deadlock prevention

.(3) Conditions of deprivation: the resources that the process has acquired cannot be forcibly deprived of until the end of its use.(4) Cyclic waiting condition: a cyclic waiting resource relationship is formed between several processes.The above four conditions as long as there is a not satisfied, there will be no deadlock.4. Deadlock prevention(1) orderly resou

!!! It is important to analyze the deadlock principle and the deadlock principle. Original Link Author: Desert solitary smokeBackground and Symptom In the online production environment, database operation deadlocks often occur in some cases, and business personnel cannot perform operations. According to DBA analysis, the insert and delete operations on a table are deadlocked. This section briefly introduces

What is a deadlock? If every process in a process set is waiting for an event that can only be triggered by another process in the Set (including itself), this situation is a deadlock. This definition may be a bit confusing. One of the simplest examples is resource A and resource B, which are both uneconomical resources. Now process C has applied for resource, process D also applies for resource B. The nex

MySQL deadlock analysis, mysql deadlock1. Test Description Environment Description: RHEL 6.4 x86_64 + MySQL 5.5.37. The transaction isolation level is RC. Test Table: mysql> show create table t1\G*************************** 1. row *************************** Table: t1Create Table: CREATE TABLE `t1` ( `a` int(11) NOT NULL DEFAULT '0', `b` int(11) DEFAULT NULL, PRIMARY KEY (`a`), KEY `b` (`b`)) ENGINE=InnoDB DEFAULT CHARSET=utf81 row in set (

(reproduced in Breaksoftware's CSDN blog)Previous articles have explained the causes of deadlocks created in DllMain and waiting for threads to cause. Remember, we analyzed the half-day assembly before we knew the deadlock location in the thread. If the lack of debugging experience for students, may find this location a bit troublesome. So this article will introduce a few examples, they will be the obvious location of the thread deadlock.The code in

First, the concept of deadlock:　　1, the phenomenon of deadlock description:　　　　In many applications, a process is required to access several resources, rather than one, in an exclusive way. For example, two processes are prepared to record scanned documents to a CD, respectively. Process a requests that the scanner be used,and is authorized to use. However, Process B first requests a CD burner and is also a

Deadlock analysis 1, the production of deadlocks There is the following code, which simulates the transfer between two accounts void Transfer (account From,account To,int money) { from.setamount (From.getamount ()-money); To.setamount (To.getamount () +money);} Single-threaded, this code is sure to be okay, but there are problems with multithreading Now lock it, lock the code as follows void Transfer (account From,account To,int money) { syn

A deadlock occurs in the program, which causes the w3wp process to restart. This problem is usually difficult to find the cause. I know two instances that may cause this problem. 1. lock or ReaderWriterLock is used in the program, and resource lock contention occurs.Below is a short piece of code: Copy codeThe Code is as follows: // _ rwLock is of the ReaderWriterLock type. _ RwLock. AcquireWriterLock (100 ); DoSomething (); _ RwLock. ReleaseWriterLo

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 line interface can is insecure. First, client

) { WaitForSingleObject (G_hevent, INFINITE); return 0; } BOOL apientry DllMain ( hmodule hmodule, DWORD Ul_reason_for_call, lpvoid lpreserved ) { switch (ul_reason_for_call) { Case Dll_process_attach: { G_hevent =:: CreateEvent (NULL, FALSE, FALSE, NULL); G_thread_handle =:: CreateThread (NULL, 0, threadcreateindllmain,null, 0, NULL); } break; Case Dll_process_detach: { :: SetEvent (G_hevent); :: WaitForSingleObject (G_thread_handle, INFINITE);

effective in preventing deadlocks, but it may reduce the utilization of system resources.(2) Avoid deadlockBecause on the one hand, the method of preventing deadlock will reduce the utilization of system resources, on the other hand, the necessary condition of deadlock is the existence of the system will cause deadlock, so in order to improve the utilization of

resources obtained by the process cannot be forcibly deprived before they are used.(4) Cyclic waiting condition: a cyclic waiting resource relationship is formed between several processes that are connected at the beginning and end. These four conditions are necessary for a deadlock. As long as a deadlock occurs in the system, these conditions must be met. As long as one of the above conditions is not met,

request for the lock is discarded and the lock is freed) Deadlock detection Lock OrderDeadlocks can easily occur when multiple threads require the same locks, but are locked in different order.If you can ensure that all threads are getting locks in the same order, the deadlock does not occur. Look at the following example:Thread 1: lock A lock Bthread 2: wait for a lock C (when a locked) th

release the obtained resources.(3) non-deprivation condition: the resources obtained by the process cannot be forcibly deprived before they are used.(4) cyclic waiting condition: a cyclic waiting resource relationship is formed between several processes that are connected at the beginning and end. These four conditions are necessary for a deadlock. as long as a deadlock occurs in the system, these conditio

obtained resources.(3) non-deprivation condition: the resources obtained by the process cannot be forcibly deprived before they are used.(4) cyclic waiting condition: a cyclic waiting resource relationship is formed between several processes that are connected at the beginning and end. These four conditions are necessary for a deadlock. as long as a deadlock occurs in the system, these conditions must be m

, the deadlock is inevitable. Resource allocation chart: to clearly check whether a deadlock exists. P-> r real-line application; r-> P real-line allocation; P-> r dotted-line requirement.When each resource type has only one instance, a loop is equivalent to a deadlock.If there are multiple instances in the resource type, the deadlock must be a loop, and 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"

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