MySQL max_connection值

Question

问题

1. 我有一台12 GB的带有apache & myqsl的机器，我可以将apache设置为150，这会导致mysql中的50 max_client出现瓶颈吗？
2. 我应该设置什么值来平衡mysql、max_connection或apache max_client，并为我的站点优化性能？

谢谢。

请查看我的mysql配置和mysqltuner结果。

[mysqld]
innodb_file_per_table
datadir=/var/lib/mysql
tmpdir=/var/lib/mysqltmp
socket=/var/lib/mysql/mysql.sock
skip-locking
skip-name-resolve
table_cache=1024
table_definition_cache = 1024
thread_cache_size=16
back_log=100
max_connect_errors=10000
open-files-limit=20000
interactive_timeout=30
wait_timeout=60
max_connections=50
skip-name-resolve

# Slow Query Log Settings
log-slow-queries=/var/lib/mysqllogs/slow-log
long_query_time=5
log-queries-not-using-indexes

# Global, Non Engine-Specific Buffers
max_allowed_packet=16M
tmp_table_size=1768M
max_heap_table_size=1768M
query_cache_size=32M

# Per-Thread Buffers
sort_buffer_size=1M
read_buffer_size=1M
read_rnd_buffer_size=8M
join_buffer_size=32M

# MyISAM
key_buffer_size=64M
myisam_sort_buffer_size=64M

# InnoDB
innodb_log_file_size=100M
innodb_buffer_pool_size=1512M

[mysql.server]
user=mysql
#basedir=/var/lib

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
open-files-limit=65535

 >>  Bug reports, feature requests, and downloads at http://mysqltuner.com/
 >>  Run with '--help' for additional options and output filtering

-------- General Statistics --------------------------------------------------
[--] Skipped version check for MySQLTuner script
[OK] Currently running supported MySQL version 5.1.73-log
[OK] Operating on 64-bit architecture

-------- Storage Engine Statistics -------------------------------------------
[--] Status: -Archive -BDB -Federated
+InnoDB -ISAM -NDBCluster
[--] Data in MyISAM tables: 48M (Tables: 124)
[--] Data in InnoDB tables: 2G (Tables: 179)
[!!] Total fragmented tables: 39

-------- Security Recommendations  -------------------------------------------
[OK] All database users have passwords assigned

-------- Performance Metrics -------------------------------------------------
[--] Up for: 5d 14h 27m 2s (20M q [41.828 qps], 1M conn, TX: 275B, RX:
5B)
[--] Reads / Writes: 75% / 25%
[--] Total buffers: 3.3G global + 42.2M per thread (50 max threads)
[OK] Maximum possible memory usage: 5.4G (46% of installed RAM)
[!!] Slow queries: 6% (1M/20M)
[OK] Highest usage of available connections: 74% (37/50)
[OK] Key buffer size / total MyISAM indexes: 64.0M/31.1M
[OK] Key buffer hit rate: 99.9% (11M cached / 7K reads)
[OK] Query cache efficiency: 68.1% (10M cached / 14M selects)
[!!] Query cache prunes per day: 42514
[OK] Sorts requiring temporary tables: 0% (4K temp sorts / 1M sorts)
[!!] Joins performed without indexes: 73669
[OK] Temporary tables created on disk: 6% (136K on disk / 2M total)
[OK] Thread cache hit rate: 99% (155 created / 1M connections)
[OK] Table cache hit rate: 74% (974 open / 1K opened)
[OK] Open file limit used: 0% (453/65K)
[OK] Table locks acquired immediately: 99% (18M immediate / 18M locks)
[!!] InnoDB data size / buffer pool: 2.3G/1.5G

-------- Recommendations -----------------------------------------------------
General recommendations:
    Run OPTIMIZE TABLE to defragment tables for better performance
    Adjust your join queries to always utilize indexes
Variables to adjust:
    query_cache_size (> 64M)
    join_buffer_size (> 32.0M, or always use indexes with joins)
    innodb_buffer_pool_size (>= 2G)

Answer 1

Max_connections是MySQL服务器允许的并发连接总数。如果您正在获得Too many connections' error，这意味着您已经达到了这个极限。

此外，您应该在一段时间内观察threads_running变量值，以确定'max_connections‘的确切值。

您可以将max_connection值视为

MaxValue (Threads_running)‘+ 10 = Max_connections