瑞客论坛2019老男孩mysql dba6期1

1、2019/5/25APP S TO:PUR ESCOPEDETAILSmax_connectionsmax_connections1/4 SHOW GLOBAL VARIABLES LIKE max_connections;+-+-+| Variable_name | Value |+-+-+| max_connections | 200 |+-+-+1 row in set (0.00 sec) SELECT * FROM information_schema.GLOBAL_VARIABLES WHERE VARIABLE_NAME = max_connections;+-+-+| VARI

2、ABLE_NAME | VARIABLE_VALUE |+-+-+| MAX_CONNECTIONS | 200|+-+-+1 row in set (0.00 sec)SUPER2019/5/25Theum er of allowed connections can be changed either using a restart setting the max_connectionsoption heconguration le:or dynamically like:The max_connections option is relat able_open_cache and open

3、_ s_limit, and may adjustmax connections downwards when number of le descriptors available.is started, if it is estimated t the value is too large compared to theIf no more connections are available, the following error is returned when connection attempts are made:See also:Error: 1040, Too many con

4、nections m I getting a message g t there are too many connections when logging o ? Server: What is theum Value for max_connections on Linux?Connection_errors_max_connectionsMySQL 5.6 and later, you can use the Connecti ors max connections global s us variable to see how many times connection attempt

5、s have failed due to theum number of connections being reached:Max_used_connectionsThe global s us vMax used connections can be used to determine theum number of concurrentconnections sincewas last restarted:2/4 SHOW GLOBAL S US LIKE Max_used_connections;+-+-+| Variable_name| Value |+-+-+| Max_used_

6、connections | 102 |+-+-+1 row in set (0.00 sec) SELECT * FROM information_schema.GLOBAL_S US WHERE VARIABLE_NAME = Max_used_connections;+-+-+| VARIABLE_NAME| VARIABLE_VALUE | SHOW GLOBAL S US LIKE Connection_errors_max_connections;+-+-+| Variable_name| Value |+-+-+| Connection_errors_max_connections

7、 | 10 |+-+-+1 row in set (0.00 sec) SELECT * FROM information_schema.GLOBAL_S US WHERE VARIABLE_NAME = Connection_errors_max_con+-+-+| VARIABLE_NAME| VARIABLE_VALUE |+-+-+| CONNECTION_ERRORS_MAX_CONNECTIONS | 10|+-+-+1 row in set (0.00 sec)ERROR 1040 (HY000): Too many connectionsFor this reason grea

8、t care should o be taken if max_connections is in eased without restarting: running out of le descriptors can for ex le cause updates not to be logged he binary log. SET GLOBAL max_connections = 100; dm nnections = 200The Information Schema table GLOBAL_VARIABLES is available ySQL 5.1 and later.2019

9、/5/25If this gets close to max_connections it is a sign t you either need to increase max_connections or make sure t connections disconnect quicker.Threads_connectedThreads connected is the number of current connections and can be found as:See also: um Connection Limit Nearing Or ReachedThreads_runn

10、ingThreads_running is the number of non-idle threads. The current number of running threads can be found as:If the number of running eads is high, you may experien contention i es. threads is to make sure t each query is as eective as sible.ay to reduce the number of runningREFERENNOTE:1023341.1 - E

11、rror: 1040, Too many connectionsNOTE:1023582.1 - NOTE:1024093.1 - NOTE:1385400.1 - NOTE:1322541.1 - NOTE:1501924.1 - NOTE:1023195.1 - Why cm I getting a message saying t there are too many connections when logging o?um Connection Limit Server: What is theg Or Reachedum Value for max_connections on L

12、inux?Server Variable: table_open_cache (Formerly Called table_cache)er: table_opehe Value is Not the Same as the Value Set Inf on Linuxreate morethreads on my Red Hat server?NOTE:1484095.1 - Error - Cant Create A New Thread (errno 11)htt /doc/refman/5.6/en/server-s em-variables.html# var_max_connect

13、ionshtt /doc/refman/5.6/en/server-s us-variables.html#s var_Max_used_connections3/4 SHOW GLOBAL S US LIKE Threads_running;+-+-+| Variable_name | Value |+-+-+| Threads_running | 2|+-+-+1 row in set (0.00 sec) SELECT * FROM information_schema.GLOBAL_S US WHERE VARIABLE_NAME = Threads_running;+-+-+| VA

14、RIABLE_NAME | VARIABLE_VALUE |+-+-+| THREADS_RUNNING | 2|+-+-+1 row in set (0.00 sec) SHOW GLOBAL S US LIKE Threads_connected;+-+-+| Variable_name| Value |+-+-+| Threads_connected | 4|+-+-+1 row in set (0.00 sec) SELECT * FROM information_schema.GLOBAL_S US WHERE VARIABLE_NAME = Threads_connected;+-+-+| VARIABLE_NAME| VARIABLE_VALUE |+-+-+| THREADS_CONNECTED | 4|+-+-+1 row in set (0.00 sec)Unless you are using a connection pool, make sure to disconnect fromas soon as the connection is dithk. If you cannot change the lication to disconnect, you can use eractive timeout an