Re: Postmaster hangs

Karen Pease <meme@daughtersoftiresias.org> writes:
> It'll get through about three or four of them (out of hundreds) before
> it locks up.  Now, before lockup, postmaster is very active.  It shows
> up on top.  The computer's hard drives clack nonstop.  Etc.  But once it
> locks up (without warning), all of that stop.  Postmaster does nothing.
> The computer goes silent.  I can't ctrl-break the psql process.  If I
> try to start a new psql process, it won't get past the password prompt
> -- psql will hang.  All Apache processes involving postgres queries
> hang.  The postgres server cannot be restarted by any normal means (the
> only solution I've found that works is a reboot).  And so forth.

This sounds to me like it's a kernel problem, possibly triggered by
misbehaving disk hardware.  What you might try to confirm is a kill -9
on whichever postgres backend seems to be stuck.  If that fails to
remove the process, then it's definitely a kernel issue --- try googling
"uninterruptible disk wait" and similar phrases.

The cases that I've run into personally have been due to poor error
handling for a disk failure condition in a kernel-level disk driver.
If that's what it is for you, the bottom-level problem might be an
unreadable disk block somewhere.  Or it might just be a garden variety
kernel bug.  What's the platform?

            regards, tom lane