Thanks Victor. The states were idle indeed but my application was not getting the results from that connections back. I have just found that there were 2 of the threads issuing queries to the same connection in parallel.
I have some idle transactions in PostgreSQL 9.2.4 server which never end. My application was working fine on version 9.1 (BSD) but the problem appeared immediately as we ported it to 9.2.4 on Linux. The idle operations would frequently appear as COMMITs but sometimes I observed INSERTS as well.
Please note that each commit below refers to *very light* inserts of single rows which are supposed to last milliseconds. However some of the just never end even if they are not waiting on other operations. See below:
SELECT datname,usename,pid,client_addr,waiting,query_start,query FROM pg_stat_activity;
In 9.2 there's an extra column in the view that you're missing in your query: state.
If state='active', then `query` shows _currently running_ query.
Otherwise it shows _last query_ executed by the session.