Nick Wellnhofer wrote on 2/14/17 9:03 AM:
On 13/02/2017 20:44, Serkan Mulayim wrote:
1- How do we check that the index is healthy for SEARCHING (e.g. creating a
searcher) without a crash? As I see there is no problem in creating a Searcher
even if there is a lock (write.lock or merge.lock)
First of all, Lucy should never "crash" in the sense of a segfault. If it does,
this is a bug that should be reported.
Unless your index is on a shared volume like NFS, it can always be searched.
One trick to keep in mind is that if the index underlying a Searcher changes (as
through indexing or document deletion), you must detect that change and open a
new Searcher. Because of mmap it's very fast to spawn a new Searcher, but
sometimes you'll see stale results if you persist one too long.
An example of how Dezi does that here:
https://metacpan.org/source/KARMAN/Dezi-App-0.014/lib/Dezi/Lucy/Searcher.pm#L406
tl;dr is that Dezi writes its own index metadata header that includes a UUID and
timestamp for the last time the index was updated, and checks that UUID against
the current Searcher to know if it is stale and needs to be re-created.
--
Peter Karman . https://peknet.com/ . https://keybase.io/peterkarman
