在/var/log/apache/error.log上找到了此
[Tue Aug 28 23:07:22.086803 2018] [core:warn] [pid 4642:tid 140536691099520] AH00098: pid file /var/run/apache2/apache2.pid overwritten -- Unclean shutdown of previous Apache run? [Tue Aug 28 23:07:22.087430 2018] [mpm_event:notice] [pid 4642:tid 140536691099520] AH00489: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations [Tue Aug 28 23:07:22.087452 2018] [core:notice] [pid 4642:tid 140536691099520] AH00094: Command line: '/usr/sbin/apache2' [Tue Aug 28 23:07:22.087933 2018] [mpm_event:alert] [pid 4647:tid 140536615016192] (11)Resource temporarily unavailable: apr_thread_create: unable to create worker thread [Tue Aug 28 23:07:22.088191 2018] [mpm_event:alert] [pid 4646:tid 140536615016192] (11)Resource temporarily unavailable: apr_thread_create: unable to create worker thread [Tue Aug 28 23:07:24.089398 2018] [mpm_event:alert] [pid 4642:tid 140536691099520] AH02324: A resource shortage or other unrecoverable failure was encountered before any child process initialized successfully... httpd is exiting! [Tue Aug 28 23:07:50.494617 2018] [core:warn] [pid 4742:tid 139845939062656] AH00098: pid file /var/run/apache2/apache2.pid overwritten -- Unclean shutdown of previous Apache run? [Tue Aug 28 23:07:50.495122 2018] [mpm_event:notice] [pid 4742:tid 139845939062656] AH00489: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations [Tue Aug 28 23:07:50.495138 2018] [core:notice] [pid 4742:tid 139845939062656] AH00094: Command line: '/usr/sbin/apache2' [Tue Aug 28 23:07:50.495467 2018] [mpm_event:alert] [pid 4747:tid 139845862979328] (11)Resource temporarily unavailable: apr_thread_create: unable to create worker thread [Tue Aug 28 23:07:50.495478 2018] [mpm_event:alert] [pid 4746:tid 139845862979328] (11)Resource temporarily unavailable: apr_thread_create: unable to create worker thread [Tue Aug 28 23:07:52.496274 2018] [mpm_event:alert] [pid 4742:tid 139845939062656] AH02324: A resource shortage or other unrecoverable failure was encountered before any child process initialized successfully... httpd is exiting!
我尝试删除，清除和卸载，然后重新安装apt-get install apache2仍然出现相同的错误，所有默认安装和配置
MemTotal: 262144 kB MemFree: 226540 kB Cached: 28040 kB Buffers: 0 kB Active: 58876 kB Inactive: 47080 kB Active(anon): 3392 kB Inactive(anon): 8424 kB Active(file): 55484 kB Inactive(file): 38656 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 11816 kB Shmem: 2776 kB Slab: 7564 kB SReclaimable: 3520 kB SUnreclaim: 4044 kB
Filesystem Size Used Avail Use% Mounted on /dev/simfs 15G 732M 15G 5% / devtmpfs 128M 0 128M 0% /dev tmpfs 128M 0 128M 0% /dev/shm tmpfs 128M 2.8M 126M 3% /run tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 128M 0 128M 0% /sys/fs/cgroup none 128M 0 128M 0% /run/shm