博客在今天凌晨 0:43 再一次 502 了，为什么是再一次？因为这种情况出现了几次。虽然知道是 php-fpm 服务被 OOM 了，但没有考虑太多，直接 systemctl restart php-fpm 了事，恰逢是周六，花点时间来研究一下为什么默认配置情况下出现多次的 OOM。
首先不得不承认 OOM 出现的原因就是内存不足，解决 OOM 的办法就是增加内存，但当前使用的 VPS 拥有 2GB 的内存，这对于运行一个访问量非常低（几乎没有）的博客来说是很大的了，更别说最早还用过 32MB 的 VPS 运行 Typecho 呢。同时后续打算迁移到更具性价比的 512MB 内存的 VPS 上，毕竟没有什么负载，所以我这次不得不面对这个问题。
PHP-FPM 首先需要搞清楚运行的 php-fpm.service 是个什么东西。php-fpm 。
以前的 CGI 程序每当收到 Web 服务器的请求后，会读取 PHP 的配置，初始化环境，然后解析 PHP 脚本并返回结果，最后退出程序。每一个请求过来都需要重复这个操作，效率比较低。因此 php-fastcgi 带来了改变。
php-fastcgi 启动时会读取一次 PHP 配置文件，然后产生一个 master 进程和多个 worker 进程。当收到请求时，master 会将请求转发给一个 worker，当有多个请求的时候，master 会转发给底下的多个 worker，当 worker 不够的时候，master 会根据配置文件动态的创建 worker 进程，所以接受请求的时候不会受到阻塞，这非常类似于 Nginx ，当然也会根据配置来销毁空闲 worker 进程。 php-fpm.service 就是用来管理 php-fastcgi 的 master 和 worker 进程。
分析日志 知道了 php-fpm 之后，可以得到其实解析 PHP 脚本的进程是 worker 进程，那么可以通过查看 OOM 时的日志，找到当时 worker 进程的状况。
博客是在 00:43 挂的，所以使用 journalctl 命令查询特定时间段的日志：
1 [root@sz-blog ~]# journalctl --since 00:40 --until 00:43 > /tmp/oom.log
日志内容如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 Nov 25 00:43:01 kernel: tuned invoked oom-killer: gfp_mask=0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), order=0, oom_score_adj=0 Nov 25 00:43:02 kernel: CPU: 0 PID: 678 Comm: tuned Not tainted 5.14.0-368.el9.x86_64 #1 Nov 25 00:43:02 kernel: Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 449e491 04/01/2014 Nov 25 00:43:02 kernel: Call Trace: Nov 25 00:43:02 kernel: <TASK> Nov 25 00:43:02 kernel: dump_stack_lvl+0x34/0x48 Nov 25 00:43:02 kernel: dump_header+0x4a/0x201 Nov 25 00:43:02 kernel: oom_kill_process.cold+0xb/0x10 Nov 25 00:43:02 kernel: out_of_memory+0xed/0x2e0 Nov 25 00:43:02 kernel: __alloc_pages_slowpath.constprop.0+0x6e8/0x960 Nov 25 00:43:02 kernel: __alloc_pages+0x21d/0x250 Nov 25 00:43:02 kernel: folio_alloc+0x17/0x50 Nov 25 00:43:02 kernel: __filemap_get_folio+0x1cd/0x330 Nov 25 00:43:02 kernel: filemap_fault+0x40b/0x740 Nov 25 00:43:02 kernel: __do_fault+0x36/0x140 Nov 25 00:43:02 kernel: do_read_fault+0xf0/0x160 Nov 25 00:43:02 kernel: do_fault+0xa9/0x390 Nov 25 00:43:03 kernel: __handle_mm_fault+0x585/0x650 Nov 25 00:43:03 kernel: handle_mm_fault+0xc5/0x2a0 Nov 25 00:43:03 kernel: do_user_addr_fault+0x1b4/0x6a0 Nov 25 00:43:03 kernel: exc_page_fault+0x62/0x150 Nov 25 00:43:03 kernel: asm_exc_page_fault+0x22/0x30 Nov 25 00:43:03 kernel: RIP: 0033:0x7f949189c39a Nov 25 00:43:03 kernel: Code: Unable to access opcode bytes at RIP 0x7f949189c370. Nov 25 00:43:03 kernel: RSP: 002b:00007ffdd43d21f0 EFLAGS: 00010246 Nov 25 00:43:03 kernel: RAX: ffffffffffffff92 RBX: 00007ffdd43d2330 RCX: 00007f949189c39a Nov 25 00:43:03 kernel: RDX: 0000000000000000 RSI: 0000000000000089 RDI: 00007f9491f40fec Nov 25 00:43:03 kernel: RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000ffffffff Nov 25 00:43:03 kernel: R10: 00007ffdd43d2330 R11: 0000000000000246 R12: 0000000000000000 Nov 25 00:43:03 kernel: R13: 00007f9491f40fec R14: 0000000000000000 R15: 00007f9491f40ff0 Nov 25 00:43:03 kernel: </TASK> Nov 25 00:43:03 kernel: Mem-Info: Nov 25 00:43:03 kernel: active_anon:30750 inactive_anon:358463 isolated_anon:0 active_file:7 inactive_file:8378 isolated_file:0 unevictable:0 dirty:0 writeback:0 slab_reclaimable:10254 slab_unreclaimable:14247 mapped:33452 shmem:33896 pagetables:6074 sec_pagetables:0 bounce:0 kernel_misc_reclaimable:0 free:13407 free_pcp:62 free_cma:0 Nov 25 00:43:03 kernel: Node 0 active_anon:123000kB inactive_anon:1433852kB active_file:28kB inactive_file:33512kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:133808kB dirty:0kB writeback:0kB shmem:135584kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 751616kB writeback_tmp:0kB