The following list describes thread State
values that are associated with general query processing and
not more specialized activities such as replication. Many of
these are useful only for finding bugs in the server.
This occurs when the thread creates a table (including internal temporary tables), at the end of the function that creates the table. This state is used even if the table could not be created due to some error.
The thread is calculating a MyISAM
table key distributions (for example, for
ANALYZE TABLE
).
The thread is checking whether the server has the required privileges to execute the statement.
The thread is performing a table check operation.
The thread has processed one command and is preparing to free memory and reset certain state variables.
The thread is flushing the changed table data to disk and closing the used tables. This should be a fast operation. If not, you should verify that you do not have a full disk and that the disk is not in very heavy use.
The thread is converting an internal temporary table from
a MEMORY
table to an on-disk
MyISAM
table.
The thread is processing an ALTER
TABLE
statement. This state occurs after the
table with the new structure has been created but before
rows are copied into it.
If a statement has different ORDER BY
and GROUP BY
criteria, the rows are
sorted by group and copied to a temporary table.
The server is copying to a temporary table in memory.
The server is copying to a temporary table on disk. The temporary result set has become too large (see Section 7.5.10, “How MySQL Uses Internal Temporary Tables”). Consequently, the thread is changing the temporary table from in-memory to disk-based format to save memory.
The thread is processing ALTER TABLE ... ENABLE
KEYS
for a MyISAM
table.
The thread is processing a
SELECT
that is resolved
using an internal temporary table.
The thread is creating a table. This includes creation of temporary tables.
The thread is creating a temporary table in memory or on
disk. If the table is created in memory but later is
converted to an on-disk table, the state during that
operation will be Copying to tmp table on
disk
.
The server is executing the first part of a multiple-table delete. It is deleting only from the first table, and saving columns and offsets to be used for deleting from the other (reference) tables.
deleting from reference tables
The server is executing the second part of a multiple-table delete and deleting the matched rows from the other tables.
The thread is processing an ALTER TABLE ...
DISCARD TABLESPACE
or ALTER TABLE ...
IMPORT TABLESPACE
statement.
This occurs at the end but before the cleanup of
ALTER TABLE
,
CREATE VIEW
,
DELETE
,
INSERT
,
SELECT
, or
UPDATE
statements.
The thread has begun executing a statement.
The thread is executing statements in the value of the
init_command
system variable.
The thread has executed a command. This state is usually
followed by cleaning up
.
The thread is executing
FLUSH
TABLES
and is waiting for all threads to close
their tables.
The server is preparing to perform a natural-language full-text search.
This occurs before the initialization of
ALTER TABLE
,
DELETE
,
INSERT
,
SELECT
, or
UPDATE
statements. Actions
taken by the server in this state include flushing the
binary log, the InnoDB
log, and some
query cache cleanup operations.
Someone has sent a KILL
statement to the thread and it should abort next time it
checks the kill flag. The flag is checked in each major
loop in MySQL, but in some cases it might still take a
short time for the thread to die. If the thread is locked
by some other thread, the kill takes effect as soon as the
other thread releases its lock.
The query is locked by another query.
The thread is writing a statement to the slow-query log.
This state is used for the SHOW
PROCESSLIST
state.
The initial state for a connection thread until the client has been authenticated successfully.
The thread is trying to open a table. This is should be
very fast procedure, unless something prevents opening.
For example, an ALTER TABLE
or a LOCK
TABLE
statement can prevent opening a table
until the statement is finished.
This state occurs during query optimization.
The thread is removing unneeded relay log files.
This state occurs after processing a query but before the
freeing items
state.
The server is reading a packet from the network.
The query was using
SELECT
DISTINCT
in such a way that MySQL could not
optimize away the distinct operation at an early stage.
Because of this, MySQL requires an extra stage to remove
all duplicated rows before sending the result to the
client.
The thread is removing an internal temporary table after
processing a SELECT
statement. This state is not used if no temporary table
was created.
The thread is renaming a table.
The thread is processing an ALTER
TABLE
statement, has created the new table, and
is renaming it to replace the original table.
The thread got a lock for the table, but noticed after getting the lock that the underlying table structure changed. It has freed the lock, closed the table, and is trying to reopen it.
The repair code is using a sort to create indexes.
The thread has completed a multi-threaded repair for a
MyISAM
table.
The repair code is using creating keys one by one through
the key cache. This is much slower than Repair by
sorting
.
The thread is rolling back a transaction.
For MyISAM
table operations such as
repair or analysis, the thread is saving the new table
state to the .MYI
file header. State
includes information such as number of rows, the
AUTO_INCREMENT
counter, and key
distributions.
The thread is doing a first phase to find all matching
rows before updating them. This has to be done if the
UPDATE
is changing the
index that is used to find the involved rows.
Sending data
The thread is processing rows for a
SELECT
statement and also
is sending data to the client.
The thread is beginning an ALTER
TABLE
operation.
The thread is doing a sort to satisfy a GROUP
BY
.
The thread is doing a sort to satisfy a ORDER
BY
.
The thread is sorting index pages for more efficient
access during a MyISAM
table
optimization operation.
For a SELECT
statement,
this is similar to Creating sort index
,
but for nontemporary tables.
The server is calculating statistics to develop a query execution plan. If a thread is in this state for a long time, the server is probably disk-bound performing other work.
The thread is going to request or is waiting for an
internal or external system lock for the table. If this
state is being caused by requests for external locks and
you are not using multiple mysqld
servers that are accessing the same tables, you can
disable external system locks with the
--skip-external-locking
option. However, external locking is disabled by default,
so it is likely that this option will have no effect. For
SHOW PROFILE
, this state
means the thread is requesting the lock (not waiting for
it).
The next thread state after System
lock
. The thread has acquired an external lock
and is going to request an internal table lock.
The thread is searching for rows to update and is updating them.
The server is executing the first part of a multiple-table update. It is updating only the first table, and saving columns and offsets to be used for updating the other (reference) tables.
The server is executing the second part of a multiple-table update and updating the matched rows from the other tables.
The thread is going to request or is waiting for an
advisory lock requested with a
GET_LOCK()
call. For
SHOW PROFILE
, this state
means the thread is requesting the lock (not waiting for
it).
Waiting for tables
, Waiting
for table
The thread got a notification that the underlying structure for a table has changed and it needs to reopen the table to get the new structure. However, to reopen the table, it must wait until all other threads have closed the table in question.
This notification takes place if another thread has used
FLUSH
TABLES
or one of the following statements on the
table in question: FLUSH TABLES
,
tbl_name
ALTER TABLE
,
RENAME TABLE
,
REPAIR TABLE
,
ANALYZE TABLE
, or
OPTIMIZE TABLE
.
Waiting for release of readlock
The thread is waiting for a global read lock obtained by
another thread (with
FLUSH TABLES WITH
READ LOCK
) to be released.
A generic state in which the thread is waiting for a condition to become true. No specific state information is available.
The thread has issued a
FLUSH TABLES WITH
READ LOCK
statement to obtain a global read lock
and is waiting to obtain the lock.
The server is writing a packet to the network.
User Comments
"Waiting for table" can also happen on TRUNCATE TABLE
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