Node.js服务器循环中的SQL查询

Question

I am trying to set up a server using Node.js. For the database I am using Xampp. I want to run the updateEngine() function when /update is provided. Everything is working , except the code is looping and after a while I get an error. (I used node --max_old_space_size=2000000 )

• Output

   server is up!! connected as id 38 into the query connected as id 39 into the query 

• Error

    69777 ms: Mark-sweep 1398.8 (1456.7) -> 1398.8 (1456.7) MB, 1871.5 / 0 ms [allocation failure] [GC in old space requested]. 71705 ms: Mark-sweep 1398.8 (1456.7) -> 1398.8 (1456.7) MB, 1928.0 / 0 ms [allocation failure] [GC in old space requested]. 73346 ms: Mark-sweep 1398.8 (1456.7) -> 1398.8 (1456.7) MB, 1640.7 / 0 ms [last resort gc]. 75283 ms: Mark-sweep 1398.8 (1456.7) -> 1398.8 (1456.7) MB, 1937.4 / 0 ms [last resort gc]. 

  ==== JS stack trace ======== FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - process out of memory

• Code

   http = require('http'); var connect = require('connect'); var mysql = require('mysql'); var app = connect(); app.use('/update',updateEngine); http.createServer(app).listen(8080); console.log("server is up!!"); function updateEngine(request,response,done) { var connection = mysql.createConnection({ host: 'localhost', port: '3306', user: 'root', password: '', database: 'test' }); connection.connect(function(err) { if (err) { console.error('error connecting: ' + err.stack); return; } console.log('connected as id ' + connection.threadId); }); connection.query('SELECT * FROM `testtable`' , function (error, results, fields) { console.log("into the query"); }); connection.end(); } 

• Xampp

   The MySQL server [mysqld] user = mysql port=3306 socket = /Applications/XAMPP/xamppfiles/var/mysql/mysql.sock skip-external-locking key_buffer = 16M max_allowed_packet = 500M table_open_cache = 64 sort_buffer_size = 512K net_buffer_length = 8K read_buffer_size = 256K read_rnd_buffer_size = 512K myisam_sort_buffer_size = 8M 

Answer 1

Suggestions:

1. Send a response to your requests (even if it's just a simple 200 OK with no body). Right now it's never responding and so the client is probably timing out and automatically retrying the request.

2. Use a database connection pool that you create on startup instead of creating a new database connection for every single request. Using a connection pool is much more efficient since you are not creating and tearing down a connection every time (which adds overhead and latency to your requests).