node.js - request - How to “emitter.setMaxListener

问题:

When I do a GET on a certain URI using the node.js 'request' module;

var options = {uri:"aURI", headers:headerData};
request.get(options, function (error, response, body) {
}

The error message is:

[Error: Exceeded maxRedirects. Probably stuck in a redirect loop.]

and there is also the following message:

"(node) warning: possible EventEmitter memory leak detected. 11 listeners added. Use emitter.setMaxListeners() to increase limit."

How do I setMaxListeners?

回答1:

I use the code to increase the default limit globally: require('events').EventEmitter.prototype._maxListeners = 100;

回答2:

I strongly advice NOT to use the code:

process.setMaxListeners(0);

The warning is not there without reason. Most of the time, it is because there is an error hidden in your code. Removing the limit removes the warning, but not its cause, and prevents you from being warned of a source of resource leakage.

If you hit the limit for a legitimate reason, put a reasonable value in the function (the default is 10).

Also, to change the default, it is not necessary to mess with the EventEmitter prototype. you can set the value of defaultMaxListeners attribute like so:

require('events').EventEmitter.defaultMaxListeners = 15;

回答3:

Although adding something to nodejs module is possible, it seems to be not the best way (if you try to run your code on other computer, the program will crash with the same error, obviously).

I would rather set max listeners number in your own code:

var options = {uri:headingUri, headers:headerData, maxRedirects:100};
request.setMaxListeners(0);
request.get(options, function (error, response, body) {
}

回答4:

This is how I solved the problem:

In main.js of the 'request' module I added one line:

Request.prototype.request = function () {
  var self = this
  self.setMaxListeners(0); // Added line

This defines unlimited listeners http://nodejs.org/docs/v0.4.7/api/events.html#emitter.setMaxListeners

In my code I set the 'maxRedirects' value explicitly:

var options = {uri:headingUri, headers:headerData, maxRedirects:100};