mysql show processlist state

yantaicuiwei發表於2010-12-31

這個命令中最關鍵的就是state列,mysql列出的狀態主要有以下幾種:

  Checking table
 正在檢查資料表(這是自動的)。

 Closing tables
 正在將表中修改的資料重新整理到磁碟中,同時正在關閉已經用完的表。這是一個很快的操作,如果不是這樣的話,就應該確認磁碟空間是否已經滿了或者磁碟是否正處於重負中。

 Connect Out
 複製從伺服器正在連線主伺服器。

 Copying to tmp table on disk
 由於臨時結果集大於tmp_table_size,正在將臨時表從記憶體儲存轉為磁碟儲存以此節省記憶體。

 Creating tmp table
 正在建立臨時表以存放部分查詢結果。

 deleting from main table
 伺服器正在執行多表刪除中的第一部分,剛刪除第一個表。

 deleting from reference tables
 伺服器正在執行多表刪除中的第二部分,正在刪除其他表的記錄。

 Flushing tables
 正在執行FLUSH TABLES,等待其他執行緒關閉資料表。

 Killed
 傳送了一個kill請求給某執行緒,那麼這個執行緒將會檢查kill標誌位,同時會放棄下一個kill請求。MySQL會在每次的主迴圈中檢查kill標誌位,不過有些情況下該執行緒可能會過一小段才能死掉。如果該執行緒程被其他執行緒鎖住了,那麼kill請求會在鎖釋放時馬上生效。

 Locked
 被其他查詢鎖住了。

 Sending data
 正在處理SELECT查詢的記錄,同時正在把結果傳送給客戶端。

 Sorting for group
 正在為GROUP BY做排序。

 Sorting for order
 正在為ORDER BY做排序。

 Opening tables
 這個過程應該會很快,除非受到其他因素的干擾。例如,在執ALTER TABLELOCK TABLE語句行完以前,資料表無法被其他執行緒開啟。正嘗試開啟一個表。

 Removing duplicates
 正在執行一個SELECT DISTINCT方式的查詢,但是MySQL無法在前一個階段最佳化掉那些重複的記錄。因此,MySQL需要再次去掉重複的記錄,然後再把結果傳送給客戶端。

 Reopen table
 獲得了對一個表的鎖,但是必須在表結構修改之後才能獲得這個鎖。已經釋放鎖,關閉資料表,正嘗試重新開啟資料表。

 Repair by sorting
 修復指令正在排序以建立索引。

 Repair with keycache
 修復指令正在利用索引快取一個一個地建立新索引。它會比Repair by sorting慢些。

 Searching rows for update
 正在講符合條件的記錄找出來以備更新。它必須在UPDATE要修改相關的記錄之前就完成了。

 Sleeping
 正在等待客戶端傳送新請求
.
 
System lock
 正在等待取得一個外部的系統鎖。如果當前沒有執行多個mysqld伺服器同時請求同一個表,那麼可以透過增加--skip-external-locking引數來禁止外部系統鎖。

 Upgrading lock
 INSERT DELAYED正在嘗試取得一個鎖表以插入新記錄。

 Updating
 正在搜尋匹配的記錄,並且修改它們。

 User Lock
 正在等待GET_LOCK()

 Waiting for tables
 該執行緒得到通知,資料表結構已經被修改了,需要重新開啟資料表以取得新的結構。然後,為了能的重新開啟資料表,必須等到所有其他執行緒關閉這個表。以下幾種情況下會產生這個通知:FLUSH TABLES tbl_name, ALTER TABLE, RENAME TABLE, REPAIR TABLE, ANALYZE TABLE,OPTIMIZE TABLE

 waiting for handler insert
 INSERT DELAYED已經處理完了所有待處理的插入操作,正在等待新的請求。

 大部分狀態對應很快的操作,只要有一個執行緒保持同一個狀態好幾秒鐘,那麼可能是有問題發生了,需要檢查一下。
 還有其他的狀態沒在上面中列出來,不過它們大部分只是在檢視伺服器是否有存在錯誤是才用得著。

After create

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.

  • Analyzing

    The thread is calculating a MyISAM table key distributions (for example, for ANALYZE TABLE).

  • checking permissions

    The thread is checking whether the server has the required privileges to execute the statement.

  • Checking table

    The thread is performing a table check operation.

