几个月以来，我的 2GB RAM VPS Linode 服务器一直出现随机崩溃的情况。有人劝我改用自托管主机，出于某种原因，我认为我可以处理它，尽管我在这方面没有经验。我将提供尽可能多的信息来提供帮助：
所讨论的网站是一个 Wordpress/Woocommerce 网站，它确实有很多插件，所以我知道这不是理想的，但它们大多是必需的。并发用户通常在 10 左右，实际上不会超过 20。我注意到我确实倾向于让很多随机机器人访问我的网站，有时会导致流量激增，但我觉得即使是这样也应该是可控的，因为我已经设置了 CDN 和 w3cache。该网站 99% 的时间运行顺畅，没有问题。我甚至使用 loadimpact.com 运行了负载测试，服务器处理得很好。
以下是最近一次崩溃的一些日志，也许有人可以从中得到一些线索：
错误日志
[Fri Jun 19 03:06:07 2015] [error] server reached MaxClients setting, consider raising the MaxClients setting
MYSQL 日志
150619 03:06:09 mysqld_safe Number of processes running now: 0
150619 03:06:12 mysqld_safe mysqld restarted
150619 3:06:15 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
150619 3:06:15 [Note] Plugin 'FEDERATED' is disabled.
150619 3:06:15 InnoDB: The InnoDB memory heap is disabled
150619 3:06:15 InnoDB: Mutexes and rw_locks use GCC atomic builtins
150619 3:06:15 InnoDB: Compressed tables use zlib 1.2.3
150619 3:06:15 InnoDB: Using Linux native AIO
150619 3:06:16 InnoDB: Initializing buffer pool, size = 320.0M
150619 3:06:16 InnoDB: Completed initialization of buffer pool
150619 3:06:17 InnoDB: highest supported file format is Barracuda.
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
150619 3:06:17 InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
系统日志信息
Jun 19 03:06:07 panel kernel: php invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
Jun 19 03:06:07 panel kernel: php cpuset=/ mems_allowed=0
Jun 19 03:06:07 panel kernel: CPU: 1 PID: 24844 Comm: php Not tainted 4.0.5-x86_64-linode58 #1
Jun 19 03:06:07 panel kernel: 0000000000000000 ffff880055fac740 ffffffff8193b626 ffff880055fac100
Jun 19 03:06:07 panel kernel: ffffffff819360a4 0100000000000400 ffff88007fc17000 0000000000000020
Jun 19 03:06:07 panel kernel: ffff88007fc17000 0000000000000000 0000000000000000 0000000000000000
Jun 19 03:06:07 panel kernel: Call Trace:
Jun 19 03:06:07 panel kernel: [<ffffffff8193b626>] ? dump_stack+0x40/0x50
Jun 19 03:06:07 panel kernel: [<ffffffff819360a4>] ? dump_header.isra.10+0x78/0x1e3
Jun 19 03:06:07 panel kernel: [<ffffffff81941bb6>] ? _raw_spin_unlock_irqrestore+0x2e/0x3f
Jun 19 03:06:07 panel kernel: [<ffffffff81172f4a>] ? oom_kill_process+0xbe/0x380
Jun 19 03:06:07 panel kernel: [<ffffffff810dc57d>] ? has_ns_capability_noaudit+0x13/0x1b
Jun 19 03:06:07 panel kernel: [<ffffffff8117369a>] ? __out_of_memory+0x43d/0x47d
Jun 19 03:06:07 panel kernel: [<ffffffff8117381b>] ? out_of_memory+0x52/0x67
Jun 19 03:06:07 panel kernel: [<ffffffff811777e5>] ? __alloc_pages_nodemask+0x708/0x846
Jun 19 03:06:07 panel kernel: [<ffffffff811a4a7d>] ? alloc_pages_current+0xb2/0xcf
Jun 19 03:06:07 panel kernel: [<ffffffff8117205d>] ? filemap_fault+0x26f/0x394
Jun 19 03:06:07 panel kernel: [<ffffffff8118f78d>] ? __do_fault+0x3f/0x79
Jun 19 03:06:07 panel kernel: [<ffffffff81193009>] ? handle_mm_fault+0x370/0xd80
Jun 19 03:06:07 panel kernel: [<ffffffff811426a1>] ? __audit_syscall_exit+0x208/0x224
Jun 19 03:06:07 panel kernel: [<ffffffff8104219d>] ? __do_page_fault+0x321/0x37b
Jun 19 03:06:07 panel kernel: [<ffffffff81943f08>] ? page_fault+0x28/0x30
Jun 19 03:06:07 panel kernel: Mem-Info:
Jun 19 03:06:07 panel kernel: Node 0 DMA per-cpu:
Jun 19 03:06:07 panel kernel: CPU 0: hi: 0, btch: 1 usd: 0
