The original km Ruby gem is not thread safe. We have released a new gem, kmts, that is threadsafe.
We are hosting our documentation for our Ruby API here: support.kissmetrics.com/apis/ruby
Version 1.0.2 of the kmts gem had an issue where it was found to not actually be thread safe. If you were using version 1.0.2 of the kmts gem, you were likely using non thread-safe code. In this case, you will want to either switch to using the non thread-safe km gem, or update your code to use the thread-safe kmts gem version >= 2.0.0.
gem install km
This gem includes SaaS calls. For more information please refer to: support.kissmetrics.com/getting-started/saas_basics
For the methods used, see the rdoc for SaaS