我有连接到mongoDB的node.js文件并获取集合中的文档数量然后它在for循环中运行并使用我从外部服务器获取的值更新每个文档是我一次打开很多连接并且程序崩溃，我的问题是如何一次使用 1个连接和多个连接这是我的代码：
var request = require('request');
var cheerio = require ('cheerio');
var fs = require('fs');
var MongoClient = require('mongodb').MongoClient;
//var config = JSON.parse(fs.readFileSync("config.json"));
//var host = config.host;
//var port = config.port;
// Variable Deceleration
//var dbName = "ystocks";
var port = "27017";
var host = "localhost";
var collection = "stocks"
var dbName = "yahooStocks";
function updateStock(){
// getting the number of docs in the collection
getNumOfDocs("stocks", host, port, dbName, function(err, count) {
if (err) {
return console.log(err.message);
}
console.log('number of documents', count);
for(i = 0 ; i <= 20; i++)
{
// Finding each document by _id with a callbak
GetDocumentByID("stocks", host, port, dbName, i, function(err, findOne) {
if (err) {
return console.log(err.message);
}
console.log('Here is the doc that was found', findOne.ticker);
var stockName = findOne.ticker;
console.log("\n* stock name : " +stockName + "\n");
var yUrl = "http://finance.yahoo.com/q/ks?s=" + stockName;
getStockValue(stockName, yUrl);
}); // end of GetDocumentByID
}//end of for loop
}); // end of getNumOfDocs call
}// end of update function
////passed arguments
//stockName = for printing stock name to console
//yUrl = the specific url for the current stock ticker
function getStockValue(stockName, yUrl){
request(yUrl, stockName, function (error, response, body) {
var date = setTimeToLocal(new Date(), 3);
if (!error && response.statusCode == 200) {
var $ = cheerio.load(body);
// the keys - We get them from a certain class attribute
var span = $('.time_rtq_ticker>span');
var stockValue = $(span).text();
console.log("checking the type of the stockValue " + typeof(stockValue));
//*************************************
// parsing the value to int in case it was a String
var parsedValue = parseFloat(stockValue);
console.log("checking the type of the stockValue " + typeof(parsedValue) + " " + parsedValue);
// Calling the setStockValue function which will update the stock value
setStockValue(stockName, parsedValue);
//writehead ???
//response.writeHead(200, {'Content-Type':'text/plain'});
console.log("Response received from -> " + yUrl);
console.log(date);
console.log("Stock - " + stockName + " --> " + stockValue );
//response.write is for printing in browser when we have a server running
//response.write("Welcome to stockwatch\n");
//response.write("Stock - " + ticker + " current value--> " + stockValue + "\n" );
//TODO #1
//ALEX : lines 61-72 -> should be replaced with a function call that
// connects to the DB and updates the specified stock
//i think it sould look like this : funcName( tickerName , currenValue ){...}
var json = {stockName : "", price : "", date : ""};
json.price = stockValue;
json.stockName = stockName;
json.date = date;
var tempName = json.stockName +'.json';
fs.writeFile( tempName ,JSON.stringify(json, null, 4) , function(err) {
if(!err) {
console.log("File successfully written");
}
});//end of filewrite
//end of TODO #1
//response.end("res end");
}//end of !error && response.statusCode == 200
else if (response.statusCode == 404){
console.log("Response failed from " + yUrl + " --> error code: " + response.statusCode);
}//end of statusCode == 400
});// end of request
}//end of getStockValue
// updating a stock with a provided ticker and value and the MongoClient
// edited by Alex Brodov on : AUG 21 2014
function setStockValue(ticker, value) {
// open the connection the DB server
MongoClient.connect("mongodb://localhost:27017/yahooStocks", function (error, db){
if(error) throw error;
var query = {'ticker' : ticker};
operator ={'$set' : {'value' : value}};
// find one document in our collection
db.collection('stocks').update(query, operator, function(error, updated){
if (error) throw error;
//print the result
console.dir("Successfully updated " + updated + " document");
// close the DB
db.close();
});// end of update
}); // Connection to the DB
} // end of setStockValue
// Gets the local date and the desired offset time
// set
function setTimeToLocal(date, offset ) {
// getting the local tome in millseconds
var localtime = date.getTime();
// getting the local offset in millseconds
var localOffset = date.getTimezoneOffset()*60000;
var utc = localOffset + localtime;
// Jerusalem offset
// var offset = 3;
// Jerusalem time in millseconds
var jerusalem = utc + (offset*3600000);
var d = new Date(jerusalem);
console.log("Jerusalem Local Time: " + d.toLocaleString());
return d;
} // end of SetTimeToLocal
/**
* Gets the number of documents from a collection
* With a provided collection name, DB host, DB port, DB name and a callback function
* Edited by Alex
*/
function getNumOfDocs (collectionName, host, port, dbName, callback) {
var mongoConnection = MongoClient.connect("mongodb://" + host + ":" + port + "/" + dbName, function (error, db){
if(error) return callback(err);
db.collection(collectionName).count({}, function(error, numOfDocs){
if(error) return callback(err);
db.close();
callback(null, numOfDocs);
}); // end of count
}); // end of connection to DB
} // end of getNumOfDocs
/**
* Gets a document
* With a provided collection name, DB host, DB port, DB name, the document ID and a callback
* Edited by Alex Brodov on Aug 24th 2014
*/
function GetDocumentByID (collectionName, host, port, dbName, docID, callback) {
// open the connection to DB server
MongoClient.connect("mongodb://" + host + ":" + port + "/" + dbName, function (error, db){
if(error) return callback(error);
var query = {'_id' : docID};
// find one document in our collection
db.collection(collectionName).findOne(query, function(error, doc) {
if (error) return callback(error);
console.log(doc);
// close the DB
db.close();
callback(null, doc);
});// end of findOne
}); // Connection to the DB
}
var refreshInterval = setInterval(updateStock, 30000);
答案 0 :(得分：2)
在MongoDB / Node应用程序中，您应该在启动时执行一次MongoClient.connect（），然后根据需要直接重用db对象。 MongoClient实际上是一个连接池并且效率很高。
所以你应该检查你的代码，只连接一次，它应该解决问题（更快的程序和更少的连接）
从程序中删除所有mongoclientconnect，callback和db.close
他们添加了以下“围绕您的代码”
MongoClient.connect("mongodb://localhost:27017/yahooStocks", function (error, db){ if(error) throw error; // all your methods here // ... // .. var refreshInterval = setInterval(updateStock, 3000); });