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

[Olly Betts]

On Wed, Jun 16, 2004 at 09:24:50PM -0400, Eric B. Ridge wrote:
> Okay, we finally broke down and write a quickie threaded test in C++ to
> reproduce the database problems we've been having.  On my dual-processor Mac
> running OS X, this test fails every time.
> 
> The code is below, and should be fairly straight forward.  1 writer thread
> that constantly add's documents to a Xapian::WritableDatabase, and a bunch
> of reader threads that execute queries.

Great - this should be very helpful.

> Reader:  ERROR=Error reading all bytes: Bad file descriptor (fd=7)

That's very odd.  That's either a Btree base file, or the meta file.

> Reader:  ERROR=Error reading block 40: Bad file descriptor (fd=5)

And a DB file this time.

> Writer:  flush()
> Reader:  ERROR=Db block overwritten

That's less odd.  After the writer has flushed twice, readers will get
this exception - they need to call reopen() and restart the operation.

> Writer:  ERROR=Db block overwritten

But the writer thread shouldn't get this unless there's another writer.

> Any ideas?  We wrote this little C++ test pretty quickly (could be buggy),
> but it reproduces what we're seeing from the Java-side.

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.

Cheers,
    Olly