notmuch new crashing due to out of memory - how to deal with it

[Hamish D]

Hello

I recently deleted almost 30000 old messages from my maildirs, and
since I did that, notmuch new has not managed to complete.  I have it
running on a server with 1 GB of RAM, and the output is telling me

    Cleaned up 25515 of 29803 messages (1m 10s remaining).

at the point it is killed.  I have followed it up to this point with
top and free and I can see memory usage growing to something like
700MB (RES) at which point the process is killed.

I am using notmuch 0.17 (from the debian jessie package) on debian
wheezy 64 bit.

Any pointers as to what to do to get past this point would be greatly
appreciated.  If I have just deleted that many messages should I just
expect notmuch to use that much memory?  I guess I could enable swap
and hope that allows enough memory to get past this operation.

I did also try running it with NOTMUCH_TALLOC_REPORT, but that didn't
produce a report (though I was unsure if I needed to rebuild notmuch
before that would work).

Happy to build notmuch from source if this might be an interesting bug
worth tracking down.

Hamish