【发布时间】：2014-05-06 22:19:47
【问题描述】：
我正在管理一个提供流媒体视频的网站，该网站正在关闭：
Intel(R) Xeon(R) CPU E31220 @ 3.10GHz
16 GB 内存
2 x 2TB RAID1
1gbit 未计量带宽不是问题，因为使用量仅为 150-250mbit 等。
在这台机器上，我运行以下命令： - apache 托管 [url]www.domain.com[/url] - mysql 服务器 (apt-get install mysql-server)
一切都很顺利，除了现在有 200 人在任何给定时间流式传输视频。所以现在我注意到网站加载速度较慢。我相信这是因为 mysql 正在使用 100% cpu。下面我粘贴了我的顶部，还有我的 mysql 设置。有人可以帮我设置 mysql 设置来减慢速度吗？
我确实意识到在某些时候我需要自己将 mysql 服务器移动到另一台机器上，但我仍然认为在我即将发布的当前设置下，即使在独立机器上它仍然会使用 100% cpu。 .所以我认为需要更改设置？或者有人可以指导我。此外，我无法降低 wait_timeout，因为当我这样做时，它会导致视频转换脚本出错，该脚本会获取视频并转换它们，有时可能需要一段时间，所以我不知道这是一个问题还是什么
my.cnf:
# * Fine Tuning
#
max_allowed_packet = 16M
thread_stack = 1M
thread_cache_size = 50
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
max_connections = 1000
wait_timeout = 20000
tmp_table_size = 500M
max_heap_table_size = 1000M
table_cache = 1000
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit = 4M
query_cache_size = 64M
#
# * 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
#log_slow_queries = /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
[mysqldump]
quick
quote-names
max_allowed_packet = 16M
[mysql]
#no-auto-rehash # faster start of mysql but no tab completition
[isamchk]
key_buffer_size = 64M
----------------------------------------
>> MySQLTuner 1.1.1 - Major Hayden <major@mhtx.net>
>> Bug reports, feature requests, and downloads at [url]http://mysqltuner.com/[/url]
>> Run with '--help' for additional options and output filtering
[!!] Successfully authenticated with no password - SECURITY RISK!
-------- General Statistics --------------------------------------------------
[--] Skipped version check for MySQLTuner script
[OK] Currently running supported MySQL version 5.5.37-0ubuntu0.13.10.1
[OK] Operating on 64-bit architecture
-------- Storage Engine Statistics -------------------------------------------
[--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster
[--] Data in MyISAM tables: 1G (Tables: 41)
[--] Data in PERFORMANCE_SCHEMA tables: 0B (Tables: 17)
[!!] InnoDB is enabled but isn't being used
[!!] Total fragmented tables: 4
-------- Security Recommendations -------------------------------------------
[OK] All database users have passwords assigned
-------- Performance Metrics -------------------------------------------------
[--] Up for: 22h 23m 46s (5M q [69.809 qps], 1M conn, TX: 8B, RX: 4B)
[--] Reads / Writes: 29% / 71%
[--] Total buffers: 716.0M global + 3.5M per thread (1000 max threads)
[OK] Maximum possible memory usage: 4.1G (26% of installed RAM)
[OK] Slow queries: 0% (2/5M)
[OK] Highest usage of available connections: 77% (775/1000)
[OK] Key buffer size / total MyISAM indexes: 8.0M/119.0M
[OK] Key buffer hit rate: 99.4% (33M cached / 208K reads)
[OK] Query cache efficiency: 67.6% (1M cached / 1M selects)
[OK] Query cache prunes per day: 0
[OK] Sorts requiring temporary tables: 0% (0 temp sorts / 921 sorts)
[!!] Temporary tables created on disk: 28% (244 on disk / 849 total)
[OK] Thread cache hit rate: 98% (17K created / 1M connections)
[OK] Table cache hit rate: 62% (428 open / 681 opened)
[OK] Open file limit used: 9% (476/5K)
[!!] Table locks acquired immediately: 55%
-------- Recommendations -----------------------------------------------------
General recommendations:
Add skip-innodb to MySQL configuration to disable InnoDB
Run OPTIMIZE TABLE to defragment tables for better performance
MySQL started within last 24 hours - recommendations may be inaccurate
Enable the slow query log to troubleshoot bad queries
Temporary table size is already large - reduce result set size
Reduce your SELECT DISTINCT queries without LIMIT clauses
Optimize queries and/or use InnoDB to reduce lock wait
-------------------------------------------------------
它说运行优化表，但我该怎么做？在网上我试图搜索并发现运行 mysql check 命令但我得到了
# mysqlcheck -u root -p --auto-repair --check --optimize --all-databases
Error: mysqlcheck doesn't support multiple contradicting commands.
此外，仅优化数据库是否安全？它不会伤害它还是什么？当然要先备份
我现在启用了慢查询日志，但目前还没有..
