mysql shutdown and kill

时间：2022-03-10 17:42

--mysqladmin shutdown

If you execute when connecting to a local server using a Unix socket file, waits until the server‘s process ID file has been removed, to ensure that the server has stopped properly.

`KILL` Syntax

KILL [CONNECTION | QUERY] thread_id

Each connection to runs in a separate thread. You can see which threads are running with the statement and kill a thread with the KILL thread_id statement.

permits an optional CONNECTION or QUERY modifier:

is the same as with no modifier: It terminates the connection associated with the giventhread_id.
terminates the statement that the connection is currently executing, but leaves the connection itself intact.

If you have the privilege, you can see all threads. If you have the privilege, you can kill all threads and statements. Otherwise, you can see and kill only your own threads and statements.

You can also use the and commands to examine and kill threads.

Note

You cannot use with the Embedded MySQL Server library because the embedded server merely runs inside the threads of the host application. It does not create any connection threads of its own.

When you use , a thread-specific kill flag is set for the thread. In most cases, it might take some time for the thread to die because the kill flag is checked only at specific intervals:

In , ORDER BY and GROUP BY loops, the flag is checked after reading a block of rows. If the kill flag is set, the statement is aborted.
During , the kill flag is checked before each block of rows are read from the original table. If the kill flag was set, the statement is aborted and the temporary table is deleted.
During or operations, the kill flag is checked after each block read and after each updated or deleted row. If the kill flag is set, the statement is aborted. Note that if you are not using transactions, the changes are not rolled back.
aborts and returns NULL.
An thread quickly flushes (inserts) all rows it has in memory and then terminates.
If the thread is in the table lock handler (state: Locked), the table lock is quickly aborted.
If the thread is waiting for free disk space in a write call, the write is aborted with a “disk full” error message.
Warning

Killing a or operation on a MyISAM table results in a table that is corrupted and unusable. Any reads or writes to such a table fail until you optimize or repair it again (without interruption).