As title, I have encountered a memory leak problem in loopback framework on Node js.
I can't find any problem from request API call.
So I wonder that is there any way I can dump all the objects and variables in heap memory in NodeJs when the memory usage is constantly arising, so that I can find any clue in my code.
Thanks.
Firstly, if you are running a node process in a memory restricted environment, you have to make sure that you restrict the amount of memory that is allocated to Node and to V8. What may seem like a memory leak could just be a lazy garbage collection process by the V8 engine. To supervise memory usage, I recommend the npm add-on memwatch-next.
You can force V8 to perform a garbage collection by executing your node js program with in the following manner: node --expose-gc test.js
Now, within the code, you are able to call global.gc() at set time intervals when you'd like V8 to perform an old-space cleanup.
Additional information can be found here: https://simonmcmanus.wordpress.com/2013/01/03/forcing-garbage-collection-with-node-js-and-v8/
Related
I have a nodejs application which receives and processes the REST API calls.
And I found out that its memory usage continually grow and never drop down.
Is that because my application creates obj and never recycle it in a loop?
Is there any VALGRIND equivalent tool for nodejs application?
How can I detect the memory leak on nodejs app?
One way to detect a memory leak would be to use Node's --inspect flag. You could also use memwatch and headdump modules for a more detailed analysis. This link is a great resource to start of. This one has a more in-depth explanation on what is actually happening under the hood.
I am using the node.js 6.11.3 ,cluster module, express 4.14
Seeing memory leaks slowly over a period of 1 weeks.
attached is a screenshot of the heap dumps in chrome dev tools. Cant tell the reason for the leak.click for heap dump
Unfortunately, nobody can answer where your leak comes from without accessing the entire application and environment. The real question is how do you debug a node memory leak.
First its important to try to understand how memory leaks occur in Node. How is it possible if Node has built in garbage collection? Well, variables are marked as garbage when no longer referenced. If you have code (closures etc) that still hold reference to variables, they are not collected. That is just one example. There are also dependencies that can cause memory leaks which can confuse you into thinking you have issues in your own code. And maybe you do, in the way you use the dependency.
Bottom line, its best to get familiar with this debugging process yourself so that you can understand the issues leading to the leak. Best of luck. Here is one article that is helpful.
https://www.alexkras.com/simple-guide-to-finding-a-javascript-memory-leak-in-node-js/
I have a gameserver.js file that is well over 100 KB in size. And I kept checking my task manager after each refresh on my browser and kept seeing my node.exe memory usage keep rising for every refresh. I'm using the ws module here: https://github.com/websockets/ws and figured, you know what, there is most likely some memory leak in my code somewhere...
So to double check and isolate the issue I created a test.js file and put in the default ws code block:
var WebSocketServer = require('ws').Server
, wss = new WebSocketServer({ port: 9300 });
wss.on('connection', function connection(ws) {
ws.on('message', function incoming(message) {
console.log('received: %s', message);
});
});
And started it up:
Now, I check node.exe's memory usage:
The incremental part that makes me confused is:
If I refresh my browser that makes the connection to this port 9300 websocket server and then look back at my task manager.. it shows:
Which is now at: 14,500 K.
And it keeps on rising upon each refresh, so theoretically if I keep just refreshing it will go through the roof. Is this intended? Is there a memory leak in the ws module somewhere maybe? The whole reason I ask is because I thought maybe in a few minutes or when the user closes the browser it will go back down, but it doesn't.
And the core reason why I wanted to do this test because I figured I had a memory leak issue in my personal code somewhere and just wanted to check if it wasn't me, or vice versa. Now I'm stumped.
Seeing an increased memory footprint by a Node.js application is completely normal behaviour. Node.js constantly analyses your running code, generates optimised code, reverts to unoptimised code (if needed), etc. All this requires quite a lot of memory even for the most simple of applications (Node.js itself is from a large part written in JavaScript that follows the same optimisations/deoptimisations as your own code).
Additionally, a process may be granted more memory when it needs it, but many operating systems remove that allocated memory from the process only when they decide it is needed elsewhere (i.e. by another process). So an application can, in peaks, consume 1 GB of RAM, then garbage collection kicks in, usage drops to 500 MB, but the process may still keep the 1 GB.
