无法在Node.js脚本中关闭postgreSQL连接

Question

我正在编写小node.js服务器来帮助维护构建机器.它基本上适用于测试人员能够远程丢弃数据库或重启服务器.我有一些关于pg连接的问题.任何人都可以知道为什么在第一次请求后没有关闭它？

var client = new pg.Client(conString);

var server = http.createServer(function (req, res) {
var url = parse(req.url);

if (url.pathname =='/'){
    (...)
}else{
     var slash_index = url.pathname.indexOf('/',1);
     var command = url.pathname.slice(1,slash_index);

     if (command =='restart'){
        res.write('restarting server please wait');
     } else if (command == 'drop-db'){

     console.log('drop-db');
     client.connect();
     console.log('connect');
     var query = client.query("select datname from pg_database;", function(err, result) {
        if (err) throw err;
        console.log('callback');
        });

     query.on('end', function() {
             console.log('close');
             client.end();
             });

} else{
  res.write('unknown command : '+ command);
}
res.write('\n');
res.end();
}


}).listen(5337);

所以我在第一次请求后在屏幕上看到的是:

drop-db
connect
callback
close

很棒但是在接下来的请求后我才会得到

drop-db
connect

在下一个之后我已经得到了一个pg错误

我做错了什么？

编辑:第二次提交后没有错误.第三次出错:

events.js:48
    throw arguments[1]; // Unhandled 'error' event
                   ^
error: invalid frontend message type 0
    at [object Object].<anonymous> (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:412:11)
    at [object Object].parseMessage (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:287:17)
    at Socket.<anonymous> (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:45:22)
    at Socket.emit (events.js:88:20)
    at TCP.onread (net.js:347:14)

我认为这与旧的仍然开启时打开新连接有关.

编辑2:

我查了postgres日志:

第二次请求后:

 2012-03-13 09:23:22 EET LOG:  invalid length of startup packet

第三次请求后:

 2012-03-13 09:24:48 EET FATAL:  invalid frontend message type 0

Answer 1

看起来客户端(pg.Client)声明在请求范围之外,这可能是您的问题.从代码片段中很难说,但看起来您可能会遇到范围问题以及异步回调控制流如何工作,例如在回调仍在IO队列中时调用res.end().这对节点来说是完全合法的,只是不确定这是你的意图.

最好使用返回客户端的pg.connect.请参阅https://github.com/brianc/node-postgres/wiki/pg

var pg = require('pg');

var server = http.createServer(function (req, res) {
  var url = parse(req.url);

  if (url.pathname =='/'){
      (...)
  }else{
       var slash_index = url.pathname.indexOf('/',1);
       var command = url.pathname.slice(1,slash_index);

       if (command =='restart'){
          res.write('restarting server please wait');
       } else if (command == 'drop-db'){

       console.log('drop-db');
       pg.connect(conString, function(err, client) {
         console.log('connect');
         var query = client.query("select datname from pg_database;", function(err, result) {
            if (err) throw err;
            console.log('callback');
            });

         query.on('end', function() {
                 console.log('close');
                 // client.end(); -- not needed, client will return to the pool on drain
                 });

       });

  } else{
    res.write('unknown command : '+ command);
  }
  // these shouldn't be here either if you plan to write to res from within the pg 
  // callback
  res.write('\n');
  res.end();
}


}).listen(5337);