Connection timed out when using connection pooling - mysql

Question

I get the following error when I get a connection object from a connection pool. It works sometimes but sometimes I get an error and the connection is undefined. I don't think I am supposed to get a connection timeout error because I'm using connection pool and in a connection pool you already have a few connections and you're not creating a new connection.
Can someone tell me how to handle this error and connect again.
The error at getConnection
{ [Error: connect ETIMEDOUT]
errorno: 'ETIMEDOUT',
code: 'ETIMEDOUT',
syscall: 'connect',
fatal: true }
The code:
var pool = mysql.createPool({
connectionLimit : 100, //important
host : '192.168.2.2',
user : 'testmysql',
password : 'test123',
database : 'tollsystem',
debug : false
});
I get the error here while using the pooled object:
app.get('/getClientList',function(req,res){
var data={
"error":1,
"clients":""
};
pool.getConnection(function(err,connection){
console.log(err);
connection.query("select * from mstrclient",function(err,rows,fields){
if(rows.length !=0){
res.json(rows);
}else{
data["error"]=1;
data["clients"]="no details found";
res.json(data);
}
connection.release();
})
});
});
The error:
connection.query("select * from mstrclient",function(err,rows,fields){
^
TypeError: Cannot read property 'query' of undefined
at D:\abhilash\Projects\Toll main aHosted\TollMain\server.js:415:15
at Handshake.onConnect (D:\abhilash\Projects\Toll main aHosted\TollMain\node
_modules\mysql\lib\Pool.js:58:9)
at Handshake.Sequence.end (D:\abhilash\Projects\Toll main aHosted\TollMain\n
ode_modules\mysql\lib\protocol\sequences\Sequence.js:85:24)
at D:\abhilash\Projects\Toll main aHosted\TollMain\node_modules\mysql\lib\pr
otocol\Protocol.js:399:18
at Array.forEach (native)
at D:\abhilash\Projects\Toll main aHosted\TollMain\node_modules\mysql\lib\pr
otocol\Protocol.js:398:13
at nextTickCallbackWith0Args (node.js:420:9)
at process._tickCallback (node.js:349:13)