Public bug reported:
(this bug has been reproduced in an LXC container running on Arch Linux,
that's why the strange kernel version)
On Ubuntu 18.04, systemd runs mysqld in two steps. First:
ExecStartPre=/usr/share/mysql/mysql-systemd-start pre
In this script, one of the steps is: mysqld --verbose --help --innodb-
read-only
Then:
ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid
It's the first mysqld (with --help) which is a problem. The problem
happens because, due to PermissionsStartOnly=true, systemd runs
ExecStartPre commands with insane limits. In particular:
Aug 08 18:19:23 mysql57 bash[13131]: core file size (blocks, -c)
unlimited
Aug 08 18:19:23 mysql57 bash[13131]: data seg size (kbytes, -d)
unlimited
Aug 08 18:19:23 mysql57 bash[13131]: scheduling priority (-e) 0
Aug 08 18:19:23 mysql57 bash[13131]: file size (blocks, -f)
unlimited
Aug 08 18:19:23 mysql57 bash[13131]: pending signals (-i) 63701
Aug 08 18:19:23 mysql57 bash[13131]: max locked memory (kbytes, -l) 16384
Aug 08 18:19:23 mysql57 bash[13131]: max memory size (kbytes, -m)
unlimited
Aug 08 18:19:23 mysql57 bash[13131]: open files (-n)
1073741816 <--- see this?
Aug 08 18:19:23 mysql57 bash[13131]: pipe size (512 bytes, -p) 8
Aug 08 18:19:23 mysql57 bash[13131]: POSIX message queues (bytes, -q) 819200
Aug 08 18:19:23 mysql57 bash[13131]: real-time priority (-r) 0
Aug 08 18:19:23 mysql57 bash[13131]: stack size (kbytes, -s) 8192
Aug 08 18:19:23 mysql57 bash[13131]: cpu time (seconds, -t)
unlimited
Aug 08 18:19:23 mysql57 bash[13131]: max user processes (-u) 63701
Aug 08 18:19:23 mysql57 bash[13131]: virtual memory (kbytes, -v)
unlimited
Aug 08 18:19:23 mysql57 bash[13131]: file locks (-x)
unlimited
When running with such a high "ulimit -n" (again, this is something
which systemd does by default for ExecStartPre), "mysqld --help"
consumes unimaginable amounts of memory and even causes swapping and
page allocation failures on my PC with 16 GB of RAM.
Workaround in /etc/systemd/system/mysql.service.d/override.conf:
[Service]
ExecStartPre=
ExecStartPre=/bin/sh -c 'ulimit -n 1024 ; /usr/share/mysql/mysql-systemd-start
pre'
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: mysql-server-5.7 5.7.27-0ubuntu0.18.04.1
Uname: Linux 5.2.5-arch1-1-ARCH x86_64
ApportVersion: 2.20.9-0ubuntu7.7
Architecture: amd64
Date: Thu Aug 8 18:29:38 2019
Logs.var.log.daemon.log:
MySQLConf.etc.mysql.conf.d.mysql.cnf: [mysql]
MySQLConf.etc.mysql.conf.d.mysqldump.cnf:
[mysqldump]
quick
quote-names
max_allowed_packet = 16M
MySQLConf.etc.mysql.mysql.conf.d.mysqld_safe_syslog.cnf:
[mysqld_safe]
syslog
MySQLVarLibDirListing: False
ProcEnviron:
LANG=en_US.UTF-8
TERM=xterm-256color
SHELL=/bin/bash
XDG_RUNTIME_DIR=<set>
PATH=(custom, no user)
SourcePackage: mysql-5.7
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.mysql.mysql.conf.d.mysqld.cnf: [modified]
mtime.conffile..etc.mysql.mysql.conf.d.mysqld.cnf: 2019-08-08T17:51:27.927907
** Affects: mysql-5.7 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug bionic
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https://bugs.launchpad.net/bugs/1839527
Title:
mysqld eats more than 16 GB of memory on startup
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