系统受影响：Ubuntu 16.04、Ubuntu 18.04，而不是 14.04。
频率：大约 大约 24 - 36 小时。
[Wed May 08 03:44:25.964597 2019] [mpm_prefork:notice] [pid 7670] AH00171: Graceful restart requested, doing restart
[Wed May 08 03:44:26.173977 2019] [mpm_prefork:notice] [pid 7670] AH00163: Apache/2.4.39 (Ubuntu) OpenSSL/1.1.1b configured -- resuming normal operations
[Wed May 08 03:44:26.173993 2019] [core:notice] [pid 7670] AH00094: Command line: '/usr/sbin/apache2'
[Wed May 08 03:49:04.001821 2019] [mpm_prefork:notice] [pid 7670] AH00171: Graceful restart requested, doing restart
[Wed May 08 03:49:04.210024 2019] [mpm_prefork:notice] [pid 7670] AH00163: Apache/2.4.39 (Ubuntu) OpenSSL/1.1.1b configured …