13.7.5.29 SHOW PROCESSLIST Statement

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SHOW [FULL] PROCESSLIST

The MySQL process list indicates the operations currently being performed by the set of threads executing within the server. The SHOW PROCESSLIST statement is one source of process information. For a comparison of this statement with other sources, see Sources of Process Information.

If you have the PROCESS privilege, you can see all threads, even those belonging to other users. Otherwise (without the PROCESS privilege), nonanonymous users have access to information about their own threads but not threads for other users, and anonymous users have no access to thread information.

Without the FULL keyword, SHOW PROCESSLIST displays only the first 100 characters of each statement in the Info field.

The SHOW PROCESSLIST statement is very useful if you get the “too many connections” error message and want to find out what is going on. MySQL reserves one extra connection to be used by accounts that have the SUPER privilege, to ensure that administrators should always be able to connect and check the system (assuming that you are not giving this privilege to all your users).

Threads can be killed with the KILL statement. See Section 13.7.6.4, “KILL Statement”.

Example of SHOW PROCESSLIST output:

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mysql> SHOW FULL PROCESSLIST\G
*************************** 1. row ***************************
     Id: 1
   User: system user
   Host:
     db: NULL
Command: Connect
   Time: 1030455
  State: Waiting for master to send event
   Info: NULL
*************************** 2. row ***************************
     Id: 2
   User: system user
   Host:
     db: NULL
Command: Connect
   Time: 1004
  State: Has read all relay log; waiting for the slave
         I/O thread to update it
   Info: NULL
*************************** 3. row ***************************
     Id: 3112
   User: replikator
   Host: artemis:2204
     db: NULL
Command: Binlog Dump
   Time: 2144
  State: Has sent all binlog to slave; waiting for binlog to be updated
   Info: NULL
*************************** 4. row ***************************
     Id: 3113
   User: replikator
   Host: iconnect2:45781
     db: NULL
Command: Binlog Dump
   Time: 2086
  State: Has sent all binlog to slave; waiting for binlog to be updated
   Info: NULL
*************************** 5. row ***************************
     Id: 3123
   User: stefan
   Host: localhost
     db: apollon
Command: Query
   Time: 0
  State: NULL
   Info: SHOW FULL PROCESSLIST

SHOW PROCESSLIST output has these columns:

• Id

  The connection identifier. This is the same value displayed in the ID column of the INFORMATION_SCHEMA PROCESSLIST table, displayed in the PROCESSLIST_ID column of the Performance Schema threads table, and returned by the CONNECTION_ID() function within the thread.

• User

  The MySQL user who issued the statement. A value of system user refers to a nonclient thread spawned by the server to handle tasks internally, for example, a delayed-row handler thread or an I/O or SQL thread used on replica hosts. For system user, there is no host specified in the Host column. unauthenticated user refers to a thread that has become associated with a client connection but for which authentication of the client user has not yet occurred. event_scheduler refers to the thread that monitors scheduled events (see Section 23.4, “Using the Event Scheduler”).

• Host

  The host name of the client issuing the statement (except for system user, for which there is no host). The host name for TCP/IP connections is reported in host_name:client_port format to make it easier to determine which client is doing what.

• db

  The default database for the thread, or NULL if none has been selected.

• Command

  The type of command the thread is executing on behalf of the client, or Sleep if the session is idle. For descriptions of thread commands, see Section 8.14, “Examining Server Thread (Process) Information”. The value of this column corresponds to the COM_xxx commands of the client/server protocol and Com_xxx status variables. See Section 5.1.9, “Server Status Variables”.

• Time

  The time in seconds that the thread has been in its current state. For a replica SQL thread, the value is the number of seconds between the timestamp of the last replicated event and the real time of the replica host. See Section 16.2.3, “Replication Threads”.

• State

  An action, event, or state that indicates what the thread is doing. For descriptions of State values, see Section 8.14, “Examining Server Thread (Process) Information”.

  Most states correspond to very quick operations. If a thread stays in a given state for many seconds, there might be a problem that needs to be investigated.

• Info

  The statement the thread is executing, or NULL if it is executing no statement. The statement might be the one sent to the server, or an innermost statement if the statement executes other statements. For example, if a CALL statement executes a stored procedure that is executing a SELECT statement, the Info value shows the SELECT statement.