ConnectionPool.release Exception in node js while accessing DB using mssql

[chris joe]

Node.js version: v4.2.6

OS: Linux

Sql server: 2012

I have used node js to connect mssql database server. Data's are inserted into DB continuously 

But we are facing connection pool release exception sometimes.

Find the code snippet and issue in below 

 Code:

    var sql = require('mssql')
    var dbconfig = {
        server: 'xxxx',
        database: 'xxxx',
        user: 'xxx',
        password: 'xxx',
        port: 'xx'
    };
    try {
        sql.close();
        var connection = sql.connect(dbconfig, function (err) {
   
            if (err) console.log(err);
   
            var sqlquery = '';
            var request = new sql.Request();
            //query to the database and get the repo value
            sqlquery = 'select Repo from verylargetable';
            request.query(sqlquery, function (err, result) {
                if (err) console.log(err)
                var repo = result.recordset[0].Repo;
   
                //query to the database and get the commit value
                sqlquery = "select Commit from verylargetable where Repo='" + repo + "'";
                request.query(sqlquery, function (err, result) {
                    if (err) console.log(err)
                    var comm = result.recordset[0].Commit;
   
                    //query to the database and update the table
                    sqlquery = "UPDATE verylargetable set Repo='" + repo + "', WHERE Comm='" + comm + "'";
                    request.query(sqlquery, function (err, result) {
                        if (err) console.log(err)
                        console.log("record(s) updated");
                    });
                });
            });
        });
    }
    catch (e) {
        console.log("===========Exception Occurred==========");
        console.log(e);
        console.log(new Date().toString());
        console.log("==========================================================");
    }

Issue:

    

 TypeError: Cannot read property 'release' of null
 at ConnectionPool.release (/usr/lib/Webhook/node_modules/mssql/lib/base.js:199:14)
 at Request.userCallback (/usr/lib/Webhook/node_modules/mssql/lib/tedious.js:608:25)
 at Request._this.callback (/usr/lib/Webhook/node_modules/tedious/lib/request.js:47:27)
 at Connection.message (/usr/lib/Webhook/node_modules/tedious/lib/connection.js:1401:27)
 at Connection.dispatchEvent (/usr/lib/Webhook/node_modules/tedious/lib/connection.js:687:45)
 at MessageIO.<anonymous> (/usr/lib/Webhook/node_modules/tedious/lib/connection.js:602:18)
 at emitNone (events.js:67:13)
 at MessageIO.emit (events.js:166:7)
 at ReadablePacketStream.<anonymous> (/usr/lib/EJ2Webhook/node_modules/tedious/lib/message-io.js:102:16)
 at emitOne (events.js:77:13)
 at ReadablePacketStream.emit (events.js:169:7)

How to resolve this exception and how to handle exception in query execution?

[Tony Mobily]

Hi,

This looks like a problem with the mssql module itself.

There is already an open bug: https://github.com/patriksimek/node-mssql/issues/467

I would watch that bug and see if you can find any hints!

Merc.

[Tony Mobily]

Hi,

Ah, I just noticed YOU are the poster of that bug!

Merc.

On Thursday, 7 December 2017 12:36:44 UTC+8, christopher wrote: