567]     0 7567    35056      322   0       0             0 crond
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7568] 1000 7568    32705     1833   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7569] 1000 7569    32704     1641   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7570] 1000 7570    32704     1570   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7571] 1000 7571    32704     1570   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7572] 1000 7572    32704     1545   0       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: [ 7573]     0 7573    32704     1384   1       0             0 httpd
Aug 29 07:31:06 AM9YCYMHJM kernel: Out of memory: Kill process 6525 (mysqld) score 143 or sacrifice child
Aug 29 07:31:06 AM9YCYMHJM kernel: Killed process 6525, UID 27, (mysqld) total-vm:1736764kB, anon-rss:559072kB, file-rss:2044kB

看到内存被打满了，mysql进程又躺枪了(内存耗尽时，内核会选出一个消耗内存最多进程K掉，由于mysql体量大，总是被连累)，看进程信息，发现有很多crond和sendmail

代码里并没有发邮件的东西，忽然想起来昨天晚上加了七八个crontab，且执行频率较高

网上一查，发现确实是这货惹的事，原来crontab执行一次，就给所属者发邮件，邮件发给谁可配置

解决方案：

crontab -e

第一行写入MAILTO=""

表示不发邮件

保存退出

杀掉所有sendmail进程 ps -ef | grep sendmail | grep -v grep | awk '{print $2}' | xargs kill

搞定

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