Recently I had do integrate java and php application where PHP is runned from within web app. I have used servlet filter to do authentication (via spring security) with rest of applications. Problem arised when I needed to read in this filter some request parameters because then PHP backend hanged during every POST request.
Thread stopped waiting at RandomAccessFile (named pipe).
I suppose that accessing request parameters in POST caused reading request body which causes depletion of input stream. Then, PHP cgi app tries to read it again but hangs.