Develop Reference

Fail to load heapsnapshot

I am trying to to analyze my node.js memory leak using V8 heapsnapshot and Chrome Developer Tool.
Unfortunately, dev tool always crash at "Building postorder index...".
The heapsnapshot files are between 70mb and 620mb.
Any other way to analyze the memory heap file?
What can I do to find out the cause of the crash?

gc-expose effect in Node.js for long run application

I have an issue with memory limit in my machine. So I have to push my memory usage in Node.js below 150MB. Therefore I run my application with --gc-expose parameter and called global.gc() in application each cycle.
So my question, is there any bad effect or deficiency if my app will run for long time ? FYI, I started this app with PM2.
Thanks

Getting Javascript Memory Profiling During Test Suite

We inherited a fairly large Javascript application and test suite and have recently started to have issues with memory usage during testing.
Whilst we attempt to fix the issues our test suite has, we'd like to stem the flow of new leaks into the application. Are there any tools that we can integrate with our CI build to get memory profiling? Even some basic memory allocation statistics would help us see whether a suite is eating through memory.
We're running Jasmine with PhantomJS. The closest I've been able to find is Chrome's window.performance.memory, but it's only for the whole of Chrome and seems like it might be quite volatile.

I am not aware of any automated memory statistics 3rd party applications for javascript that would work in CI. Take a look at Google's memory profiling post: https://developer.chrome.com/devtools/docs/javascript-memory-profiling

High CPU Utilization for Meteor.js

A meteor.js 0.82 app is running on an Ubuntu 14.04 server with 2GB memory and 2 cpu cores. It was deployed using mup. However the CPU utilization is very high, htop reports 2.72 load average.
Question: How do I find out which part of the app is causing such a high CPU utilization? I used Kadira but it does not reveal anything taking up alot of CPU load afaik.
Does Meteor only use a single core?

I had a similar problem before with Meteor 0.8.2-0.8.3. Here are what I have done to reduce the CPU usage, hope you may find it useful.
double check your functions, ensure all function has proper return, and does properly catch errors
try to use a replicaSet and oplog mongo convert standalone to replica set
write scripts to auto kill and resprawn a node process if it exceeds 100% cpu usage
utilize multi-core capability by starting 2 processes (edit you have done already) and configure and setup load-balance and reverse proxy
make sure to review your publish and subscription and limit what data to be sent to client (simply avoid something like Collection.find();)
Personally I recommend Phusion Passenger, it makes deploying Meteor applications an ease, and I have used it for several projects without any major problems.
One more thing, avoid running the processes in root (or privilege user), you should be running your apps in another user like www-data. This is for obvious security reason.
P.S. and multiple mongo processes showing in htop are threads under a master process, you can view it in tree mode by pressing F5.

Phantomjs dies by high memory consumption

We are using phantomjs to run our qunit tests page on our TFS build server. Our version of test runner is built from below example
https://github.com/ariya/phantomjs/blob/master/examples/run-qunit.js
Over a period of time number of tests increased from hundreds to couple of thousands and on a fine day phantomjs started crashing. It literally dies saying upload the dump and when you see the dump it 0kb !!
When we took a closer look at it on process explorer we found that memory consumption by phantomjs keeps going up as phantomjs is running tests and eventually crashes somewhere 833MB.
Yes the same amount of memory was being utilized by chrome and IE ! And Yes-Yes our tests were leaking memory :(. We did fixed it, memory utilization is lowered by 50% on chrome and IE and we expected phantomjs will handle it now. But no, phantomjs still kept crashing, process explorer shows same memory consumption.
http://phantomjs.org/api/webpage/method/close.html
According to above documentation phantomjs releases heap allocation just on close ? Could that be the reason why our fixed test consumed less memory on chrome but not phantomjs ? And last how to fix this ? How to make phantomjs keep garbage collecting javascript objects to reduce heap allocation ?
Update 1 - 07/28
We took a work around. I did modified my script to execute my tests module by module. In loop after executing all tests for a module I call page.close so it releases the memory for each module and never keeps building the dead heap of objects. Not closing this question since since its a workaround and not a solution. Hope creators will fix this sometime.

There is a static method, QWebPageSettings::clearMemoryCache, that invokes WebKit's garbage collection. However, it clears all QWebPage memory cache for every instantiated QWebPage object and is therefore, currently, unsuitable for including as an option in PhantomJS.
The Github pull request is available here:
https://github.com/ariya/phantomjs/pull/11511
Here's the Google Groups discussion:
https://groups.google.com/forum/#!msg/phantomjs/wIDp9J7B-bE/v5U31_mTbswJ
Until a workaround is available, you might break up your unit tests into blocks on separate pages. It will take a change to QtWebkit's implementation and how memory/cache is handled across QWebPage objects.
Update September 2014:
https://github.com/ariya/phantomjs/commit/5768b705a0
It looks like support for clearing memory cache was added, but there is a note about my original comment in the commit.

I managed to work around it by setting the /LARGEADDRESSAWARE flag
If you have visual studio installed, run from a visual studio command prompt
editbin /LARGEADDRESSAWARE <pathto>/PhantomJS.exe