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Forgot to add a link to the repo on github: https://github.com/zzak/segfault_spec.rb

I'm also getting segfaults on Ruby 2.0.0. It seems to be related to threading or forking. Can't quite put my figure on it. All I can say is that I don't get in when running my web app in WEBrick on my Mac, but if running it on my CentOS server with Phusion Passenger using the smart spawn method, I get it all the time, about every 10th request it segfaults. Setting passenger to a conservative spawn method (one request per process) reduces the segfault rate considerably, but they still occur.

Here's a stack overflow thread about it, with a response I left on there with a bit more information about my experiences: http://stackoverflow.com/questions/15315809/segfault-error-in-sinatra-after-upgrading-to-ruby-2-0-beta/15492401#15492401

I also reported this to the Phusion Passenger Google Group before realising it's a problem with ruby 2.0.0: https://groups.google.com/forum/?fromgroups=#!topic/phusion-passenger/iEOE4shl_jE

Here's a log including numerous segfaults from my CentOS server running Phusion Passenger: https://gist.github.com/Wardrop/5179380

Either way, it looks like something common to web applications is causing this, or perhaps web application frameworks are so far the most common cases in which Ruby 2.0.0 is being used.

Here's a backtrace I got in gdb: http://pastie.org/7064676. rb_gc_mark_unlinked_live_method_entries seems suspicious and related to what the script does.

They've obviously done work on the garbage collector for Ruby 2.0. This is likely a bug introduced as result of that. Good work tracking it down judofyr.

After working with charliesome we've now found an even simpler test case:

http://eval.in/13339

This always segfaults for me on trunk.

=begin
Magnus and I reduced this down to an even simpler^2 test case:

loop do
def x
"hello" * 1000
end

method(:x).call

end

http://eval.in/13344
=end

nobu-san, this will loop forever when the bug is fixed. Perhaps change it to 100_000.times?

I'd set it to a duration rather than a set number of iterations. I've see it go for 2 seconds on my machine before segfault'ing. 3 seconds should fail almost every time.

start_time = Time.now
while (Time.now - start_time) < 3
  def x
    "hello" * 1000
  end
  method(:x).call
end

charliesome (Charlie Somerville) wrote:

nobu-san, this will loop forever when the bug is fixed. Perhaps change it to 100_000.times?

Sure, I've forgot it before the commit.

Thank you nari-san and everyone who helped with this.

Should this be backported as well?

zzak (Zachary Scott) wrote:

Thank you nari-san and everyone who helped with this.

Should this be backported as well?

Yeah, this fix should be backport to 1.9.3 and 2.0.0.

Eagerly awaiting the backport. Can someone please leave a comment when it's back-ported to ruby-2.0.0 head?

wardrop (Tom Wardrop) wrote:

Eagerly awaiting the backport. Can someone please leave a comment when it's back-ported to ruby-2.0.0 head?

The backport request ticket is here.
https://bugs.ruby-lang.org/issues/8163
You might want to watch this ticket for your purpose.

Thanks for that. By the way, I've applied the patch to my production server. Write me down as another happy customer :-)

Might be related to https://bugs.ruby-lang.org/issues/8056