Lock wait timeout exceeded; try restarting transaction

[Harshdeep Khatri]

Hello All,

I am receving subjected error from mysql following is my mysql infroamtion.

mysql Ver 14.14 Distrib 5.1.54, for debian-linux-gnu (x86_64) using readline 6.1

Everything seems working since long and suddenly today this error was generated on followig query.

UPDATE identity SET lastunkid=:lastunkid WHERE tablename = :tablename AND hotel_code=:hotel_code

this is my own logic to generate custom auto primary key, I have not used any transaction or lock statement for concurrency then also I am seeing intended row was some how get locked (I think it is own innodb row locks not my transaction lock) and my update query start generating errors like this becuase i have default 50 value for innodb_lock_wait_timeout variable.

I have also check the table for corruption it is also showing normal to me.

Please also not that for backup I am using mysqldump without any locks.

Can anyone spot some light and share some information how exactly my row was get locked automatically so other query didn't get access of that row ?