☰

systemd 是否支持分叉守护进程的故障重启？

tag-icon • tag-icon systemd exit-status
systemd 是否支持分叉守护进程的故障重启？

起初发布在 StackOverflow 上，告诉你过来询问。回顾一下那次谈话——

  1. 不，我还没有真正能够尝试进行更改以查看会发生什么（可能会影响正在运行的生产服务）。
  2. RTFM 尽职调查已完成。他们不涉及这个。

我原来的问题如下：

systemd假设我的单元文件中有以下内容：

Type=forking
Restart=on-failure

父进程退出，状态为 0（子进程成功启动）。在稍后的某个时刻，孩子以非零状态死亡。会发生什么？ systemd可以跟踪子守护进程PID：

Process: 1768 ExecStart=/bin/mydaemon (code=exited, status=0/SUCCESS)
Main PID: 1770 (mydaemon)

是Restart=on-failure只看parent退出状态，还是也看child？

答案1

我创建了以下单元文件：

[Unit]
Description=Something

[Service]
Type=forking
WorkingDirectory=/tmp
ExecStart=/tmp/script.sh
ExecStop=/tmp/script.sh
Restart=on-failure

script.sh 包含以下内容：

#!/bin/sh
echo "Forking"
/tmp/myscript.sh &

myscript.sh 包含以下内容：

#!/bin/sh
sleep 60
exit 1

果然，每隔 60 秒，systemd 就会重新启动该服务。

如图所示，注意不同的 PID 和开始时间，注意它会重新启动父进程：

linux:~ # systemctl status myService.service
● myService.service - Something
   Loaded: loaded (/etc/systemd/system/myService.service; static; vendor preset: disabled)
   Active: active (running) since Mon 2017-07-10 20:43:29 CEST; 57s ago
  Process: 4393 ExecStart=/tmp/script.sh (code=exited, status=0/SUCCESS)
 Main PID: 4396 (script.sh)
    Tasks: 2 (limit: 512)
   CGroup: /system.slice/myService.service
           ├─4396 /bin/sh /tmp/script.sh
           └─4397 sleep 60

Jul 10 20:43:29 linux.suse systemd[1]: Starting Something...
Jul 10 20:43:29 linux.suse script.sh[4393]: Forking
Jul 10 20:43:29 linux.suse systemd[1]: Started Something.
linux:~ # systemctl status myService.service
● myService.service - Something
   Loaded: loaded (/etc/systemd/system/myService.service; static; vendor preset: disabled)
   Active: active (running) since Mon 2017-07-10 20:44:29 CEST; 1s ago
  Process: 4409 ExecStop=/tmp/script.sh (code=exited, status=0/SUCCESS)
  Process: 4417 ExecStart=/tmp/script.sh (code=exited, status=0/SUCCESS)
 Main PID: 4420 (script.sh)
    Tasks: 2 (limit: 512)
   CGroup: /system.slice/myService.service
           ├─4420 /bin/sh /tmp/script.sh
           └─4421 sleep 60

Jul 10 20:44:29 linux.suse systemd[1]: Starting Something...
Jul 10 20:44:29 linux.suse script.sh[4417]: Forking
Jul 10 20:44:29 linux.suse systemd[1]: Started Something.

相关内容