在某一时刻，Mysqltuner 说我已经达到了 996/1000 个连接.. 但是当我去提高 max_connections 到 2000 然后我重新启动 mysql 服务器时，网站变得比以前更慢.. 也许我应该不是重新启动mysql服务器而只是全局调整？
top - 23:27:42 up 11 days, 5:28, 3 users, load average: 2.41, 4.40, 5.97
Tasks: 269 total, 3 running, 265 sleeping, 0 stopped, 1 zombie
%Cpu(s): 24.3 us, 5.6 sy, 0.0 ni, 69.3 id, 0.3 wa, 0.0 hi, 0.5 si, 0.0 st
KiB Mem: 16408692 total, 16237624 used, 171068 free, 9552 buffers
KiB Swap: 15624184 total, 8220 used, 15615964 free, 15072644 cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
29178 mysql 20 0 2662m 73m 7280 S 100.4 0.5 4:49.03 /usr/sbin/mysqld
29428 daemon 20 0 544m 19m 7048 S 2.7 0.1 0:07.81 /usr/sbin/apache2 -k start
29943 daemon 20 0 543m 17m 5428 S 2.0 0.1 0:02.57 /usr/sbin/apache2 -k start
29945 daemon 20 0 543m 17m 5352 S 2.0 0.1 0:00.76 /usr/sbin/apache2 -k start
29672 daemon 20 0 543m 16m 4696 S 1.7 0.1 0:00.63 /usr/sbin/apache2 -k start
29792 daemon 20 0 544m 17m 5396 S 1.3 0.1 0:00.15 /usr/sbin/apache2 -k start
183 root 20 0 0 0 0 S 1.0 0.0 8:51.20 [md0_raid1]
29445 daemon 20 0 543m 16m 4700 S 0.7 0.1 0:01.04 /usr/sbin/apache2 -k start
29744 daemon 20 0 543m 16m 5384 S 0.7 0.1 0:00.23 /usr/sbin/apache2 -k start
7705 root 35 15 0 0 0 D 0.3 0.0 2:27.65 [md0_resync]
29435 daemon 20 0 543m 17m 5596 S 0.3 0.1 0:00.37 /usr/sbin/apache2 -k start
29451 daemon 20 0 543m 17m 5356 S 0.3 0.1 0:00.44 /usr/sbin/apache2 -k start
29453 daemon 20 0 0 0 0 Z 0.3 0.0 0:00.07 [apache2] <defunct>
29501 daemon 20 0 543m 16m 5324 S 0.3 0.1 0:00.10 /usr/sbin/apache2 -k start
29518 daemon 20 0 543m 17m 5948 S 0.3 0.1 0:00.31 /usr/sbin/apache2 -k start
29534 daemon 20 0 543m 17m 5456 S 0.3 0.1 0:00.42 /usr/sbin/apache2 -k start
29539 daemon 20 0 543m 16m 5348 S 0.3 0.1 0:00.24 /usr/sbin/apache2 -k start
29542 daemon 20 0 543m 16m 4680 S 0.3 0.1 0:00.51 /usr/sbin/apache2 -k start
29549 daemon 20 0 543m 17m 5352 S 0.3 0.1 0:00.90 /usr/sbin/apache2 -k start
29656 daemon 20 0 543m 16m 4792 S 0.3 0.1 0:00.25 /usr/sbin/apache2 -k start
29673 daemon 20 0 543m 16m 5392 R 0.3 0.1 0:00.20 /usr/sbin/apache2 -k start
29682 daemon 20 0 543m 16m 4704 S 0.3 0.1 0:00.58 /usr/sbin/apache2 -k start
29791 daemon 20 0 543m 17m 5392 S 0.3 0.1 0:00.81 /usr/sbin/apache2 -k start
29793 daemon 20 0 543m 17m 5712 S 0.3 0.1 0:00.12 /usr/sbin/apache2 -k start
29926 daemon 20 0 543m 16m 4704 S 0.3 0.1 0:00.44 /usr/sbin/apache2 -k start
29956 daemon 20 0 543m 16m 4700 S 0.3 0.1 0:00.33 /usr/sbin/apache2 -k start
=====================================
# free -tm
total used free shared buffers cached
Mem: 16024 15861 162 0 4 14351
-/+ buffers/cache: 1506 14517
Swap: 15257 8 15249
Total: 31282 15870 15411
补充问题： 如果我确实将 mysql 移动到自己的机器上，硬盘驱动器应该是 ssds 吗？这对mysql更好吗？并且 32 GB 的内存就足够了
数据库中最大的东西是会话表，到目前为止它可以达到 1.5 gb。但我清除它并且数据库缩小到 100mb 以下
【问题讨论】：
-
这个问题应该可以在Server Fault问。
-
增加查询缓存后，mysql仍然使用100% cpu。我将 key_buffer_size 增加到 256mb，现在它的表现稍微好一点，但总体上仍然有时使用 50% 到 90% 的 cpu。这是正常的吗？
标签： mysql apache video-streaming cpu-usage