(node) warning: possible EventEmitter memory leak detected. 11 listeners added.

[ymettier]

Hello,

I'm using perfmon node module and when I run my js with node --debug, I get an error message starting like this :

$ node --debug --harmony myscript.js
debugger listening on port 5858
(node) warning: possible EventEmitter memory leak detected. 11 listeners added. Use emitter.setMaxListeners() to increase limit.
Trace
    at TypePerf.addListener (events.js:160:15)
    at PerfmonStream.attach (c:\myproject\node_modules\perfmon\lib\PerfmonStream.js:19:11)
[...]

Important note : I call many times perfmon("\\some perf\counter", ...) and that's why I probably need more than 10 listeners.

A short hack is to use setMaxListeners(0) (no limit) like this :

diff --git a/node_modules/perfmon/lib/TypePerf.js b/node_modules/perfmon/lib/TypePerf.js
index a8db4eb..8437c81 100755
--- a/node_modules/perfmon/lib/TypePerf.js
+++ b/node_modules/perfmon/lib/TypePerf.js
@@ -5,6 +5,7 @@ var os = require('os');

 function TypePerf(host, counters) {
        Stream.call(this);
+       this.setMaxListeners(0);

        this.host = host;
        this.cp = [];

Is that a good hack ?

• no because having a limit helps the developer notice memory leaks
• yes because in that specific case, the developer (like me) may need more listeners than the default limit and perfmon is not supposed to guess how many listeners I need.

Maybe a better solution is to have perfmon count the number of perf counters it monitors and increase the limit automatically ?

Maybe a better solution is to provide an API to the developer so he can set the number of listeners himself ?

What do you think ?

Regards,
Yves