rbheap

README

rbheap

A tool for working with and analyzing Ruby processes' heap dumps created via ObjectSpace.dump_all.

How to dump the heap

Dumping the heap from a running Ruby process is not very difficult as long as your app has required the rbtrace gem.

1. Add the rbtrace gem to your application, and require it in your code when the application boots.
2. Find the PID of your running Ruby process.
3. Run the following to dump your process' heap to a file called heap.jsonl:

   rbtrace -p $PID -e 'Thread.new{GC.start;require "objspace";File.open("heap.jsonl","w"){|f|ObjectSpace.dump_all(output: f)}}'
   

Commands

leak

The leak command is intended to help track down memory leaks. By requiring three heap dumps as input, it attempts to find memory that showed up in dump #2, and is still there in #3.

The idea is to take a heap dump shortly after the application starts and before it's had much of a chance to leak memory. Then take another heap dump after it's been running for a while and leaked memory. And finally take a third heap dump after it's been running for a while longer and leaked even more.

But comparing these three dumps and extracting only the objects which are held in memory during heap dumps #2 and #3, we should mostly be left with objects which are leaked memory.

Usage:
  rbheap leak [flags] <dump-A> <dump-B> <dump-C>

Flags:
  -f, --format string   output format: "hex" / "json" (default "hex")
  -h, --help            help for leak
  -v, --verbose         print verbose information

Credits

This project is mostly based on the ideas and concepts from the following articles:

• What I Learned About Hunting Memory Leaks in Ruby 2.1 by Peter Wagenet
• How I spent two weeks hunting a memory leak in Ruby by Oleg Dashevskii
• Debugging memory leaks in Ruby by Sam Saffron