  • cleaning up

    The thread has processed one command and is preparing to free memory and reset certain state variables.

  • closing tables

    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.

  • converting HEAP to MyISAM

    The thread is converting an internal temporary table from a MEMORY table to an on-disk MyISAM table.

  • copy to tmp 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.

  • Copying to group table

    If a statement has different ORDER BY and GROUP BY criteria, the rows are sorted by group and copied to a temporary table.

  • Copying to tmp table

    The server is copying to a temporary table in memory.

  • Copying to tmp table on disk

    The server is copying to a temporary table on disk. The temporary result set was larger than tmp_table_size and the thread is changing the temporary table from in-memory to disk-based format to save memory.

  • Creating index

    The thread is processing ALTER TABLE ... ENABLE KEYS for a MyISAM table.

  • Creating sort index

    The thread is processing a SELECT that is resolved using an internal temporary table.

  • creating table

    The thread is creating a table. This includes creation of temporary tables.

  • Creating tmp table

    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.

  • deleting from main table

    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.

  • discard_or_import_tablespace

    The thread is processing an ALTER TABLE ... DISCARD TABLESPACE or ALTER TABLE ... IMPORT TABLESPACE statement.

  • end

    This occurs at the end but before the cleanup of ALTER TABLECREATE VIEWDELETEINSERTSELECT, or UPDATE statements.

  • executing

    The thread has begun executing a statement.

  • Execution of init_command

    The thread is executing statements in the value of the init_command system variable.

  • freeing items

    The thread has executed a command. This state is usually followed by cleaning up.

  • Flushing tables

    The thread is executing FLUSH TABLES and is waiting for all threads to close their tables.

  • FULLTEXT initialization

    The server is preparing to perform. a natural-language full-text search.

  • init

    This occurs before the initialization of ALTER TABLEDELETEINSERTSELECT, or UPDATE statements.

  • Killed

    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.

  • Locked

    The query is locked by another query.

  • logging slow query

    The thread is writing a statement to the slow-query log.

  • NULL

    This state is used for the SHOW PROCESSLIST state.

  • login

    The initial state for a connection thread until the client has been authenticated successfully.

  • Opening tables, Opening table

    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.

  • preparing

    This state occurs during query optimization.

  • Purging old relay logs

    The thread is removing unneeded relay log files.

  • query end

    This state occurs after processing a query but before the freeing items state.

  • Reading from net

    The server is reading a packet from the network.

  • Removing duplicates

    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.

  • removing tmp table

    The thread is removing an internal temporary table after processing a SELECT statement. This state is not used if no temporary table was created.

  • rename

    The thread is renaming a table.

  • rename result table

    The thread is processing an ALTER TABLE statement, has created the new table, and is renaming it to replace the original table.

  • Reopen tables

    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.

  • Repair by sorting

    The repair code is using a sort to create indexes.

  • Repair done

    The thread has completed a multi-threaded repair for a MyISAM table.

  • Repair with keycache

    The repair code is using creating keys one by one through the key cache. This is much slower than Repair by sorting.

  • Rolling back

    The thread is rolling back a transaction.

  • Saving state

    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.

  • Searching rows for update

    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.

  • setup

    The thread is beginning an ALTER TABLE operation.

  • Sorting for group

    The thread is doing a sort to satisfy a GROUP BY.

  • Sorting for order

    The thread is doing a sort to satisfy a ORDER BY.

  • Sorting index

    The thread is sorting index pages for more efficient access during a MyISAM table optimization operation.

  • Sorting result

    For a SELECT statement, this is similar to Creating sort index, but for nontemporary tables.

  • statistics

    The server is calculating statistics to develop a query execution plan.

  • System lock

    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).

  • Table lock

    The next thread state after System lock. The thread has acquired an external lock and is going to request an internal table lock.

  • Updating

    The thread is searching for rows to update and is updating them.

  • updating main table

    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.

  • updating reference tables

    The server is executing the second part of a multiple-table update and updating the matched rows from the other tables.

  • User lock

    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_nameALTER TABLERENAME TABLEREPAIR TABLEANALYZE TABLE, or OPTIMIZE TABLE.

  • Waiting on cond

    A generic state in which the thread is waiting for a condition to become true. No specific state information is available.

  • Writing to net

    The server is writing a packet to the network.

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