MySql 随机崩溃内存不足：杀死进程 24978 (mysqld) 得分 99 或牺牲子进程

Question

我正在运行 LEMP 服务器。Hetzner Cloud 上的 2Core 处理器、4GB RAM。Ubuntu 18.04、PHP7.4、MySql 5.7、Nginx 1.16

但是我的 MySql 服务器即使流量很小也会随机崩溃。一个月内会发生 2-3 次。

如何防止将来再次出现此问题？

这是来自 journalctl -xe 的日志

看到第一行，它说：11 月 23 日 03:48:49 ubuntu-server-18 内核：php-fpm7.4 调用 oom-killer：gfp_mask=0x14200ca(GFP_HIGHUSER_MOVABLE)，nodemask=(null)，order=0，oom_score_adj=0

问题是否由 php-fpm 引起？

=============

Nov 23 03:48:49 ubuntu-server-18 kernel: php-fpm7.4 invoked oom-killer: gfp_mask=0x14200ca(GFP_HIGHUSER_MOVABLE), nodemask=(null), order=0, oom_score_adj=0
Nov 23 03:48:50 ubuntu-server-18 kernel: php-fpm7.4 cpuset=/ mems_allowed=0
Nov 23 03:48:50 ubuntu-server-18 kernel: CPU: 0 PID: 24811 Comm: php-fpm7.4 Not tainted 4.15.0-64-generic #73-Ubuntu
Nov 23 03:48:50 ubuntu-server-18 kernel: Hardware name: Hetzner vServer, BIOS 20171111 11/11/2017
Nov 23 03:48:50 ubuntu-server-18 kernel: Call Trace:
Nov 23 03:48:50 ubuntu-server-18 kernel:  dump_stack+0x63/0x8b
Nov 23 03:48:50 ubuntu-server-18 kernel:  dump_header+0x71/0x285
Nov 23 03:48:50 ubuntu-server-18 kernel:  ? security_capable_noaudit+0x4b/0x70
Nov 23 03:48:50 ubuntu-server-18 kernel:  oom_kill_process+0x21f/0x420
Nov 23 03:48:50 ubuntu-server-18 kernel:  out_of_memory+0x2b6/0x4d0
Nov 23 03:48:50 ubuntu-server-18 kernel:  __alloc_pages_slowpath+0xa53/0xe00
Nov 23 03:48:50 ubuntu-server-18 kernel:  __alloc_pages_nodemask+0x29a/0x2c0
Nov 23 03:48:50 ubuntu-server-18 kernel:  alloc_pages_current+0x6a/0xe0
Nov 23 03:48:50 ubuntu-server-18 kernel:  __page_cache_alloc+0x81/0xa0
Nov 23 03:48:50 ubuntu-server-18 kernel:  filemap_fault+0x3ea/0x6f0
Nov 23 03:48:50 ubuntu-server-18 kernel:  ? page_add_file_rmap+0x134/0x180
Nov 23 03:48:50 ubuntu-server-18 kernel:  ? filemap_map_pages+0x22c/0x390
Nov 23 03:48:50 ubuntu-server-18 kernel:  ext4_filemap_fault+0x31/0x44
Nov 23 03:48:50 ubuntu-server-18 kernel:  __do_fault+0x5b/0x115
Nov 23 03:48:50 ubuntu-server-18 kernel:  __handle_mm_fault+0xdef/0x1290
Nov 23 03:48:50 ubuntu-server-18 kernel:  handle_mm_fault+0xb1/0x210
Nov 23 03:48:50 ubuntu-server-18 kernel:  __do_page_fault+0x281/0x4b0
Nov 23 03:48:50 ubuntu-server-18 kernel:  do_page_fault+0x2e/0xe0
Nov 23 03:48:50 ubuntu-server-18 kernel:  ? async_page_fault+0x2f/0x50
Nov 23 03:48:50 ubuntu-server-18 kernel:  do_async_page_fault+0x51/0x80
Nov 23 03:48:50 ubuntu-server-18 kernel:  async_page_fault+0x45/0x50
Nov 23 03:48:50 ubuntu-server-18 kernel: RIP: 0033:0x7f3be729d140
Nov 23 03:48:50 ubuntu-server-18 kernel: RSP: 002b:00007fff1d94b888 EFLAGS: 00010206
Nov 23 03:48:50 ubuntu-server-18 kernel: RAX: 0000000000000042 RBX: 0000000000000043 RCX: 0000000000000000
Nov 23 03:48:50 ubuntu-server-18 kernel: RDX: 00007f3bcdd5c400 RSI: 0000000036393034 RDI: 0000000000000043
Nov 23 03:48:50 ubuntu-server-18 kernel: RBP: 00007f3bcdd5c400 R08: 00007fff1d94b820 R09: 0000000000000036
Nov 23 03:48:50 ubuntu-server-18 kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 000055f7b0be96a0
Nov 23 03:48:50 ubuntu-server-18 kernel: R13: 0000000000000200 R14: 0000000000000001 R15: 00007f3bcdd5c400
Nov 23 03:48:50 ubuntu-server-18 kernel: Mem-Info:
Nov 23 03:48:50 ubuntu-server-18 kernel: active_anon:915548 inactive_anon:1944 isolated_anon:0
                                          active_file:97 inactive_file:107 isolated_file:1
                                          unevictable:0 dirty:5 writeback:0 unstable:0
                                          slab_reclaimable:7073 slab_unreclaimable:18771
                                          mapped:37449 shmem:47203 pagetables:11749 bounce:0
                                          free:21461 free_pcp:471 free_cma:0
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 active_anon:3662192kB inactive_anon:7776kB active_file:388kB inactive_file:428kB unevictable:0kB isolated(anon):0kB isolated(file):4kB mapped:149796kB dirty:20kB writeback:0kB shmem:188812kB
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 DMA free:15472kB min:272kB low:340kB high:408kB active_anon:380kB inactive_anon:0kB active_file:4kB inactive_file:8kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked
Nov 23 03:48:50 ubuntu-server-18 kernel: lowmem_reserve[]: 0 2968 3803 3803 3803
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 DMA32 free:55640kB min:52528kB low:65660kB high:78792kB active_anon:2931328kB inactive_anon:448kB active_file:732kB inactive_file:696kB unevictable:0kB writepending:0kB present:3129204kB man
