I have a staging application (thank goodness its not in production yet), and it started crashing my server because it was using too much memory. However, I’m not really sure why since I haven’t made changes for over a long time. In my logs it says: Aug 15 06:58:17 PM [os_mon] cpu supervisor port …

Do :observer.start() in iex (on the server) and go to the memory tab. Do stuff with the app and check for increased memory usage.

Erlang/OTP 24 [erts-12.3.2.2] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit] Interactive Elixir (1.12.3) - press Ctrl+C to exit (type h() ENTER for help) iex(name@server)1> :observer.start() ** (UndefinedFunctionError) function :observer.start/0 is undefined (module :observer …

To be clear, the above does not mean your server is running out of memory. It just means Erlang tooling for measuring memory/cpu usage has terminated, which will always be logged when Erlang shuts down. So, without further evidence, all we know is that Erlang is shutting down. Do your logs say some…

OOM errors are hard to debug. :observer and LiveDashboard may help, However, when **** happens, it usually happen quick enough that you don’t get the chance to observe clearly. I can only offer a few high memory pitfalls that I have seen: Do you have process that do lot of work then idle for a lo…

So, without further evidence, all we know is that Erlang is shutting down. Do your logs say something else? Do you have metrics that say something else? I am using render, and I noticed the server going unhealthy and then dies then restarts. When I looked at the logs, those are the error messages…

Yeah, it’s a bit tough. In my case, it happens when I hit an API endpoint and I haven’t been able to find a culprit. It could be a long idle process, but if my server is restarting then that idle process would have died. Thanks for the helpful hints. I’ll try to look more closely.

Optimizing ram usage is usually not worth the effort, this is a compromise GC languages have. There is one thing when ram usage spikes happen and another when there is memory leaking, and judging by your description, you most probably have a spike. For the record, what are the specs of your machin…

Not for nothing, but this is what I find APMs (like AppSignal, Scout, DataDog, NewRelic, etc) great for. Doesn’t always give you what you need, but more often than not you can see what was happening when things went off the rails.

For the record, what are the specs of your machine? 512mb then I upgraded to 2gb. There is one thing when ram usage spikes happen and another when there is memory leaking, and judging by your description, you most probably have a spike. I just can’t imagine my small application spiking up to …

It depends how much of that space is left for the application, since the OS and other applications might use a part too. Since the application runs after increasing ram, just look at the profiler and check what is happening with the ram.

How do I debug this?

Questions & Help Questions

derek-zhou August 15, 2023, 2:14pm 14

For low RAM VMs, you may want to try to run in 32 bit to conserve memory. I have a blog post on this, albeit with fly.io: