標籤：blocking min now() 儲存引擎 服務 who 伺服器 instr query
1.伺服器層級的鎖等待
可以通過show processlist看到等待鎖的線程id，但是無法知道究竟哪個線程持有鎖
可以通過mysqladmin debug
相關等待鎖的線程以及誰持有鎖可以在錯誤記錄檔中找到 #以下是innodb儲存引擎中鎖等待以及哪個線程持有鎖的尋找sql
SELECT r.trx_id AS waiting_trx_id, r.trx_mysql_thread_id AS waiting_thread, TIMESTAMPDIFF(SECOND, r.trx_wait_started, CURRENT_TIMESTAMP) AS wait_time, r.trx_query AS waiting_query, l.lock_table AS waiting_table_lock, b.trx_id AS blocking_trx_id, b.trx_mysql_thread_id AS blocking_thread, SUBSTRING(p.host,1, INSTR(p.host, ‘:‘) -1) AS blocking_host, SUBSTRING(p.host, INSTR(p.host, ‘:‘) +1) AS block_port, IF(p.command="Sleep",p.time,0) AS idle_in_trx, b.trx_query AS blcoking_query
FROM information_schema.innodb_lock_waits AS w
INNER JOIN information_schema.innodb_trx AS b ON b.trx_id=w.blocking_trx_id
INNER JOIN information_schema.innodb_trx AS r ON r.trx_id = w.requesting_trx_id
INNER JOIN information_schema.innodb_locks AS l ON w.requested_lock_id = l.lock_id
LEFT JOIN information_schema.processlist AS p ON p.id = b.trx_mysql_thread_id
ORDER BY wait_time DESC;
#下面查詢顯示儲存引擎層有多少查詢被哪些線程阻塞
SELECT CONCAT(‘thread ‘, b.trx_mysql_thread_id, ‘ from ‘,p.host) AS who_blocks, IF (p.command = "Sleep",p.time, 0) AS idle_in_trx, MAX(TIMESTAMPDIFF(SECOND,r.trx_wait_started, NOW())) AS max_wait_time, COUNT(*) AS num_waiters
FROM information_schema.innodb_lock_waits AS w
INNER JOIN information_schema.innodb_trx AS b ON b.trx_id = w.blocking_trx_id
INNER JOIN information_schema.innodb_trx AS r ON r.trx_id = w.requesting_trx_id
LEFT JOIN information_schema.processlist AS p ON p.id = b.trx_mysql_thread_id
GROUP BY who_blocks
ORDER BY num_waiters DESC;
MySQL找出鎖等待
