进程列表
The
PROCESSLIST
table provides information about which threads are running.
Name |
Name |
Remarks |
|---|---|---|
|
|
MySQL extension |
|
|
MySQL extension |
|
|
MySQL extension |
|
|
MySQL extension |
|
|
MySQL extension |
|
|
MySQL extension |
|
|
MySQL extension |
|
|
MySQL extension |
For an extensive description of the table columns, see
Section 13.7.5.29, “SHOW PROCESSLIST Syntax”
.
Notes
:
-
The
PROCESSLIST
table is a nonstandard table. -
Like the output from the corresponding
SHOW
statement, the
PROCESSLIST
table will only show information about your own threads, unless you have the
PROCESS
privilege, in which case you will see information about other threads, too. As an anonymous user, you cannot see any rows at all. -
If an SQL statement refers to
INFORMATION_SCHEMA.PROCESSLIST
, MySQL populates the entire table once, when statement execution begins, so there is read consistency during the statement. There is no read consistency for a multi-statement transaction, though. -
Process information is also available from the
performance_schema.threads
table. However, access to
threads
does not require a mutex and has minimal impact on server performance.
INFORMATION_SCHEMA.PROCESSLIST
and
SHOW PROCESSLIST
have negative performance consequences because they require a mutex.
threads
also shows information about background threads, which
INFORMATION_SCHEMA.PROCESSLIST
and
SHOW PROCESSLIST
do not. This means that
threads
can be used to monitor activity the other thread information sources cannot.
The following statements are equivalent:
SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST
SHOW FULL PROCESSLIST