kernel_stack:4368kB pagetables:24296kB sec_pagetables:0kB all_unreclaimable? yes Nov 25 00:43:03 kernel: Node 0 DMA free:7252kB boost:0kB min:388kB low:484kB high:580kB reserved_highatomic:0KB active_anon:180kB inactive_anon:5704kB active_file:0kB inactive_file:104kB unevictable:0kB writepending:0kB present:15992kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB Nov 25 00:43:03 kernel: lowmem_reserve[]: 0 1710 1710 1710 1710 Nov 25 00:43:03 kernel: Node 0 DMA32 free:46376kB boost:0kB min:44664kB low:55828kB high:66992kB reserved_highatomic:0KB active_anon:122820kB inactive_anon:1428148kB active_file:136kB inactive_file:33440kB unevictable:0kB writepending:0kB present:2080640kB managed:1790624kB mlocked:0kB bounce:0kB free_pcp:248kB local_pcp:0kB free_cma:0kB Nov 25 00:43:03 kernel: lowmem_reserve[]: 0 0 0 0 0 Nov 25 00:43:03 kernel: Node 0 DMA: 47*4kB (UME) 12*8kB (UME) 12*16kB (UE) 22*32kB (UME) 11*64kB (UME) 10*128kB (UME) 2*256kB (UM) 3*512kB (UME) 2*1024kB (UM) 0*2048kB 0*4096kB = 7260kB Nov 25 00:43:03 kernel: Node 0 DMA32: 324*4kB (UME) 354*8kB (UME) 260*16kB (UME) 361*32kB (UME) 182*64kB (ME) 67*128kB (UME) 25*256kB (UM) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 46464kB Nov 25 00:43:03 kernel: Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB Nov 25 00:43:03 kernel: Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB Nov 25 00:43:03 kernel: 42295 total pagecache pages Nov 25 00:43:03 kernel: 0 pages in swap cache Nov 25 00:43:03 kernel: Free swap = 0kB Nov 25 00:43:03 kernel: Total swap = 0kB Nov 25 00:43:03 kernel: 524158 pages RAM Nov 25 00:43:03 kernel: 0 pages HighMem/MovableOnly Nov 25 00:43:03 kernel: 72662 pages reserved Nov 25 00:43:03 kernel: 0 pages cma reserved Nov 25 00:43:03 kernel: 0 pages hwpoisoned Nov 25 00:43:03 kernel: Tasks state (memory values in pages): Nov 25 00:43:03 kernel: [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name Nov 25 00:43:03 kernel: [ 460] 0 460 8620 329 94208 0 -250 systemd-journal Nov 25 00:43:03 kernel: [ 473] 0 473 8085 497 90112 0 -1000 systemd-udevd Nov 25 00:43:03 kernel: [ 553] 81 553 2723 199 57344 0 -900 dbus-broker-lau Nov 25 00:43:03 kernel: [ 554] 81 554 1314 159 49152 0 -900 dbus-broker Nov 25 00:43:03 kernel: [ 556] 0 556 139890 2139 147456 0 0 CmsGoAgent.linu Nov 25 00:43:03 kernel: [ 560] 997 560 676 40 40960 0 0 lsmd Nov 25 00:43:03 kernel: [ 561] 0 561 4641 286 77824 0 0 systemd-logind Nov 25 00:43:04 kernel: [ 573] 991 573 21130 184 65536 0 0 chronyd Nov 25 00:43:04 kernel: [ 596] 0 596 250781 4912 217088 0 0 exe Nov 25 00:43:04 kernel: [ 641] 0 641 64282 1178 139264 0 0 NetworkManager Nov 25 00:43:04 kernel: [ 675] 982 675 112209 9776 196608 0 0 memcached Nov 25 00:43:04 kernel: [ 677] 0 677 71269 2871 249856 0 0 php-fpm Nov 25 00:43:04 kernel: [ 678] 0 678 64074 3261 131072 0 0 tuned Nov 25 00:43:04 kernel: [ 848] 27 848 390742 30204 471040 0 0 mariadbd Nov 25 00:43:04 kernel: [ 871] 998 871 627854 1566 196608 0 0 polkitd Nov 25 00:43:04 kernel: [ 956] 0 956 3948 322 69632 0 -1000 sshd Nov 25 00:43:04 kernel: [ 959] 0 959 2137 215 49152 0 0 crond Nov 25 00:43:04 kernel: [ 960] 0 960 761 23 49152 0 0 agetty Nov 25 00:43:04 kernel: [ 961] 0 961 1403 22 53248 0 0 agetty Nov 25 00:43:04 kernel: [ 998] 0 998 6151 650 69632 0 0 nginx Nov 25 00:43:04 kernel: [ 10420] 983 10420 14003 8925 143360 0 0 nginx Nov 25 00:43:04 kernel: [ 10421] 983 10421 14217 9115 143360 0 0 nginx Nov 25 00:43:04 kernel: [ 13948] 983 13948 107522 39919 634880 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13951] 983 13951 107900 40635 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13952] 983 13952 108157 41937 