NodeJS + MySQL:使用连接池导致死锁表 [英] NodeJS + mysql: using connection pool leads to deadlock tables

问题描述

我正在使用NodeJS和mysql库访问MySQL数据库.

I am using NodeJS and mysql library to access MySQL database.

当我建立单个连接并重复使用它时，它可以正常工作:

When I establish single connection and repeatedly use it, it works fine:

global.mysql = mysql_module.createConnection({

        host: config.mysql.host,
        user: config.mysql.user,
        password: config.mysql.password
    });

当我改用连接池时，在事务中出现ER_LOCK_WAIT_TIMEOUT错误.

When I use connection pool instead, I get ER_LOCK_WAIT_TIMEOUT errors in transactions.

global.mysql = mysql_module.createPool({

        host: config.mysql.host,
        user: config.mysql.user,
        password: config.mysql.password,
        database : config.mysql.database,
        connectionLimit : 50
    });

奇怪的是，错误确实在完全相同的时间发生在完全相同的数据上. IE.我有一个事务，我在其中连续插入三个表中，每次都使用上一个INSERT语句中的最后插入的ID.对于某些数据，这可以正常工作；对于某些数据，第三个INSERT会产生ER_LOCK_WAIT_TIMEOUT错误.当我在NodeJS中使用单个连接时，这可以正常工作，因此这一定是与连接池有关的问题.

Strangely enough, the errors do occur on exactly the same data at exactly the same times. I.e. I have transaction in which I insert in three tables in a row, each time using last inserted ID from previous INSERT statement. With some data this works fine, with some data, the third INSERT produces ER_LOCK_WAIT_TIMEOUT error. When I use single connection in NodeJS, this works fine, so this must be problem related to connection pool.

任何帮助将不胜感激.

推荐答案

不支持我自己的问题，但是可以通过在池中显式创建连接并将该连接用于事务期间的每个sql语句来解决问题.

No a big fan of asnwering my own questions, but problem is solved by explicitly creating connection from a pool and using it for every sql statement during transaction

pool.getConnection(function(err, connection) {
  connection.query( 'START TRANSACTION', function(err, rows) {
    // do all sql statements with connection and then
    connection.query( 'COMMIT', function(err, rows) {
       connection.release();
    }       
  });
});

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