Nov 23 03:48:50 ubuntu-server-18 kernel: lowmem_reserve[]: 0 0 835 835 835
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 Normal free:14732kB min:14776kB low:18468kB high:22160kB active_anon:729848kB inactive_anon:7328kB active_file:564kB inactive_file:28kB unevictable:0kB writepending:136kB present:950272kB ma
Nov 23 03:48:50 ubuntu-server-18 kernel: lowmem_reserve[]: 0 0 0 0 0
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 DMA: 3*4kB (UM) 1*8kB (U) 2*16kB (UM) 0*32kB 3*64kB (UM) 1*128kB (U) 1*256kB (U) 1*512kB (M) 2*1024kB (UM) 0*2048kB 3*4096kB (ME) = 15476kB
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 DMA32: 436*4kB (UEH) 565*8kB (EH) 582*16kB (UEH) 386*32kB (EH) 191*64kB (UME) 63*128kB (UMEH) 15*256kB (ME) 1*512kB (M) 1*1024kB (U) 1*2048kB (U) 0*4096kB = 55640kB
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 Normal: 529*4kB (UMEH) 217*8kB (UMEH) 123*16kB (UEH) 96*32kB (UMEH) 23*64kB (UEH) 6*128kB (UMH) 6*256kB (MH) 1*512kB (M) 2*1024kB (MH) 0*2048kB 0*4096kB = 15228kB
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
Nov 23 03:48:50 ubuntu-server-18 kernel: Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
Nov 23 03:48:50 ubuntu-server-18 kernel: 47438 total pagecache pages
Nov 23 03:48:50 ubuntu-server-18 kernel: 0 pages in swap cache
Nov 23 03:48:50 ubuntu-server-18 kernel: Swap cache stats: add 0, delete 0, find 0/0
Nov 23 03:48:50 ubuntu-server-18 kernel: Free swap  = 0kB
Nov 23 03:48:50 ubuntu-server-18 kernel: Total swap = 0kB
Nov 23 03:48:50 ubuntu-server-18 kernel: 1023867 pages RAM
Nov 23 03:48:50 ubuntu-server-18 kernel: 0 pages HighMem/MovableOnly
Nov 23 03:48:50 ubuntu-server-18 kernel: 38546 pages reserved
Nov 23 03:48:50 ubuntu-server-18 kernel: 0 pages cma reserved
Nov 23 03:48:50 ubuntu-server-18 kernel: 0 pages hwpoisoned
Nov 23 03:48:50 ubuntu-server-18 kernel: [ pid ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name
Nov 23 03:48:50 ubuntu-server-18 kernel: [  448]     0   448    26475       46    94208        0             0 lvmetad
Nov 23 03:48:50 ubuntu-server-18 kernel: [  846]     0   846     6499      317    86016        0             0 dhclient
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1080]     0  1080   206132      332   163840        0             0 lxcfs
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1082]   102  1082    65759      366   167936        0             0 rsyslogd
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1084]     0  1084    17682      222   180224        0             0 systemd-logind
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1086]     0  1086     7506       72   106496        0             0 cron
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1087]     0  1087    27619       89   122880        0             0 irqbalance
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1088]     0  1088    42284     1945   221184        0             0 networkd-dispat
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1105]   103  1105    12574      230   139264        0          -900 dbus-daemon
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1126]     0  1126     7082       53    98304        0             0 atd
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1132]     0  1132    18075      187   188416        0         -1000 sshd
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1142]     0  1142    72220      230   200704        0             0 polkitd
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1143]     0  1143     3666       35    69632        0             0 agetty
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1145]     0  1145     3722       32    73728        0             0 agetty
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1158]     0  1158    46486     1977   262144        0             0 unattended-upgr
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1159]     0  1159     5764       56    86016        0             0 qemu-ga
Nov 23 03:48:50 ubuntu-server-18 kernel: [ 1228]     0  1228    43539     3614   237568        0             0 nginx
Nov 23 03:48:50 ubuntu-server-18 kernel: [25966]   101 25966    17730      228   180224        0             0 systemd-resolve
Nov 23 03:48:50 ubuntu-server-18 kernel: [25996] 62583 25996    35489      151   176128        0             0 systemd-timesyn
Nov 23 03:48:50 ubuntu-server-18 kernel: [26018]     0 26018    30318      708   249856        0             0 systemd-journal
