Enabling/disabling GC manually causes rack-perftools_profiler to hang

[fimmtiu]

So I'm profiling a Rails 3.2 app on Ruby 1.9.3 which has the following filter in ApplicationController to reduce the frequency of GC runs:

@@last_gc_run = Time.now
around_filter do |c, &action|
  GC.disable
  rv = action.call()
  if Time.now - @@last_gc_run > 1.0
    GC.enable
    GC.start
    @@last_gc_run = Time.now
  end
  rv
end

Ordinarily, this makes things about 30% faster. If I hit http://mysite/controller/action, it runs as expected, only taking a few seconds... but if I hit http://mysite/controller/action?profile=1, it causes the Ruby process to spin up to 100% CPU usage and run forever. Doesn't respond to signals, needs to be SIGKILLed. Removing this around_filter makes ?profile=1 requests work normally again.

My configuration is { :default_printer => :text, :mode => :walltime }, although the bug seems to occur no matter which printer I use.

[fimmtiu]

Sorry, forgot to mention: this is all running on Apache 2.2 with Passenger 3.0.11.