Re: "recovery mode"

"Steve Wolfe" <steve@iboats.com> writes:
>    What exactly is "recovery mode"?  Today, the backend went into recovery
> mode, and simply wouldn't do anything.  Not using any CPU, and would not go
> away even with a kill -9.  I ended up having to reboot the machine to get
> the database working again....

I don't think recovery mode actually does much in 7.0.* --- I think it's
just a stub (Vadim might know better though).  In 7.1 it means the thing
is replaying the WAL log after a crash.  In any case it shouldn't
create a lockup condition like that.

The only cases I've ever heard of where a user process couldn't be
killed with kill -9 are where it's stuck in a kernel call (and the
kill response is being held off till the end of the kernel call).
Any such situation is arguably a kernel bug, of course, but that's
not a lot of comfort.

Exactly which process were you sending kill -9 to, anyway?  There should
have been a postmaster and one backend running the recovery-mode code.
If the postmaster was responding to connection requests with an error
message, then I would not say that it was locked up.

            regards, tom lane