Note: The transaction (Process ID 56) is deadlocked with another process in the lock | The communication buffer resource and has been selected as the deadlock victim.

An exception was encountered today when doing SQL Concurrency update: (Code below)

// Parallel class can produce concurrent operations (i.e. multithreading) Parallel.ForEach (topics, topic ={    //DBHelper is a encapsulated database operation class, the following line of code executes the UPDATE statement    "topicid=" + topic. TOPICID);});

This problem occurs because, in SQL Server by default, an SQL statement is a transaction. When multi-threaded simultaneous update, it will produce multiple transactions at the same time, a transaction waits for the end of B transaction, b transaction waits for a transaction to end, then causes the deadlock.

Workaround: Lock locking (that is, when multiple threads access the lock code area at the same time, only one thread is allowed to enter, and the other threads are in a wait state)

 //  declares a static read-only lock object   static  readonly  object  o = new  object  (); Parallel.ForEach (topics, topic  =>{ / /  lock  lock   (o) { //  Only one thread at a time can enter  Dbhelper.update (topic,  " topicid=   " + topic.    TOPICID); }});

Small note: The transaction (Process ID 56) is deadlocked with another process on the lock | Communication buffer resource and has been selected as the deadlock victim.