Nov 23 03:48:50 ubuntu-server-18 kernel: [16675]     0 16675    10731      184   118784        0         -1000 systemd-udevd
Nov 23 03:48:50 ubuntu-server-18 kernel: [19523]     0 19523    71587      280   188416        0             0 accounts-daemon
Nov 23 03:48:50 ubuntu-server-18 kernel: [30852]     0 30852   235988     4258   274432        0          -900 snapd
Nov 23 03:48:50 ubuntu-server-18 kernel: [14252]     0 14252    72771     2616   425984        0             0 php-fpm5.6
Nov 23 03:48:50 ubuntu-server-18 kernel: [14272]    33 14272    73345     1286   405504        0             0 php-fpm5.6
Nov 23 03:48:50 ubuntu-server-18 kernel: [14274]    33 14274    73345     1286   405504        0             0 php-fpm5.6
Nov 23 03:48:50 ubuntu-server-18 kernel: [14319]     0 14319   112080     1758   581632        0             0 php-fpm7.2
Nov 23 03:48:50 ubuntu-server-18 kernel: [14341]    33 14341   112654     1367   552960        0             0 php-fpm7.2
Nov 23 03:48:50 ubuntu-server-18 kernel: [14345]    33 14345   112654     1367   552960        0             0 php-fpm7.2
Nov 23 03:48:50 ubuntu-server-18 kernel: [31607]     0 31607   112112     1912   577536        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [12292]    33 12292    60815    32497   466944        0             0 nginx
Nov 23 03:48:50 ubuntu-server-18 kernel: [12293]    33 12293    61214    32910   471040        0             0 nginx
Nov 23 03:48:50 ubuntu-server-18 kernel: [12294]    33 12294    44113     4358   233472        0             0 nginx
Nov 23 03:48:50 ubuntu-server-18 kernel: [23744]    33 23744   152297    42951   978944        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24231]    33 24231   149576    40587   954368        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24245]    33 24245   160604    50698  1024000        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24247]    33 24247   150409    34720   888832        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24251]    33 24251   149541    39766   929792        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24253]    33 24253   149987    33909   880640        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24255]    33 24255   149565    33360   872448        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24261]    33 24261   149283    34006   892928        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24270]    33 24270   151926    35619   905216        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24272]    33 24272   151055    34804   901120        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24280]    33 24280   149279    33033   872448        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24474]    33 24474   149977    41005   942080        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24480]    33 24480   160875    44150   958464        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24481]    33 24481   155125    39199   929792        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24494]    33 24494   130327    32679   851968        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24501]    33 24501   149217    32395   872448        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24711]    33 24711   167027    43212   954368        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24716]    33 24716   130119    30374   839680        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24728]    33 24728   129974    30180   839680        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24729]    33 24729   129980    30295   835584        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24730]    33 24730   130061    30360   835584        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24731]    33 24731   129492    31333   839680        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24732]    33 24732   129987    30500   839680        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24733]    33 24733   129785    31073   839680        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24735]    33 24735   114592    14326   716800        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24736]    33 24736   148728    30660   851968        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24737]    33 24737   130017    30366   839680        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24739]    33 24739   119261    19469   741376        