Cucumber Performance 1

Posted by jcnnghm Wed, 23 Feb 2011 22:05:00 GMT

Cucumber with celerity running under capybara and celerity was erroring out with Java OutOfMemory exceptions. In looking to fix the problem, I also decided to look at how various jruby invocation switches would alter the performance.

First, to set your jruby invocation options, in your cucumber environment file, add the following:

require 'culerity'
Culerity.jruby_invocation = 'jruby -J-Xmx2500m -J-Xms2500m -J-Xmn512m'

I recommend setting the Xmx and Xms options, the maximum and minimum Java heap sizes, to the same value, tailored to your environment. Xmn controls the generation size for the garbage collector. 20% or so of the total heap size seems to be the sweet spot, and allows the garbage collector to run effectively over this memory.

While increasing the java heap size temporarily alleviated the issue, it didn’t address it entirely, there seemed to be a memory leak. I started poking around, and found this commit,, in the culerity repository. After some experimentation, I settled on adding the following to my environment file:

After do
  if page.driver.is_a?(Capybara::Driver::Culerity)

clearproxies can be replaced without closebrowsers, but it impacts performance more than clear proxies and increases memory usage. The clear_proxies method frees the rjuby remote object proxies, which in turn allows the garbage collector to reclaim the memory that they occupy. This reduced my overall memory usage for the testing suite by over a gigabyte, and had a very minor runtime improvement. At the same time, I also tried both the –fast and the –server options on the rjuby invocation, and found that they didn’t seem to have any significant positive impact on either memory usage or runtime.

jruby -J-Xmx2500m -J-Xms2500m -J-Xmn512m
Mem 1,066,412MB
with page.driver.class.server.clear_proxies

Mem 2,111,728MB
without page.driver.class.server.clear_proxies

Mem 1,549,804MB
with page.driver.class.server.close_browsers

jruby -J-Xmx2500m -J-Xms2500m -J-Xmn512m --fast --server
Mem 1,068,840MB
with page.driver.class.server.clear_proxies

Mem 2,945,160MB
without page.driver.class.server.clear_proxies

jruby -J-Xmx2500m -J-Xms2500m -J-Xmn512m --fast
Mem 1,081,064MB
with page.driver.class.server.clear_proxies

jruby -J-Xmx2500m -J-Xms2500m -J-Xmn512m --server
Mem 1,089,388MB
with page.driver.class.server.clear_proxies

This wasn’t scientific, but it did stop cucumber from leaking so much memory.


Use the following link to trackback from your own site:

  1. uplibenoupe Fri, 04 Mar 2011 18:59:04 GMT

    I will say again that I have never, and would never, harm a child. It sickens me that people have written untrue things about me.