ruby debugging: print line number when taking too long

benchmarking, profiling, ruby

Solution

require 'timeout'

def do_something
  Timeout::timeout(9) do
    sleep 10
  end
rescue Timeout::Error => e
  puts "Something near line #{__LINE__} is taking too long!"
  # or, count backwards in method
  puts "Line #{__LINE__ - 5} is taking too long!"
end

do_something

This will stop execution if the timeout block runs out of time and raise a Timeout error. If you want to continue execution, you might do better with benchmark:

require 'benchmark'

time = Benchmark.realtime do
  sleep 10
end
puts "Line #{__LINE__ - 2} is slow" if time > 9

One benchmark block can have multiple timers:

Benchmark.bm do |b|
  b.report('sleeping:') { sleep 3 }
  b.report('chomping:') { " I eat whitespace ".chomp }
end

See more about benchmark here: http://ruby-doc.org/stdlib-1.9.3/libdoc/benchmark/rdoc/Benchmark.html

If you want to keep track of the line number being executed, why don't you try passing it in to a custom method like so:

def timethis(line, &block)
  if Benchmark.realtime(&block) > 2
    puts "Line #{line} is slow"
  end
end

timethis(__LINE__) { sleep 1 }

Problem

Is there a way in Ruby to have it print the `__LINE__` number of code (at my script level, not required gems) it's working on if taking longer than 9 seconds (adjustable)? For debugging I am getting it to print verbose output of what it's trying to do, where it is in the code etc., rather than silently sitting for long periods of time. A flaky situation makes it unpredicable how far it gets before something times out, so successive advancing doesn't apply here. EDIT Something like a trap would work, such that: - The original line number and hopefully code get remembered (both benchmark and timeout gems lose track of `__LINE__` for instance.... Maybe there is a way to push it off to another .rb file to manipulate the stack to include my file & line of interest?) - When the overtime warning prints, execution still continues as if nothing had changed.

Original source