PROCESSLIST

PROCESSLIST, just like SHOW PROCESSLIST, is used to view the requests that are being handled.

The PROCESSLIST table has additional columns not present in SHOW PROCESSLIST:

  • A MEM column to show the memory used by the request that is being processed, in bytes.
  • A TxnStart column to show the start time of the transaction
USE information_schema; DESC processlist;
+----------+---------------------+------+------+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------+---------------------+------+------+---------+-------+ | ID | bigint(21) unsigned | NO | | 0 | | | USER | varchar(16) | NO | | | | | HOST | varchar(64) | NO | | | | | DB | varchar(64) | YES | | NULL | | | COMMAND | varchar(16) | NO | | | | | TIME | int(7) | NO | | 0 | | | STATE | varchar(7) | YES | | NULL | | | INFO | binary(512) | YES | | NULL | | | MEM | bigint(21) unsigned | YES | | NULL | | | TxnStart | varchar(64) | NO | | | | +----------+---------------------+------+------+---------+-------+ 10 rows in set (0.00 sec)
SELECT * FROM processlist\G
*************************** 1. row *************************** ID: 16 USER: root HOST: 127.0.0.1 DB: information_schema COMMAND: Query TIME: 0 STATE: autocommit INFO: SELECT * FROM processlist MEM: 0 TxnStart: 1 row in set (0.00 sec)

Fields in the PROCESSLIST table are described as follows:

  • ID: The ID of the user connection.
  • USER: The name of the user who is executing PROCESS.
  • HOST: The address that the user is connecting to.
  • DB: The name of the currently connected default database.
  • COMMAND: The command type that PROCESS is executing.
  • TIME: The current execution duration of PROCESS, in seconds.
  • STATE: The current connection state.
  • INFO: The requested statement that is being processed.
  • MEM: The memory used by the request that is being processed, in bytes.
  • TxnStart: The start time of the transaction.

CLUSTER_PROCESSLIST

CLUSTER_PROCESSLIST is the cluster system table corresponding to PROCESSLIST. It is used to query the PROCESSLIST information of all TiDB nodes in the cluster. The table schema of CLUSTER_PROCESSLIST has one more column than PROCESSLIST, the INSTANCE column, which stores the address of the TiDB node this row of data is from.

SELECT * FROM information_schema.cluster_processlist;
+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ | INSTANCE | ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | MEM | TxnStart | +-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+ | 10.0.1.22:10080 | 150 | u1 | 10.0.1.1 | test | Query | 0 | autocommit | select count(*) from usertable | 372 | 05-28 03:54:21.230(416976223923077223) | | 10.0.1.22:10080 | 138 | root | 10.0.1.1 | test | Query | 0 | autocommit | SELECT * FROM information_schema.cluster_processlist | 0 | 05-28 03:54:21.230(416976223923077220) | | 10.0.1.22:10080 | 151 | u1 | 10.0.1.1 | test | Query | 0 | autocommit | select count(*) from usertable | 372 | 05-28 03:54:21.230(416976223923077224) | | 10.0.1.21:10080 | 15 | u2 | 10.0.1.1 | test | Query | 0 | autocommit | select max(field0) from usertable | 496 | 05-28 03:54:21.230(416976223923077222) | | 10.0.1.21:10080 | 14 | u2 | 10.0.1.1 | test | Query | 0 | autocommit | select max(field0) from usertable | 496 | 05-28 03:54:21.230(416976223923077225) | +-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+