out of memory on idle machine

[Olly Betts]

On Wed, Feb 03, 2021 at 07:59:43AM -0400, David Bremner wrote:
> Gregor Zattler <telegraph at gmx.net> writes:
> > A Xapian exception occurred finding message: Db block overwritten - are there multiple writers?.
> 
> I have included the Xapian list in copy in case that message rings a
> bell.

There was a bug fixed in 1.4.7 which incorrectly resulted in this error
message, but it seems from the quoted text you're using 1.4.11.

> I guess you know there are not multiple writers in your setup.

There's a lock file locked by fcntl() which protects against multiple
writers, so someone/something would have need to have deleted that
behind Xapian's back, or else a bug somewhere in the locking code stack.

(Aside from that bug, probably the most common case here over time has
been that someone deleted the lock file thinking it's "stale", but it's
not the mere presence of the file that means the lock is held.  It's
not at all frequent, but perhaps we should adjust this message to better
reflect that.)

Have you tried xapian-check on this database?

> Olly Betts mentioned in a different thread that he will build a version
> of xapian 1.4.18 for buster backports, so trying with that is probably a
> good step when it is available.

Yes - 1.4.18 packages are now in Debian testing, so hopefully I can get
this done soon.

> % xapian-delve -1 -A XDIRECTORY ~/Mail/.notmuch/xapian | sort -u > delve.txt

FWIW, the output should be sorted and unique already (sorted by byte
order, so equivalent to `LC_ALL=C sort`).

Cheers,
    Olly