A case of "Broken Pipe" error in Rails

Have you ever seen "Broken PIPE" error in Rails?

It somehow like this:

*** Exception Errno::EPIPE in Passenger RequestHandler (Broken pipe) (process 22235):
    from /usr/lib/ruby/gems/1.8/gems/passenger-2.1.2/lib/phusion_passenger/rack/request_handler.rb:67:in `write'

This error seems appear when your program interacts improperly with external programs. In my case, it happened to me in a project that I used XMLRPC library to remotely communicate with some web services.

My implementation for that feature is as following:
- create a XMLRPC connection object
- use that XMLRPC object every time calling a webservice API

There some other guys had been headache with that error also:
http://gaveen.owain.org/2008/04/errnoepipe-broken-pipe-mysql-error-in.html
http://stackoverflow.com/questions/1082166/exception-errnoepipe-in-passenger-requesthandler-broken-pipe
http://stackoverflow.com/questions/4351624/ruby-on-rails-errnoepipe-broken-pipe

and the reasons they found come around Passenger or Mysql.

In my case, I've got the same thing even with upgrading Passenger or migrating to another web server.
After a lot of retries, I've found that if I call the API very often, "Broken pipe" doesn't appear, but if I stop doing anything for a while and then call the API, it does happen. That observation led me to a guess: XMLRPC connection object may be broken after a certain amount of time (timeout). Excellently, that's exactly right! I then changed my implementation so that every time calling a webservice API, I use a newly created XMLRPC connection object instead of using the same XMLRPC connection object for every API calls.

That solved my problem!