NodeJS - PostgreSQL - Error: timeout exceeded when trying to connect

I write a node script module for using in different pages of my application. this script named "parsDbsPostgres.js". then i write a script for calling and using from "parsDbsPostgres.js", this script named "pg.js". the content of this two file is :

// parsDbsPostgres.js

var pg = require('pg');
var pool;
var config = {
    host: 'localhost',
    port: 5432,
    user: 'postgres',
    password: '123321',
    database: 'trading',
    max: 20,
    idleTimeoutMillis: 10000,
    connectionTimeoutMillis: 2000,
}


function getPool(){
        if (pool){ return pool; } // if it is already there, grab it here
        pool = new pg.Pool(config);
        return pool;
}

function doPgQuery(inputArguments={}, callbackFunction){
    // console.log(inputArguments);
    var outputArguments = {};
    if (Object.prototype.toString.call(inputArguments)!='[object Object]'){
        outputArguments['viReturn'] = false;
        outputArguments['viResult'] = 'INPUT_ARGUMENT_NOT_OBJECT';
        callbackFunction(outputArguments);
    }
    if ('mtPool' in inputArguments) { mtPool = inputArguments['mtPool']; }
    if ('mtSqlQuery' in inputArguments) { mtSqlQuery = inputArguments['mtSqlQuery']; }
    try {
        mtPool.connect(function(err, client, done){
            if(err){
                print(err);
                // done(); // releases connection back to the mtPool
                // print(err);
                outputArguments['viCode'] = 1121;
                outputArguments['viReturn'] = false;
                outputArguments['viMessage'] = 'ERROR_POOL_CONNECT';
                outputArguments['viResult'] = err;
                callbackFunction(outputArguments);
            }
            // if(inputArguments.hasOwnProperty('mtSqlQuery')){
            if(mtSqlQuery){
                client.query(inputArguments.mtSqlQuery, function(err, result){
                    if(err){
                        done();
                        // print(err);
                        outputArguments['viCode'] = 1122;
                        outputArguments['viMessage'] = 'ERROR_CLIENT_QUERY';
                        outputArguments['viSql'] = inputArguments.mtSqlQuery;
                        outputArguments['viReturn'] = false;
                        outputArguments['viResult'] = err;
                        callbackFunction(outputArguments);
                    }else{
                        // var lastInsertID = result.rows[0].id;
                        done();
                        // print(result);
                        outputArguments['viCode'] = 1123;
                        outputArguments['viSql'] = inputArguments.mtSqlQuery;
                        outputArguments['viReturn'] = true;
                        outputArguments['viResult'] = result.rows;
                        // console.log(outputArguments);
                        // console.log(inputArguments.mtSqlQuery);
                        // console.log(mtSqlQuery);
                        // console.log('-------------------------------------------------------------------------------------------------------------\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r');
                        callbackFunction(outputArguments);
                    }
                    // print('Client will end now!!!');
                    // client.end();
                });
            }else{
                done();
                outputArguments['viCode'] = 1124;
                outputArguments['viMessage'] = 'ERROR_HASOWN_PROPERTY_QUERY';
                outputArguments['viReturn'] = false;
                outputArguments['viResult'] = err;
                callbackFunction(outputArguments);
            }

        });
    }catch(e){
        // return {stat:0 , error : e } ;
        console.log(e);
    }
};

module.exports = {
  getPool,
  doPgQuery,
}

// pages.js

var parsDbsPostgres = require('./parsDbsPostgres.js');
const process = require('process');
process.on('beforeExit', (code) => {
  console.log('Process beforeExit event with code: ', code);
});




var start = Date.now();
var counter = 10000000000;
var arrErrors = [];
var nErrors = 0;

function loopCallbackInsert(){

    // var mySqlQuery = 'SELECT id FROM binance_signals WHERE id = 1 ORDER BY id DESC LIMIT 1';
    var mySqlQueryINSERT = 'INSERT INTO binance_signals (id) VALUES(DEFAULT) RETURNING id';

    var ellipsed = (Date.now())-start;
    var newEllipsed = '000000000000'+ellipsed;
    newEllipsed = newEllipsed.substr(newEllipsed.length - 10);

        insertInsertArguments = {
            mtPool: parsDbsPostgres.getPool(),
            mtFieldType: 'float',
            mtSqlQuery: mySqlQueryINSERT,
        }

        parsDbsPostgres.doPgQuery(insertInsertArguments, function(callbackInsertFunction){
            counter++;
            if(!callbackInsertFunction.viReturn){
                nErrors++;
                arrErrors.push(callbackInsertFunction);
            }
            console.log('loopCallbackInsert', nErrors, arrErrors, counter, callbackInsertFunction.viResult);
        });
}



function loopCallbackSelect(){
    var mySqlQuerySelect = 'SELECT id,symbol FROM binance_signals ORDER BY id DESC LIMIT 1';
    // var mySqlQuery = 'INSERT INTO binance_signals (id) VALUES(DEFAULT) RETURNING id';

    var ellipsed = (Date.now())-start;
    var newEllipsed = '000000000000'+ellipsed;
    newEllipsed = newEllipsed.substr(newEllipsed.length - 10);

        insertSelectArguments = {
            mtPool: parsDbsPostgres.getPool(),
            mtFieldType: 'float',
            mtSqlQuery: mySqlQuerySelect,
        }

        parsDbsPostgres.doPgQuery(insertSelectArguments, function(callbackSelectFunction){
            counter++;
            if(!callbackSelectFunction.viReturn){
                nErrors++;
                arrErrors.push(callbackSelectFunction);
            }
            console.log('                                                                      loopCallbackSelect', nErrors, arrErrors, counter, callbackSelectFunction.viResult);
        });

}






process.on('exit', (code) => {
  console.log('----------------------- Process exit event with code: ', code, nErrors, arrErrors, '-------------------------------');
});




try {
        var schedule = require('node-schedule');
        var s = schedule.scheduleJob('* * * * * *', function () { // every 1 second
        for (i = 0; i < 1000; i++){
        loopCallbackSelect();
        loopCallbackInsert();
            }
        });
    }catch(e){
        // return {stat:0 , error : e } ;
        console.log(e);
}

unfortunately sometimes i get error "Error: timeout exceeded when trying to connect". how i can solve this error in this two script. thanks