Jun 19 03:06:07 panel kernel: CPU 1: hi: 0, btch: 1 usd: 0
Jun 19 03:06:07 panel kernel: Node 0 DMA32 per-cpu:
Jun 19 03:06:07 panel kernel: CPU 0: hi: 186, btch: 31 usd: 3
Jun 19 03:06:07 panel kernel: CPU 1: hi: 186, btch: 31 usd: 0
Jun 19 03:06:07 panel kernel: active_anon:348396 inactive_anon:116687 isolated_anon:32
Jun 19 03:06:07 panel kernel: active_file:351 inactive_file:528 isolated_file:0
Jun 19 03:06:07 panel kernel: unevictable:0 dirty:0 writeback:6 unstable:0
Jun 19 03:06:07 panel kernel: free:3411 slab_reclaimable:8339 slab_unreclaimable:5537
Jun 19 03:06:07 panel kernel: mapped:169339 shmem:168953 pagetables:8887 bounce:0
Jun 19 03:06:07 panel kernel: free_cma:0
Jun 19 03:06:07 panel kernel: Node 0 DMA free:7928kB min:44kB low:52kB high:64kB active_anon:2880kB inactive_anon:3140kB active_file:0kB inactive_file:28kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15996kB managed:15912kB mlocked:0kB dirty:0kB writeback:0kB mapped:2676kB shmem:2664kB slab_reclaimable:44kB slab_unreclaimable:164kB kernel_stack:0kB pagetables:132kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:20 all_unreclaimable? no
Jun 19 03:06:07 panel kernel: lowmem_reserve[]: 0 1972 1972 1972
Jun 19 03:06:07 panel kernel: Node 0 DMA32 free:5736kB min:5656kB low:7068kB high:8484kB active_anon:1390704kB inactive_anon:463608kB active_file:1488kB inactive_file:1892kB unevictable:0kB isolated(anon):128kB isolated(file):0kB present:2080768kB managed:2023584kB mlocked:0kB dirty:0kB writeback:24kB mapped:675052kB shmem:673148kB slab_reclaimable:33312kB slab_unreclaimable:21984kB kernel_stack:4304kB pagetables:35416kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
Jun 19 03:06:07 panel kernel: lowmem_reserve[]: 0 0 0 0
Jun 19 03:06:07 panel kernel: Node 0 DMA: 4*4kB (UM) 5*8kB (U) 8*16kB (UM) 4*32kB (UM) 3*64kB (UE) 10*128kB (EM) 6*256kB (UEM) 1*512kB (U) 0*1024kB 0*2048kB 1*4096kB (R) = 7928kB
Jun 19 03:06:07 panel kernel: Node 0 DMA32: 97*4kB (UEMR) 10*8kB (MR) 0*16kB 0*32kB 1*64kB (R) 1*128kB (R) 0*256kB 0*512kB 1*1024kB (R) 0*2048kB 1*4096kB (R) = 5780kB
Jun 19 03:06:07 panel kernel: 174507 total pagecache pages
Jun 19 03:06:07 panel kernel: 4598 pages in swap cache
Jun 19 03:06:07 panel kernel: Swap cache stats: add 1673544, delete 1668946, find 6783627/7234079
Jun 19 03:06:07 panel kernel: Free swap = 0kB
Jun 19 03:06:07 panel kernel: Total swap = 262140kB
Jun 19 03:06:07 panel kernel: 524191 pages RAM
Jun 19 03:06:07 panel kernel: 0 pages HighMem/MovableOnly
Jun 19 03:06:07 panel kernel: 14317 pages reserved
Jun 19 03:06:07 panel kernel: [ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name
Jun 19 03:06:07 panel kernel: [ 1541] 0 1541 2710 0 9 2 127 -1000 udevd
Jun 19 03:06:07 panel kernel: [ 2129] 0 2129 2295 34 8 2 90 0 dhclient
Jun 19 03:06:07 panel kernel: [ 2175] 0 2175 6402 0 12 2 75 -1000 auditd
Jun 19 03:06:07 panel kernel: [ 2238] 0 2238 60749 0 21 3 214 0 rsyslogd
Jun 19 03:06:07 panel kernel: [ 2264] 25 2264 57836 0 44 2 4143 0 named
Jun 19 03:06:07 panel kernel: [ 2295] 81 2295 5373 0 14 2 63 0 dbus-daemon
Jun 19 03:06:07 panel kernel: [ 2350] 495 2350 80168 0 26 5 86 0 memcached