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13953] 983 13953 107539 40598 634880 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13954] 983 13954 108054 40737 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 77409] 0 77409 203988 1105 86016 0 0 aliyun-service Nov 25 00:43:04 kernel: [ 77562] 0 77562 4857 243 65536 0 0 assist_daemon Nov 25 00:43:04 kernel: [ 82166] 983 82166 107787 35231 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82168] 983 82168 107819 35405 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82169] 983 82169 110583 39080 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82172] 983 82172 107824 35183 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82173] 983 82173 107215 35214 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82174] 983 82174 107278 34634 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82175] 983 82175 107223 33393 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82180] 983 82180 107317 35138 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82181] 983 82181 107777 34662 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82182] 983 82182 107249 35199 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82183] 983 82183 110966 38218 643072 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82184] 983 82184 107787 35609 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82190] 983 82190 107309 34645 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82191] 983 82191 107753 34230 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82192] 983 82192 107301 35175 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82193] 983 82193 107762 34650 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82194] 983 82194 107357 35015 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82200] 983 82200 106742 34020 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82201] 983 82201 107737 35328 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82202] 983 82202 107819 34901 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82203] 983 82203 107752 35727 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82204] 983 82204 107264 35391 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82210] 983 82210 107308 33879 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82211] 983 82211 107318 34622 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82212] 983 82212 107744 35832 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82213] 983 82213 107251 35344 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82214] 983 82214 107813 34812 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82220] 983 82220 107235 34438 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82221] 983 82221 107304 34841 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82222] 983 82222 107816 36233 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 88622] 0 88622 10741 975 94208 0 0 AliYunDunUpdate Nov 25 00:43:04 kernel: [ 88653] 0 88653 26767 2245 282624 0 0 AliYunDun Nov 25 00:43:04 kernel: [ 88664] 0 88664 46790 4263 393216 0 0 AliYunDunMonito Nov 25 00:43:04 kernel: oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/system.slice/php-fpm.service,task=php-fpm,pid=13952,uid=983 Nov 25 00:43:04 kernel: Out of memory: Killed process 13952 (php-fpm) total-vm:432628kB, anon-rss:38968kB, file-rss:0kB, shmem-rss:128780kB, UID:983 pgtables:624kB oom_score_adj:0 Nov 25 00:43:05 systemd[1]: php-fpm.service: A process of this unit has been killed by the OOM killer. Nov 25 00:43:06 systemd[1]: php-fpm.service: Failed with result 'oom-kill'. Nov 25 00:43:06 systemd[1]: php-fpm.service: Consumed 2h 33min 29.899s CPU time.
