Question

It seems like I always get this error on one of my scripts:

/Users/amosng/.rvm/gems/ruby-1.9.3-p194/gems/ruby-prof-0.11.2/lib/ruby-prof/profile.rb:25: stack level too deep (SystemStackError)

Has anyone encountered this error before? What could be causing it, and what can I be doing to prevent it from happening?

I run my ruby-prof scripts using the command

ruby-prof --printer=graph --file=profile.txt scraper.rb -- "fall 2012"

Edit I’m on Mac OS X, if that matters. Doing ulimit -s 64000 doesn’t seem to help much, unfortunately. Here is what ulimit -a gives:

$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
file size               (blocks, -f) unlimited
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) unlimited
open files                      (-n) 256
pipe size            (512 bytes, -p) 1
stack size              (kbytes, -s) 64000
cpu time               (seconds, -t) unlimited
max user processes              (-u) 709
virtual memory          (kbytes, -v) unlimited

Edit 2

Andrew Grimm’s solution worked just fine to prevent ruby-prof from crashing, but the profiler seems to have problems of its own, because I see percentages like 679.50% of total time taken for a process…

Answer 1

One workaround would be to turn tail call optimization on.

The following is an example of something that works with TCO on, but doesn’t work when TCO is off.

RubyVM::InstructionSequence.compile_option = {
  :tailcall_optimization => true,
  :trace_instruction => false
}

def countUpTo(current, final)
  puts current
  return nil if current == final
  countUpTo(current+1, final)
end

countUpTo(1, 10_000)