[Xapian-discuss] Threaded test (in C++) to reproduce our database problems

[Eric B. Ridge]

On 6/16/04 9:43 PM, "Olly Betts" <olly@survex.com> wrote:

> Great - this should be very helpful.

I hope so.  This has been driving us nuts.  We've got this problem on our
production systems and it's killin' us.
 
> That's less odd.  After the writer has flushed twice, readers will get
> this exception - they need to call reopen() and restart the operation.

Woah, can you elaborate here?  We're not calling reopen() anywhere.  Not in
this little test, and not in our production code.

<short pause to RTFM>

Hmm.  Sounds like we should just catch the DatabaseModifiedError, do the
reopen() and just try again, eh?

Our production code (like this test) does call flush() every-so-often, and
it's less than every 1000 add_document() calls, so we can probably track
when we do a flush() and do the re-open ourselves.

However, what if a reader thread is in the middle of reading back documents
while we do the flush() in the writer thread?  Sounds like these need to be
synchronized in some way.

> 
>> Writer:  ERROR=Db block overwritten
> 
> But the writer thread shouldn't get this unless there's another writer.

I thought this one was strange too.  But you can see from the attached
example, just one writer.

> I can't see anything wrong from a quick read through.  I'm right in the
> middle of something right now, but I'll give this a whirl in the next
> day or so.

If you happen to get to this sooner, send me your mailing address offline...
free pizza and beer.  ;)

eric