Allow for different settings for each thread when testing with --parallel

[Leonardo Arroyo]

I'm trying to run my tests in parallel and it mostly work fine, however, I'm testing an application which users haystack + whoosh and I end up getting a lock error from whoosh because multiple threads are trying to write to the same index.
It would be extremely useful if I could modify the settings for each thread, this way I can specify different whoosh indexes for each thread, much like django automatically handles multiple databases in parallel testing.

[Tom Forbes]

This seems pretty specific, a better idea might be to submit a change to the haystack library to support giving callable values in the settings (then you can return a different index value per thread)?

[Tim Graham]

Or maybe your test settings file could make use of ​threading.get_ident() to construct the index name? Like Tom, I'm also not immediately convinced that this would be generally useful. Feel free to to put together a proof of concept and write to the DevelopersMailingList to see what others think.

[Simon Charette]

I can't find the exact discussion (either here or on the mailing list) but this was discussed in the past. I think it was about using a different Redis databases per-process which is really similar to this issue.