![]() ![]() #define LOCK_MAX_DEPTH_IN_DEADLOCK_CHECK 200 * Restricts the recursion depth of the search we will do in the waits-for #define LOCK_MAX_N_STEPS_IN_DEADLOCK_CHECK 1000000 * Restricts the length of search we will do in the waits-for In the innodb source code lock/lock0lock.c file, two constants are defined: Here is a rule for deadlock determination: Purge done for trx's n:o < 695818 undo n:o < 0 state: running but idle TABLE LOCK table `diap_proxy`.`tsp_agt_msg_send` trx id 649212 lock mode AUTO-INC waiting TRANSACTION 649212, ACTIVE 0 sec setting auto-inc lockĤ lock struct(s), heap size 1184, 2 row lock(s) 09:16:01 7f1e2c554700TOO DEEP OR LONG SEARCH IN THE LOCK TABLE WAITS-FOR GRAPH, WE WILL ROLL BACK FOLLOWING TRANSACTION Don't forget to right-click and select all-copy) (When you execute the command in Navicat, you will see that the value of the status column is empty. The deadlock related information viewed using the show engine innodb status command is as follows: ![]() You should include other errors you wish to handle and set $retval depending on whether you'd like to re-execute or continue.As a newbie to MySQL, I was shocked by the deadlock problem I encountered in the project recently, so I quickly wrote down the memo. $retval=0 # we'll check this value and sleep/re-execute if necessary My($message) = m/DBD::mysql::st execute failed: Deadlock found when trying to get lock try restarting transaction/) Print "caught $_ in insertion to hd_item_upc for upc $upc\n" ĭbi_err_handler should have at least the following: sub dbi_err_handler I pass this to a handler function "dbi_err_handler" which checks $_ against a host of errors and returns 1 if the code should continue (thereby breaking the loop) or 0 if its a deadlock and should be retried. The catch block gets $_ which is the specific err message. The below code gives an example where the db code is inside a while loop that will re-execute an errored sql statement every 3 seconds. It seems that rather than going with HandleError, use on Print and Raise and then use something like Try:Tiny to wrap your code and check for errors. The answer is correct, however the perl documentation on how to handle deadlocks is a bit sparse and perhaps confusing with PrintError, RaiseError and HandleError options. Is there a simple way to work around it or lessen its frequency? For example, how exactly do I go about "restarting transaction at Db.pm line 276"? What exactly about my situation is causing the error above? I have seen online that several other people have reported similar errors and that this may be a genuine deadlock situation. MySQL is a standard Solaris deployment, and the database connection is set up as follows: my $dsn = "DBI:mysql:database=". I haven't done much tuning on MySQL or DBD::mysql. The limit is designed to break their work into small chunks. ![]() Note that I am using the a_lock field in file_table to ensure that the four near-identical processes I am running do not try and work on the same row. However, it never happened with a small table and has become more common as the database has grown. The SQL statement that triggers the error is something like this: UPDATE file_table SET a_lock = 'process-1234' WHERE param1 = 'X' AND param2 = 'Y' AND param3 = 'Z' LIMIT 47 One fairly common operation gives rise to the following error sometimes: DBD::mysql::st execute failed: Deadlock found when trying to get lock try restarting transaction at Db.pm line 276. The table has about 10 columns and several indexes. I have a MySQL table with about 5,000,000 rows that are being constantly updated in small ways by parallel Perl processes connecting via DBI. ![]()
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