我试图找出正在使用我的RAM的内存。我做了一些检查，看起来mysqld引起了较高的RAM使用率。的输出free -g，htop，top，showprocesslist;没有太大的帮助。
免费-g
total used free shared buffers cached
Mem: 125 120 5 0 1 101
-/+ buffers/cache: 17 108
Swap: 0 0 0
如果我是对的，这表明我在125 GB内存中只有5 GB可用内存。
停止
1 [||| 4.6%] 9 [ 0.0%] 17 [|| 1.4%] 25 [ 0.0%]
2 [||||||||||||||||||||||| 44.4%] 10 [ 0.0%] 18 [ 0.0%] 26 [| 0.5%]
3 [||||||| 12.4%] 11 [| 0.5%] 19 [ 0.0%] 27 [ 0.0%]
4 [||||| 7.5%] 12 [ 0.0%] 20 [ 0.0%] 28 [ 0.0%]
5 [|||||||| 14.2%] 13 [ 0.0%] 21 [ 0.0%] 29 [ 0.0%]
6 [|||| 4.8%] 14 [ 0.0%] 22 [| 0.5%] 30 [ 0.0%]
7 [ 0.0%] 15 [| 0.5%] 23 [|| 2.4%] 31 [ 0.0%]
8 [| 0.5%] 16 [| 0.9%] 24 [|||| 5.6%] 32 [ 0.0%]
Mem[||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||17367/128886MB] Tasks: 93, 90 thr; 2 running
Swp[ 0/1021MB] Load average: 1.01 0.96 0.97
Uptime: 18 days, 05:43:05
PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command
27655 mysql 20 0 66.8G 6166M 11220 S 69.2 4.8 5:25.06 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
28300 mysql 20 0 66.8G 6166M 11220 R 33.4 4.8 0:51.03 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27743 mysql 20 0 66.8G 6166M 11220 S 35.8 4.8 1:26.46 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
28064 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 1:33.48 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
28007 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 1:27.01 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27727 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.44 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27692 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.01 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27697 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.03 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27725 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.39 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27724 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.08 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27691 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27693 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.11 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27694 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.06 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27695 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.10 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27696 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.08 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27698 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.02 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27699 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.01 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27700 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.01 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27726 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
27739 mysql 20 0 66.8G 6166M 11220 S 0.0 4.8 0:00.00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysql
8395 clamav 20 0 799M 534M 24264 S 0.0 0.4 0:00.00 /usr/sbin/clamd --foreground=true
8266 clamav 20 0 799M 534M 24264 S 0.0 0.4 9:07.15 /usr/sbin/clamd --foreground=true
12977 amavis 20 0 316M 120M 8448 S 0.0 0.1 0:01.46 /usr/sbin/amavisd-new (ch10-avail)
8190 amavis 20 0 316M 120M 8448 S 0.0 0.1 0:01.64 /usr/sbin/amavisd-new (ch11-avail)
24641 amavis 20 0 242M 116M 5692 S 0.0 0.1 0:11.26 /usr/sbin/amavisd-new (master)
htop输出表明mysqld导致较高的RAM使用率，不是吗？
最佳
top - 18:12:15 up 18 days, 5:55, 1 user, load average: 0.98, 1.00, 1.00
Tasks: 475 total, 1 running, 474 sleeping, 0 stopped, 0 zombie
