mysql deadlock

=4 for update;Normal non-blocking! Summarize:It is clear from the above test that MySQL is associated with the update, just as the table of the association query if there is no corresponding index will be the row data that satisfies the condition of the lock operation, in the T1 table for data query when the id=4 condition of all data will be added S lock, and T2 Table Association to judge the data and do update the corresponding line reque

remains in the same state for several seconds, a problem may occur and need to be checked. There are other states that are not listed above, but most of them are only useful to see if there is an error in the server.2 show full processlist;Show Processlist; only the first 100 are listed, please use show full processlist if you want to list them all.3 Show open tables;This command is able to see which tables are currently open. The In_use column indicates how many threads are using a table, name

, to see the value of the next autocommit.Mysql> SELECT @ @autocommit;-------------------------------------| @ @autocommit |-------------------------------------| 0 |-------------------------------------1 row in Set (0.00 sec)Mysql>See shiny 0, this setting causes the original UPDATE statement if there is no commit, you re-execute the UPDATE statement, you will wait for the lock, when the waiting time is too long, will be reported error 1205 (HY000):

Dead lockexists in row level lockConditions of existence1. Resources can only be occupied by one thread at a time2. Resource possession cannot be forcibly deprived3. Request and maintain possession (to maintain the possession of existing resources while requesting possession of resources)4, the death cycle (generally do the program of the people most concerned about the point)One to three points is MySQL InnoDB all the features, only four is what we c

lock information is as follows: Thread 5 is waiting for a lock authorization during the insert operation and has waited for 10 seconds. We can see that transaction 0 10248 holds 2 locks; transaction 0 10247 has 2 locks and 1 waits for Lock authorization. The entire database only has these two transactions, so the insert wait lock must be held by 0 10248. If the insert Statement of T2 continues to be executed, the deadlock will occur. The

14.5.5.1 an InnoDB deadlock Example a InnoDB deadlock instance the following example demonstrates an error that can occur when a lock request causes a deadlock, example design 2 clients, A and b:jekins:/root# MySQL -uroot-p1234567-e "show ENGINE INNODB status\g;" | Grep-i dead warning:using A password on the command l

Deadlock A deadlock occurs when multiple threads are blocked at the same time, and one or all of them are waiting for the release of a resource. The program cannot be terminated because the thread is blocked indefinitely. The root cause of the deadlock is the improper use of the "synchronized" keyword to manage the access of a thread to a specific object. The key

Analyze the conditions and causes of deadlock in detail, and analyze the deadlock Conditions I. Definition Deadlock: every process in the set is waiting for events that can only be triggered by other processes in the set, so the process in this group is deadlocked. Because resource usage is mutually exclusive, after a process applies for resources, the relevant p

Today to see the group in the discussion of the database deadlock problem, also studied the next, check out some of the information summarized here.The so-called deadlock: Refers to two or more than two processes in the course of execution, because of the competition for resources caused by a mutual waiting phenomenon, if there is no external force, they will not be able to proceed. At this point the system

Deadlock ExampleMulti-threading often encounter deadlock problems, learning the operating system will talk about the deadlock related things, we use Python visual demonstration. One reason for a deadlock is a mutex. Assuming a banking system, user A tries to transfer 100 dollars to User B, while User B tries to transfe

Database deadlock and resolving deadlock problemsdeadlocks (Dead lock )The so-called deadlock The main causes of deadlocks are: (1) due to insufficient system resources. (2) The sequence of progress of the process is not appropriate. (3) Improper allocation of resources and so on.If the system has sufficient resources, the resource requests of the process can be

14.5.5.2 deadlock detection and Rollback deadlock detection and rollback InnoDB automatic transaction deadlock and rollback a transaction InnoDB try to pick a small transaction to roll back and forth, the size of the transaction is Rows inserted, updated, or deleted the number of determined InnoDB know the table lock if Innodb_table_locks = 1 (the default) a

Root Cause and solution of MSSQL deadlock, root cause of mssql deadlock 1. What is deadlock? A deadlock occurs when two or more processes compete for resources during execution. Without external force, they cannot be pushed forward. at this time, it is said that the system is in a