Unicorn Eating Memory

Question

I have a m1.small instance in amazon with 8GB hard disk space on which my rails application runs. It runs smoothly for 2 weeks and after that it crashes saying the memory is ful

Answer 1

I think you are conflating memory usage and disk space usage. It looks like Unicorn and its children were using around 500 MB of memory, you look at the second "-/+ buffers/cache:" number to see the real free memory. As far as the disk space goes, my bet goes on some sort of log file or something like that going nuts. You should do a du -h in the data directory to find out what exactly is using so much storage. As a final suggestion, it's a little known fact that Ruby never returns memory back to the OS if it allocates it. It DOES still use it internally, but once Ruby grabs some memory the only way to get it to yield the unused memory back to the OS is to quit the process. For example, if you happen to have a process that spikes your memory usage to 500 MB, you won't be able to use that 500 MB again, even after the request has completed and the GC cycle has run. However, Ruby will reuse that allocated memory for future requests, so it is unlikely to grow further.

Finally, Sergei mentions God to monitor the process memory. If you are interested in using this, there is already a good config file here. Be sure to read the associated article as there are key things in the unicorn config file that this god config assumes you have.