[ruby-core:105081] [Ruby master Bug#18134] Memory leak with master

Issue #18134 has been updated by MSP-Greg (Greg L).


I'm not that familiar with the best way to measure Ruby memory use.

The following code:
```ruby
loops = ARGV[0] || 500_000

smem = "smem -c 'pid pss rss uss command'"

env = ENV.to_h
env_c = nil

GC.start; GC.compact
system smem

100_000.times { env_c = env.dup }

puts '', "Duped hash #{loops} times", ''

GC.start; GC.compact
system smem
```

Yielded the following.  Both Ruby 3.0.2 and master show an increase in memory, but master uses 10 times as much...
```
  PID      PSS      RSS      USS
  865    20609    22484    20072  Ruby master start
  865   120927   122808   120680   "     "    end
                          100608              increase

  870    20468    22216    19872  Ruby 3.0.2 start
  870    30492    32268    29912   "     "   end
                           10040   "     "   increase
```

----------------------------------------
Bug #18134: Memory leak with master
https://bugs.ruby-lang.org/issues/18134#change-93485

* Author: MSP-Greg (Greg L)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.1.0dev (2021-08-26T10:47:48Z master ef10e8a1eb) [x64-mingw32]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
While working on code to test Puma’s performance, I noticed a memory leak using WSL2 Ubuntu 20.04 and Ruby master.  The leak seemed proportional to the number of requests made, and independent of the response size, either headers or body.  Locally, I was running up to 2 million requests.  The code used @ioquatix’s version of wrk and smem for measuring memory use.  I ran GC.start and GC.compact before checking memory.  The Puma configuration was using `fork`.

I’ve got a lot of Ruby versions on Windows, but haven’t created the same setup for Ubuntu.  So, I took the above code and ran it on GitHub Actions Ubuntu 20.04.  Ruby 2.5.9, 2.7.4, and 3.0.2 did not have the memory leak, but master had the same leak I saw locally.

Puma and one of its dependencies (nio4r) are both extension gems.  Has there been an ABI change that might affect the code?

I can try to bisect it if that would be helpful.

Thanks, Greg



-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:[e-mail]?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>