可以看到当系统内存不足的时候，php-fpm 由于占用内存最多且没有设置 oom_score_adj 导致被杀掉。php-fpm 的 error.log 也可以看到是被 SIGKILL 信号干掉的：
1 2 3 4 5 6 [root@sz-blog ~]# cat /var/log/php-fpm/error.log [19-Nov-2023 00:00:05] NOTICE: error log file re-opened [25-Nov-2023 00:43:01] WARNING: [pool www] child 13952 exited on signal 9 (SIGKILL) after 4019353.418821 seconds from start [25-Nov-2023 00:43:01] NOTICE: [pool www] child 95930 started [25-Nov-2023 00:43:05] NOTICE: Terminating ... [25-Nov-2023 00:43:05] NOTICE: exiting, bye-bye!
把日志稍微处理以下，看一下当时 php-fpm 服务管理的进程信息：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 [root@sz-blog ~]# grep php-fpm$ /tmp/oom.log Nov 25 00:43:04 kernel: [ 677] 0 677 71269 2871 249856 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13948] 983 13948 107522 39919 634880 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13951] 983 13951 107900 40635 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13952] 983 13952 108157 41937 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13953] 983 13953 107539 40598 634880 0 0 php-fpm Nov 25 00:43:04 kernel: [ 13954] 983 13954 108054 40737 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82166] 983 82166 107787 35231 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82168] 983 82168 107819 35405 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82169] 983 82169 110583 39080 638976 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82172] 983 82172 107824 35183 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82173] 983 82173 107215 35214 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82174] 983 82174 107278 34634 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82175] 983 82175 107223 33393 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82180] 983 82180 107317 35138 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82181] 983 82181 107777 34662 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82182] 983 82182 107249 35199 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82183] 983 82183 110966 38218 643072 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82184] 983 82184 107787 35609 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82190] 983 82190 107309 34645 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82191] 983 82191 107753 34230 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82192] 983 82192 107301 35175 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82193] 983 82193 107762 34650 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82194] 983 82194 107357 35015 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82200] 983 82200 106742 34020 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82201] 983 82201 107737 35328 622592 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82202] 983 82202 107819 34901 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82203] 983 82203 107752 35727 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82204] 983 82204 107264 35391 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82210] 983 82210 107308 33879 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82211] 983 82211 107318 34622 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82212] 983 82212 107744 35832 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82213] 983 82213 107251 35344 614400 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82214] 983 82214 107813 34812 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82220] 983 82220 107235 34438 610304 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82221] 983 82221 107304 34841 618496 0 0 php-fpm Nov 25 00:43:04 kernel: [ 82222] 983 82222 107816 36233 622592 0 0 php-fpm
