hung postmaster when client machine dies?

We recently had an incident where a linux box went down with
a kernel error.  A process on the box had an open connection
to a postgres session, and was in a transaction.

This situation was noticed when other processes connected to
postgres would not respond.

We observed that there was postmaster connected to the ip address
of the downed machine with an "in transaction" status.  Killing
that processes unblocked the other processes.

Is this expected behavior?  Was postgres simply waiting for
a failure from the TCP/IP layer?

We're now running a watchdog process that pings machines for
which a postmaster is running and killing that process if
the machine is not contactable for a certain period of time.
Thanks to whoever made the status information show up in ps
output!

Unfortunately, we didn't capture the process data... if this
would help we can attempt to reproduce the situation.

Many TIA,
Mark

--
Mark Harrison
Pixar Animation Studios
Emeryville, CA