Jun 19 03:06:07 panel kernel: [ 2368] 0 2368 16569 11 34 2 166 -1000 sshd
Jun 19 03:06:07 panel kernel: [ 2662] 0 2662 4943 23 19 5 54 0 dovecot
Jun 19 03:06:07 panel kernel: [ 2665] 498 2665 10600 0 41 6 144 0 pop3-login
Jun 19 03:06:07 panel kernel: [ 2666] 498 2666 10639 0 41 6 153 0 imap-login
Jun 19 03:06:07 panel kernel: [ 2667] 97 2667 3369 0 18 5 49 0 anvil
Jun 19 03:06:07 panel kernel: [ 2668] 0 2668 3402 0 18 5 78 0 log
Jun 19 03:06:07 panel kernel: [ 2671] 498 2671 10636 18 41 6 120 0 pop3-login
Jun 19 03:06:07 panel kernel: [ 2672] 0 2672 4145 0 19 5 282 0 config
Jun 19 03:06:07 panel kernel: [ 2673] 498 2673 10635 0 42 6 145 0 imap-login
Jun 19 03:06:07 panel kernel: [ 2683] 47 2683 18053 15 49 7 136 0 exim
Jun 19 03:06:07 panel kernel: [ 2807] 0 2807 43014 217 108 6 12952 0 /usr/local/cpan
Jun 19 03:06:07 panel kernel: [ 2895] 0 2895 43249 4306 97 6 9070 0 spamd child
Jun 19 03:06:07 panel kernel: [ 2952] 501 2952 4042 0 14 4 33 0 newrelic-daemon
Jun 19 03:06:07 panel kernel: [ 2953] 0 2953 28675 0 16 2 52 0 abrtd
Jun 19 03:06:07 panel kernel: [ 2954] 501 2954 60989 123 29 4 544 0 newrelic-daemon
Jun 19 03:06:07 panel kernel: [ 2970] 0 2970 28181 0 23 4 65 0 abrt-dump-oops
Jun 19 03:06:07 panel kernel: [ 2981] 0 2981 34674 9 23 2 160 0 pure-ftpd
Jun 19 03:06:07 panel kernel: [ 2983] 0 2983 34047 7 27 2 114 0 pure-authd
Jun 19 03:06:07 panel kernel: [ 2995] 0 2995 29217 8 16 2 148 0 crond
Jun 19 03:06:07 panel kernel: [ 3009] 0 3009 5291 11 14 2 34 0 atd
Jun 19 03:06:07 panel kernel: [ 3521] 0 3521 35818 389 90 6 6493 0 cpsrvd (SSL) -
Jun 19 03:06:07 panel kernel: [ 3760] 0 3760 10172 158 34 4 1275 0 queueprocd - wa
Jun 19 03:06:07 panel kernel: [ 3832] 0 3832 28548 0 66 5 4769 0 dnsadmin - serv
Jun 19 03:06:07 panel kernel: [ 3858] 0 3858 21764 452 54 5 3245 0 tailwatchd
Jun 19 03:06:07 panel kernel: [ 3934] 0 3934 29015 2 65 5 5416 0 cpdavd - accept
Jun 19 03:06:07 panel kernel: [ 3964] 0 3964 7951 11 27 4 1315 0 cpanellogd - sl
Jun 19 03:06:07 panel kernel: [ 4002] 0 4002 1035 1 9 4 19 0 agetty
Jun 19 03:06:07 panel kernel: [ 4004] 0 4004 1031 0 9 4 17 0 mingetty
Jun 19 03:06:07 panel kernel: [ 4006] 0 4006 1031 0 9 4 18 0 mingetty
Jun 19 03:06:07 panel kernel: [ 4008] 0 4008 1031 0 9 4 18 0 mingetty
Jun 19 03:06:07 panel kernel: [ 4011] 0 4011 2709 0 9 2 128 -1000 udevd
Jun 19 03:06:07 panel kernel: [ 4012] 0 4012 2709 0 9 2 128 -1000 udevd
Jun 19 03:06:07 panel kernel: [ 4013] 0 4013 1031 0 9 4 18 0 mingetty
Jun 19 03:06:07 panel kernel: [ 4015] 0 4015 1031 0 9 4 18 0 mingetty
Jun 19 03:06:07 panel kernel: [ 4017] 0 4017 1031 0 8 4 17 0 mingetty
Jun 19 03:06:07 panel kernel: [16053] 0 16053 18080 444 59 5 138 0 httpd
Jun 19 03:06:07 panel kernel: [19702] 0 19702 2883 1 15 4 71 0 mysqld_safe
Jun 19 03:06:07 panel kernel: [19964] 497 19964 393396 49834 210 7 17743 0 mysqld
Jun 19 03:06:07 panel kernel: [22735] 0 22735 3368 26 17 5 0 0 ssl-params
Jun 19 03:06:07 panel kernel: [24373] 0 24373 20166 2064 63 5 9 0 leechprotect
Jun 19 03:06:07 panel kernel: [24374] 99 24374 18247 625 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24375] 99 24375 18259 641 48 5 127 0 httpd
