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Alex Tondello
Alex Tondello

Reputation: 141

Meteor.setTimeout() memory leak?

I've created a new project with just one file (server.js) on the server with this tiny piece of code that does nothing. But, after running it, my node process is using about 1Gb of memory. Does anyone know why?

for (var i = 1000000; i >= 0; i--) {
    Meteor.setTimeout(function(){},1000);
};

Apparently Meteor.setTimeout() function does or uses something (closure?) that prevents GC from clearing memory after it has been executed. Any ideas?

Upvotes: 2

Views: 162

Answers (1)

Brett McLain
Brett McLain

Reputation: 2010

Since you are calling this on the server side, Meteor.setTimeout is a lot more complex than it appears on the surface. Meteor.setTimeout wraps setTimeout with Meteor.bindEnvironment(), which is essentially binding the context of the current environment to the timeout callback. When that timeout triggers, it will pull in the context of when it was originally called.

A good example would be if you called a Meteor.method() on the server and used a Meteor.setTimeout() within it. Meteor.method() will keep track of the user who called the method. If you use Meteor.setTimeout() it will bind that environment to the callback for the timeout, increasing the amount of memory needed for an empty function().

As to why there isn't any garbage collection occurring on your server, it may not have hit it's buffer. I tried running your test and my virtual memory hit around 1.2gb, but it never went any higher, even after subsequent tests. Try running that code multiple times to see if memory consumption continues to increase linearly, or if it hits a ceiling and stops growing.

Upvotes: 1

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