PG::Error: Wait on socket error (WaitForMultipleObjects)

I am using Rails 3 app on windows with ruby 1.9.3p551 and postgres(9.1.3) database. While running load test for the app, we're observing few request failure with error PG::Error: Wait on socket error (WaitForMultipleObjects) originating from activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:1153:in 'async_exec'.

Tried increasing connection pool of Postgres and checkout_timeout but same error keeps on coming during load test. Any idea/help on what could cause this issue will be very helpful. also, What could be the solution for this as at this time, we cant migrate to different version of ruby.

Thanks