除去一个 master 进程外，足足有 35 个 worker ，每个 worker 占用的 rss 也很大，问题就是出现在这里了。我需要这么多个 worker 进程吗？
配置 php-fpm php-fpm 提供了一个默认的配置文件，位于 /etc/php-fpm.d/www.conf，在这个配置文件中，有描述了 worker 进程数量相关的配置：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 ; Choose how the process manager will control the number of child processes. ; Possible Values: ; static - a fixed number (pm.max_children) of child processes; ; dynamic - the number of child processes are set dynamically based on the ; following directives. With this process management, there will be ; always at least 1 children. ; pm.max_children - the maximum number of children that can ; be alive at the same time. ; pm.start_servers - the number of children created on startup. ; pm.min_spare_servers - the minimum number of children in 'idle' ; state (waiting to process). If the number ; of 'idle' processes is less than this ; number then some children will be created. ; pm.max_spare_servers - the maximum number of children in 'idle' ; state (waiting to process). If the number ; of 'idle' processes is greater than this ; number then some children will be killed. ; ondemand - no children are created at startup. Children will be forked when ; new requests will connect. The following parameter are used: ; pm.max_children - the maximum number of children that ; can be alive at the same time. ; pm.process_idle_timeout - The number of seconds after which ; an idle process will be killed. ; Note: This value is mandatory. pm = dynamic
选择管理进程数量的类型有三种：
static 静态的指定进程数量
dynamic 基于一些配置动态的管理进程数量
ondemand 启动时不创建子进程，当新请求进来时再创建，这种类型已被废弃，不考虑
static static 模式下只需要配置 pm.max_children 就可以了，可以根据系统内存容量进行计算。
dynamic dynamic 模式下进程数最少为 1 个，且通过以下参数进行调整数量：
pm.max_children 定义进程最多的数目
pm.start_servers 启动时创建进程的数目
pm.min_spare_servers 最小处于 idle 状态的进程数量，少于的话将会创建
pm.max_spare_servers 最大处于 idle 状态的进程数量，大于的话将会被销毁
计算合理的进程数目 列出所有的 php-fpm 进程：
1 2 3 4 5 6 7 8 9 [root@sz-blog ~]# ps -ylC php-fpm --sort:rss S UID PID PPID C PRI NI RSS SZ WCHAN TTY TIME CMD S 0 96826 1 0 80 0 38412 71269 ep_pol ? 00:00:00 php-fpm S 983 96828 96826 0 80 0 99464 75530 skb_wa ? 00:00:06 php-fpm S 983 96835 96826 0 80 0 106412 94747 skb_wa ? 00:00:06 php-fpm S 983 96831 96826 0 80 0 106920 95270 skb_wa ? 00:00:06 php-fpm S 983 96832 96826 0 80 0 107080 94756 skb_wa ? 00:00:06 php-fpm S 983 96829 96826 0 80 0 107208 94781 skb_wa ? 00:00:06 php-fpm S 983 96830 96826 0 80 0 127036 106533 skb_wa ? 00:00:06 php-fpm
计算平均值：
1 2 [root@sz-blog ~]# ps --no-headers -o "rss,cmd" -C php-fpm | awk '{ sum+=$1 } END { printf ("%d%s\n", sum/NR/1024,"M") }' 96M
可得出每个 Pool 平均使用的内存大概为 96M，由此可以计算系统最多能创建多少个进程，计算公式：最大数量=可用内存/平均使用内存10 。static 模式的话，pm.max_children 设置为 10，如果设置为 dynamic ，则相关参数可参考：
1 2 3 4 pm.max_children = 10 pm.start_servers = 2 pm.min_spare_servers = 1 pm.max_spare_servers = 5
应用配置并检查状态 修改完成后需要重启 php-fpm，并验证相关值：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 [root@sz-blog ~]# systemctl restart php-fpm.service [root@sz-blog ~]# systemctl status php-fpm.service ● php-fpm.service - The PHP FastCGI Process Manager Loaded: loaded (/usr/lib/systemd/system/php-fpm.service; enabled; preset: disabled) Active: active (running) since Sat 2023-11-25 13:33:20 CST; 3s ago Main PID: 97658 (php-fpm) Status: "Ready to handle connections" Tasks: 3 (limit: 11041) Memory: 19.4M CPU: 71ms CGroup: /system.slice/php-fpm.service ├─97658 "php-fpm: master process (/etc/php-fpm.conf)" ├─97659 "php-fpm: pool www" └─97660 "php-fpm: pool www" Nov 25 13:33:20 sz-blog systemd[1]: Starting The PHP FastCGI Process Manager... Nov 25 13:33:20 sz-blog systemd[1]: Started The PHP FastCGI Process Manager.
可以看到启动后只有两个 worker 进程，后续需要注意内存使用量和进程的数量。
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