Jun 19 03:06:07 panel kernel: [24378] 99 24378 18283 650 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24379] 99 24379 18207 582 48 5 131 0 httpd
Jun 19 03:06:07 panel kernel: [24380] 99 24380 18294 651 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24383] 99 24383 18251 632 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24388] 99 24388 18275 651 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24395] 99 24395 18232 610 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24438] 0 24438 4252 51 12 2 0 0 anacron
Jun 19 03:06:07 panel kernel: [24457] 99 24457 18249 629 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24460] 99 24460 18243 622 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24559] 99 24559 18234 611 48 5 129 0 httpd
Jun 19 03:06:07 panel kernel: [24688] 99 24688 18283 646 48 5 131 0 httpd
Jun 19 03:06:07 panel kernel: [24757] 97 24757 7930 113 30 5 0 0 auth
Jun 19 03:06:07 panel kernel: [24838] 507 24838 84744 21633 134 6 0 0 php
Jun 19 03:06:07 panel kernel: [24840] 507 24840 83776 20878 133 6 0 0 php
Jun 19 03:06:07 panel kernel: [24841] 507 24841 82483 18820 128 7 0 0 php
Jun 19 03:06:07 panel kernel: [24844] 507 24844 82937 20101 130 7 0 0 php
Jun 19 03:06:07 panel kernel: [24845] 507 24845 82227 18788 129 7 0 0 php
Jun 19 03:06:07 panel kernel: [24846] 507 24846 82291 19040 129 6 0 0 php
Jun 19 03:06:07 panel kernel: [24847] 507 24847 82887 19792 131 7 0 0 php
Jun 19 03:06:07 panel kernel: [24848] 507 24848 82934 20094 130 7 0 0 php
Jun 19 03:06:07 panel kernel: [24850] 507 24850 82894 19887 130 6 0 0 php
Jun 19 03:06:07 panel kernel: [24852] 507 24852 82548 19709 129 6 0 0 php
Jun 19 03:06:07 panel kernel: [24859] 507 24859 82803 19724 131 6 0 0 php
Jun 19 03:06:07 panel kernel: [24862] 99 24862 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24866] 507 24866 81465 17804 126 6 0 0 php
Jun 19 03:06:07 panel kernel: [24875] 99 24875 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24876] 99 24876 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24877] 507 24877 79415 14127 121 6 0 0 php
Jun 19 03:06:07 panel kernel: [24878] 507 24878 79221 13720 118 7 0 0 php
Jun 19 03:06:07 panel kernel: [24885] 99 24885 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24886] 99 24886 18182 523 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24887] 99 24887 18182 523 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24888] 99 24888 18182 523 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24892] 507 24892 77328 9824 111 6 0 0 php
Jun 19 03:06:07 panel kernel: [24898] 99 24898 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24899] 99 24899 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24900] 99 24900 18182 513 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24901] 99 24901 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24902] 99 24902 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24903] 99 24903 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24904] 99 24904 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24905] 99 24905 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24906] 507 24906 75260 6007 103 6 0 0 php
Jun 19 03:06:07 panel kernel: [24907] 507 24907 61544 14697 114 6 0 0 php
