sql deadlock

A deadlock occurs when multiple transactions hold and request locks on the same resource at the same time as a result of cyclic dependency. Deadlocks occur when a transaction attempts to lock a resource in a different order. Take the two transactions on the StockPrice table for example: Business 1 START TRANSACTION; UPDATE stockprice SET close = 45.50 WHERE stock_id = 4 and date = ' 2002-05-01 '; UPDATE stockprice SET close = 19.80 WHERE stoc

This article is mainly through an experiment to describe, the process is more boring.Experiment PreparationCREATE TABLE Test_lock (ID int auto_increment PRIMARY key, stock int) Engine=innodb;Insert into Test_lock (id,stock) value (1,50);Here I make the stack information as simple as possible, the names of the 25 main functions and the entry parametersIn order to highlight the topic, I add this to the opening deadlock detection function list, altogeth

Deadlock Reason: To extract the corresponding data of query data and modify the Stat table, all of them modify the same data, carry out large amount of data, and simultaneously, cause database deadlock and block; Related knowledge: 1. SQL deadlock and blocking: http://searchdatabase.techtarget.com.cn/tips/275/2080775.s

Like debugging the lock in userspace, it mainly involves: 1. Locate the lock deadlock and print out the call stack. 2. Find out who is using this mutex. For example, in kernel config, enable is associated with lock/mutex, such as config_debug_mutex and config_detect_hung_tasks. In this way, when a deadlock occurs, wait for a period of time (120 seconds by default). The kernel detects the

First, the concept of deadlock Synchronization of multiple threads can cause deadlocks if they are poorly designed. A deadlock is when multiple threads share certain resources while waiting for the other to release resources, causing the program to stagnate. Deadlock can cause the program to stall, so we must be careful to avoid deadlocks when we write multi-t

 Package test.thread;public class Deadlocktest extends thread{Private Object o;public void SetO (Object o) {This.o=o;}public void Run () {Synchronized (this) {SYSTEM.OUT.PRINTLN ("deadlocktest begin");Synchronized (o) {System.out.println ("Deadlocktest_o");}System.out.println ("Deadlocktest end");}}public static void Main (string[] args) {Deadlocktest dlt=new deadlocktest ();TT tt=new TT (DLT);Dlt.seto (TT);Dlt.start ();Tt.start ();}}Class TT extends thread{Private Object o;Public TT (Object o

PackageCom.swift; Public classDeadLockImplementsRunnable {Private BooleanFlag; DeadLock (Booleanflag) { This. Flag =Flag; } Public voidrun () { while(true) { if(flag) {synchronized("Suo1") {System.out.println (Thread.CurrentThread (). GetName ()+ "If....locka"); synchronized("Suo2") {System.out.println (Thread.CurrentThread (). GetName ()+ "IF.....LOCKB"); } } } Else { synchronized("Suo2"

If there are two locks Lock1 (Mutex_gard mode) and lock;The order of the two calls is different, there will be waiting for each other, resulting in deadlock;To avoid deadlocks, we can:1, each thread lock in the same order of invocation;2, the use of std:: Lock ();In a method called by both the main thread and the child threadStd::lock (Mutex1,mutex2,....);When it's locked.In addition: The mutex itself also has the lock and unlock methodC + + multithre

t1;mysql> insert into t1 values(1,'gao1','gao'),(2,'gao2','gao'),(3,'gao3','gao'),(4,'gao4','gao'),(5,'gao5','gao'),(6,'gao6','gao'),(7,'gao7','gao'),(8,'gao8','gao'); View the execution plan: mysql> desc select * from t1 where n1 in ('gao2','gao3','gao4’)\G*************************** 1. row *************************** id: 1 select_type: SIMPLE table: t1 partitions: NULL type: ALLpossible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 8 filtered: 37.50 Extra:

Tags: bug isolated multiple nod read/write Mutex detection log sharing found that when the SQL statement of the backup table runs at the same time as the SQL statement that deletes part of the data from the table, MySQL detects the deadlock and prints out the log Case descriptionDuring a timed script run, MySQL detects a dead