%Cpu(s): 2.7 us, 0.2 sy, 0.0 ni, 97.1 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 13198007+total, 12738310+used, 4596968 free, 1927068 buffers
KiB Swap: 1046520 total, 0 used, 1046520 free. 10698358+cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
27655 mysql 20 0 66.840g 6.662g 11220 S 62.3 5.3 12:50.24 mysqld
22288 web1 20 0 367640 75964 52492 S 29.2 0.1 6:55.78 php-cgi
16897 www-data 20 0 2067372 28632 7380 S 1.0 0.0 7:20.03 apache2
29318 root 20 0 26512 3440 2576 R 0.7 0.0 0:01.49 top
31235 root 20 0 775232 12736 5984 S 0.3 0.0 16:57.05 fail2ban-server
1 root 20 0 177980 6764 3256 S 0.0 0.0 0:55.74 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.13 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:04.97 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
6 root 20 0 0 0 0 S 0.0 0.0 2:56.16 kworker/u64:0
8 root 20 0 0 0 0 S 0.0 0.0 16:31.60 rcu_sched
9 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh
10 root rt 0 0 0 0 S 0.0 0.0 0:00.95 migration/0
但是随后top显示mysqld仅使用5.3％的RAM。
显示过程清单；
Kill Kill 734 phpmyadmin localhost NULL Sleep 0 NULL
Kill Kill 735 root localhost NULL Query 0 NULL SHOW PROCESSLIST
显示过程清单；为空，这是事实，因为只有一个网站正在开发中，没有任何流量。
mysqltuner.pl
-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 24m 14s (175K q [120.627 qps], 1K conn, TX: 2G, RX: 37M)
[--] Reads / Writes: 95% / 5%
[--] Binary logging is disabled
[--] Physical Memory : 125.9G
[--] Max MySQL memory : 62.4G
[--] Other process memory: 1.1G
[--] Total buffers: 62.0G global + 2.7M per thread (151 max threads)
[--] P_S Max memory usage: 0B
[--] Galera GCache Max memory usage: 0B
[OK] Maximum reached memory usage: 62.0G (49.29% of installed RAM)
[OK] Maximum possible memory usage: 62.4G (49.60% of installed RAM)
[OK] Overall possible memory usage with other process is compatible with memory available
[OK] Slow queries: 0% (0/175K)
[OK] Highest usage of available connections: 2% (4/151)
[OK] Aborted connections: 0.42% (5/1182)
[!!] name resolution is active : a reverse name resolution is made for each new connection and can reduce performance
[OK] Query cache is disabled by default due to mutex contention on multiprocessor machines.
[OK] Sorts requiring temporary tables: 1% (988 temp sorts / 57K sorts)
[OK] No joins without indexes
[!!] Temporary tables created on disk: 81% (13K on disk / 16K total)
[OK] Thread cache hit rate: 99% (4 created / 1K connections)
[OK] Table cache hit rate: 96% (209 open / 216 opened)
[OK] Open file limit used: 21% (225/1K)
[OK] Table locks acquired immediately: 100% (204K immediate / 204K locks)
（...）
-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
Control warning line(s) into /var/log/mysql/error.log file
Control error line(s) into /var/log/mysql/error.log file
MySQL started within last 24 hours - recommendations may be inaccurate
Enable the slow query log to troubleshoot bad queries
Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
When making adjustments, make tmp_table_size/max_heap_table_size equal
Reduce your SELECT DISTINCT queries which have no LIMIT clause
Consider installing Sys schema from https://github.com/mysql/mysql-sys
Read this before changing innodb_log_file_size and/or innodb_log_files_in_group: bit.ly/2wgkDvS
Variables to adjust:
tmp_table_size (> 16M)
max_heap_table_size (> 16M)
innodb_log_file_size should be (=7G) if possible, so InnoDB total log files size equals to 25% of buffer pool size.
mysql error.log为空。有什么想法吗？
对于RAM，从free命令输出中，您已经获得了free + buffers + cached-> 5 + 1 + 101 = 107 GB。
因此，实际上您的程序正在使用，再次从free输出中使用了120GB RAM-107 GB可用+缓冲区+缓存= 13GB
内核可以随时为其他需求回收缓冲区和缓存，并且通常会随着时间的增长而增长。但是，随着它们的增长，当内存不足时，它们也会收缩。
正如你也可以看到，无论是在free，ps和mysqltuner输出，MySQL的RAM的使用似乎主要缓冲区。
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