Re: hung postmaster when client machine dies?

On Thu, 29 Jan 2004 17:00:27 -0800
Mark Harrison <mh@pixar.com> wrote:

> 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?
>

When a machine simply "goes away" (crashed, unplugged) no packets are
sent indicating the socket has closed so PG doesn't know the socket is
closed and cannot rollback the transaction. (This is true of any
tcp-based protocol).

If that connection had a transaction open it'll likely have rows locked.
Killing PG caused it to rollback that transaction freeing those locks.
Eventually PG would have found out the socket was dead.  Most likely if
it tried to write to it.

--
Jeff Trout <jeff@jefftrout.com>
http://www.jefftrout.com/
http://www.stuarthamm.net/