Jun 19 03:06:07 panel kernel: [24908] 507 24908 75724 6894 105 6 0 0 php
Jun 19 03:06:07 panel kernel: [24909] 507 24909 74348 5097 101 6 0 0 php
Jun 19 03:06:07 panel kernel: [24910] 507 24910 75746 6708 104 7 0 0 php
Jun 19 03:06:07 panel kernel: [24911] 507 24911 75746 6630 104 6 0 0 php
Jun 19 03:06:07 panel kernel: [24912] 507 24912 75746 6705 104 6 0 0 php
Jun 19 03:06:07 panel kernel: [24913] 507 24913 76743 8656 108 6 0 0 php
Jun 19 03:06:07 panel kernel: [24922] 507 24922 73138 3847 99 7 0 0 php
Jun 19 03:06:07 panel kernel: [24923] 507 24923 72900 3513 96 6 0 0 php
Jun 19 03:06:07 panel kernel: [24925] 507 24925 72704 3279 98 6 0 0 php
Jun 19 03:06:07 panel kernel: [24926] 507 24926 72856 3395 98 6 0 0 php
Jun 19 03:06:07 panel kernel: [24927] 99 24927 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24928] 99 24928 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24929] 99 24929 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24930] 99 24930 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24931] 99 24931 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24932] 99 24932 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24933] 99 24933 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24934] 99 24934 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24935] 99 24935 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24936] 507 24936 72900 3454 98 7 0 0 php
Jun 19 03:06:07 panel kernel: [24937] 507 24937 72900 3512 100 6 0 0 php
Jun 19 03:06:07 panel kernel: [24938] 507 24938 72898 3510 99 6 0 0 php
Jun 19 03:06:07 panel kernel: [24940] 99 24940 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24941] 99 24941 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24942] 99 24942 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24944] 507 24944 72709 3228 98 6 0 0 php
Jun 19 03:06:07 panel kernel: [24945] 507 24945 72707 3210 96 6 0 0 php
Jun 19 03:06:07 panel kernel: [24946] 507 24946 72505 2756 97 6 0 0 php
Jun 19 03:06:07 panel kernel: [24947] 507 24947 72770 3394 99 6 0 0 php
Jun 19 03:06:07 panel kernel: [24948] 507 24948 72898 3511 98 7 0 0 php
Jun 19 03:06:07 panel kernel: [24950] 507 24950 72920 3491 99 6 0 0 php
Jun 19 03:06:07 panel kernel: [24952] 99 24952 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24953] 99 24953 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24954] 99 24954 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24956] 507 24956 72273 2332 95 6 0 0 php
Jun 19 03:06:07 panel kernel: [24959] 507 24959 71635 1659 96 6 0 0 php
Jun 19 03:06:07 panel kernel: [24960] 507 24960 72358 2601 97 7 0 0 php
Jun 19 03:06:07 panel kernel: [24961] 507 24961 72431 2797 96 6 0 0 php
Jun 19 03:06:07 panel kernel: [24962] 507 24962 72565 2478 97 6 0 0 php
Jun 19 03:06:07 panel kernel: [24963] 99 24963 18149 480 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24964] 507 24964 72505 2727 98 6 0 0 php
Jun 19 03:06:07 panel kernel: [24965] 507 24965 71871 1883 95 6 0 0 php