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24740]    33 24740   140396    21720   778240        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24742]    33 24742   151672    34753   892928        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24777]    33 24777   129731    29546   811008        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24779]    33 24779   129731    29562   811008        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24780]    33 24780   129731    29537   811008        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24783]    33 24783   129731    29554   811008        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24784]    33 24784   129731    29554   811008        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24785]    33 24785   114039    14515   704512        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24786]    33 24786   115559    13569   679936        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24791]    33 24791   120167    18244   716800        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24792]    33 24792   120679    18849   720896        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24793]    33 24793   120679    18729   720896        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24794]    33 24794   120679    18793   720896        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24795]    33 24795   119143    16921   708608        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24797]    33 24797   120167    18172   716800        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24798]    33 24798   119143    16921   708608        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24807]    33 24807   116039    12175   667648        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24808]    33 24808   116039    12945   671744        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24809]    33 24809   117607    14883   696320        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24810]    33 24810   117607    15484   696320        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24811]    33 24811   117575    15597   696320        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24942]    33 24942   113151     5722   630784        0             0 php-fpm7.4
Nov 23 03:48:50 ubuntu-server-18 kernel: [24978]   111 24978   415917    97861  1253376        0             0 mysqld
Nov 23 03:48:50 ubuntu-server-18 kernel: Out of memory: Kill process 24978 (mysqld) score 99 or sacrifice child
Nov 23 03:48:50 ubuntu-server-18 kernel: Killed process 24978 (mysqld) total-vm:1663668kB, anon-rss:391444kB, file-rss:0kB, shmem-rss:0kB
Nov 23 03:48:50 ubuntu-server-18 kernel: oom_reaper: reaped process 24978 (mysqld), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
Nov 23 03:48:50 ubuntu-server-18 systemd[1]: mysql.service: Main process exited, code=killed, status=9/KILL
Nov 23 03:48:50 ubuntu-server-18 systemd[1]: mysql.service: Failed with result 'signal'.
Nov 23 03:48:50 ubuntu-server-18 systemd[1]: mysql.service: Service hold-off time over, scheduling restart.
Nov 23 03:48:50 ubuntu-server-18 systemd[1]: mysql.service: Scheduled restart job, restart counter is at 3.
-- Subject: Automatic restarting of a unit has been scheduled
-- Defined-By: systemd

----- 更新（服务器配置）-----

这是我的 PHP 设置

pm.max_children = 50 
pm.start_servers = 22 
pm.min_spare_servers = 15 
pm.max_spare_servers = 30  
pm.max_requests = 300

MySql 设置 /etc/mysql/mysql.conf.d/mysqld.cnf

[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address        = 127.0.0.1
#
# * Fine Tuning
#
key_buffer_size     = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover-options  = BACKUP
#max_connections        = 100
#table_open_cache       = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit   = 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Here you can see queries with especially long duration
#slow_query_log     = 1
#slow_query_log_file    = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
expire_logs_days    = 10
max_binlog_size   = 100M
#binlog_do_db       = include_database_name
#binlog_ignore_db   = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem

我应该在哪里定义 innodb_buffer_pool 和 max_connections？

查看 Hetzner 图表。当 MySql 被杀死时，我发现了一些奇怪的事情。

Answer 1

4GB 是一台相当小的机器。

• 减少 nginx 允许生成的 PHP 子进程的数量 —— 可能减少到只有 20 个。
• 减少 MySQL 的 innodb_buffer_pool。
• 减少 MySQL 的 max_connections。