Detecting presence of memory leaks
To properly analyse memory usage and memory leaks, you must use Node.js's process.memoryUsage().
You should set up an interval that dumps this memory usage into a file i.e. every second, then apply some "stress" on your application over several seconds (i.e. for web servers, issue several thousand requests). Then take a look at the results and see if the memory just keeps increasing or if it follows a steady pattern of increasing/decreasing.
Detecting source of memory leaks
The best tool for this is likely node-heapdump. You use it with the Chrome debugger.
Start your application and apply initial stress (this is to generate optimised code and "warm-up" your application)
While the app is idle, generate a heapdump
Perform a single, additional operation (i.e. one more request) that you suspect will likely cause a memory leak - this is probably the trickiest part especially for large apps
Generate another heapdump
Load both heapdumps into Chrome debugger and compare them - if there is a memory leak, you will see that there are some objects that were allocated during that single request but were not released afterwards
Inspect the object to determine where the leak occurs
I had the opportunity to investigate a reported memory leak in the Sails.js framework - you can see detailed description of the analysis (including pretty graphs, etc.) on this issue.
There is also a detailed article about working with heapdumps by StrongLoop - I suggest to have a look at it.
The garbage collector is not called all the time because it blocks your process. So V8 launches GC when it thinks it's necessary.
To find if you have a memory leak I propose to fire up the GC manually after every request just to see if your memory is still going up. Normally if you don't have a memory leak your memory should not increase. Because the GC will clean all non-used objects. If your memory is still going up after a GC call you have a memory leak.
To launch GC manually you can do that, but attention! Don't use this in production; this is just a way to cleanup your memory and see if you have a memory leak.
Launch Node.js like this:
node --expose-gc --always-compact test.js
It will expose the garbage collector and force it to be aggressive. Call this method to run the GC:
global.gc();
Call this method after each hit on your server and see if the GC clean the memory or not.
You can also do two heapdumps of your process before and after request to see the difference.
Don't use this in production or in your project. It is just a way to see if you have a memory leak or not.
I'm writing a simple cms in Node.js, Express and MongoDB. I'm planning to run a different Node.js process for every site. The problem is that after startup the process takes about 90m of RAM and for me it's too big (eight site take all server RAM). This memory is taken after the first connection to the site and other connections don't affect the memory.
Is there a guideline or a list of "best practices" to optimize this memory usage? I'm trying to track where the memory is allocated with process.memoryUsage() or a similar function but it's not simple to do this.
Is not a problem of memory leaks or something similar because the memory usage doesn't grow up after the first connection, so probably the optimization could be in loading less modules or do something differently...
The links below may help you to understand and detect memory leaks (if they do exist):
Debugging memory leaks in node.js
Detecting Memory Leaks in Node.js Applications
Tracking Down Memory Leaks in Node.js
These SO questions may also be useful:
How to monitor the memory usage of Node.js?
Node.js Memory Leak Hunting
Here is a quick fix, a node.js lib that will restart the any node process once it reaches a certain size.
https://github.com/DoryZi/memory_limiter
Set the --max_old_space_size CLI flag to control the maximum heap size. There's a post that describes Running a node.js app in a low-memory environment
tl;dr; Try setting this value, in megabytes, to about 80% of the maximum memory footprint you want node to try to remain under. e.g. to run app.js and keep it under 500MB RAM used
node --max_old_space_size=400 app.js
This setting is also described in the Node JS CLI documentation
I've just fixed a memory leak in my node application which was in the heap of node.
I've profiled that with Google's Profiler and managed to fix the memory leak.
Now my app is running again for some time, and I've seen that the heap size is pretty constant. No memory leak anymore. But when I check my server's free RAM, I see a decrease...
When I restart my node server the RAM is up to it's normal free RAM.
Now I've heard about that Node.js can save objects and stuff outside of the heap. I think that is what's causing the memory leak here.
How can I see what's taking up the memory? Can't really profile anything, or can I?
I'm using:
node.js: v0.8.18 and
socket.io: v0.9.13
Some other node modules that I'm using are: nodetime, heapdump (will delete this, though), jquery, crypto, request and querystring.
Some graphs:
Free OS memory and
Node RSS and Heap used