Jun 19 03:06:07 panel kernel: [24987] 99 24987 18149 467 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24988] 99 24988 18149 472 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24989] 99 24989 18149 467 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24990] 99 24990 18149 479 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24991] 99 24991 18149 477 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24992] 507 24992 24451 62 72 6 0 0 php
Jun 19 03:06:07 panel kernel: [24993] 99 24993 18149 478 48 5 132 0 httpd
Jun 19 03:06:07 panel kernel: [24994] 99 24994 2998 13 14 4 0 0 suphp
Jun 19 03:06:07 panel kernel: [24995] 507 24995 5810 9 12 4 0 0 php
Jun 19 03:06:07 panel kernel: [24996] 507 24996 3880 9 10 4 0 0 php
Jun 19 03:06:07 panel kernel: [24998] 507 24998 6373 16 15 5 0 0 php
Jun 19 03:06:07 panel kernel: [24999] 507 24999 2767 1 3 3 0 0 php
Jun 19 03:06:07 panel kernel: [25000] 0 25000 18080 432 47 5 135 0 httpd
Jun 19 03:06:07 panel kernel: Out of memory: Kill process 19964 (mysqld) score 117 or sacrifice child
Jun 19 03:06:07 panel kernel: Killed process 19964 (mysqld) total-vm:1573584kB, anon-rss:199336kB, file-rss:0kB
Jun 19 03:06:07 panel kernel: php invoked oom-killer: gfp_mask=0x280da, order=0, oom_score_adj=0
Jun 19 03:06:07 panel kernel: php cpuset=/ mems_allowed=0
这是我的 Apache 设置：
Starts Servers 2
Minimum Spare Servers 6
Maximum Spare Servers 12
Server Limit 256
Max Clients 50
Max Requests Per Child 3000
Keep-Alive Off
Mysql my.cnf设置：
[mysqld]
innodb_file_per_table=1
open_files_limit=1024000
max_connections=75
key_buffer=32M
max_allowed_packet=268435456
thread_stack=128K
table_cache=32
innodb_buffer_pool_size=320M
default-storage-engine=MyISAM
query_cache_size=8M
tmp_table_size=16M
max_heap_table_size=16M
thread_cache_size=4
table_open_cache=32
请帮忙，我已尽力追踪此事，但仍无法真正找出原因。
顺便说一下一些额外的随机花絮：
-我的网站上的某些页面有很多图片（超过 100 张），不确定这些是否算作额外的客户端/请求并以某种方式影响性能。
-我的 Wordpress 内存限制设置在 400MB 左右。
-该网站的 Mysql 数据库约为 175MB。其中 91MB 来自 WP_Options。
-Mysqltuner.pl 一直告诉我增加 tmp_table_size 和 max_heap_table_size，即使我已经将它们设置为 200M！
-这是我现在的 htop 截图。似乎 mysql 一直在使用 40% 的内存，并且由于某种原因，交换内存几乎已满。这是正常的吗？：
更新：我已将最大客户端数降低到 35，但仍然出现一些奇怪的 mysql 崩溃。Newrelic 错误消息是未知存储引擎“InnoDB”（我的 mysqltuner.pl 说 InnoDB 已禁用，但它是默认存储引擎）。我的网站告诉我重新安装 Wordpress，就像全新安装一样，我必须重新启动 mysql 或服务器才能解决此问题。
答案1
并发用户数通常在 10 个左右，不会超过 20 个
...但是您的屏幕截图显示有 23 个活动的 mysql 会话，而您将 Web 服务器配置为允许 256 个。
廉价托管上的交换是一种反模式 - 一旦您的机器开始进入交换，它将花费所有时间读取和写入交换文件，而请求开始在 Apache 上备份。
我对 Wordpress 没什么好说的。
我从您的屏幕截图中看到 PHP 的 CLI SAPI 正在运行。并且 oom killer 认为 PHP 是系统内存占用最大的罪魁祸首。这表明您正在运行 CGI PHP，而不是 mod_php 或 php-fpm。如果是这样，那么我们不仅解决了您的主机内存不足的问题，还解决了您的页面速度如此缓慢的问题，
保持活动关闭
这真的没什么帮助。这肯定会让浏览器端的体验变得更糟。即使你已经配置了缓存和 CDN，也应该将超时时间设置为低于 500 毫秒确切地正确的。
这显然不是您的 Apache 配置的全部内容 - 并且许多其他设置也很重要。确保启用压缩是一个重要设置（压缩数据比处理 TCP 流量占用的 CPU 时间更少，并且意味着您没有大型 Apache 进程在内存中等待数据传输）。
尽管你提供了大量关于发生的事情的信息后oom killer 需要查看在此之前发生了什么。默认情况下不会捕获这些信息。最低限度是跟踪内存使用量与 Apache 实例数量。
答案2
由于某种原因，您遇到了 maxclients 参数。
关于服务器宕机时每秒请求量，您还有什么信息吗？看起来您的交换空间已完全填满，导致服务器崩溃。您有关于哪些组件使用了多少内存的信息吗？
答案3
检查服务器内存使用情况的一个简单方法是安装一个名为 的工具htop。htop 将为您提供每个进程的服务器重要信息。如果您想检查内存，可以加载 htop 并按“M内存”排序（或>选择一个类别）。
一旦找出哪个应用程序占用的内存最多（我猜是 Apache，考虑到您同时达到最大客户端数并触发 OOM 终止程序），您就可以对其进行微调。不过，我并不怀疑您这里存在容量问题。如您的日志所示，您已达到 Apache 的最大客户端数，但您现在无法安全地增加该值，因为您不确定 RAM 的大小。这会影响您的客户。获取一套好的监控工具并随时掌握它。
此外，在崩溃时检查一下 Apache 访问日志也没什么坏处。您说通常不会有超过 20 个并发用户，但您已经达到了 50 个 Apache 进程的最大限制。如果这是合法流量，那么您需要更好地调整服务器并可能升级资源。如果不是，那么也许可以尝试找到一种方法来过滤垃圾（说起来容易做起来难）。