Performance on Windows JDK 8 2-3x slower

[juji-io]

Performance on Windows JDK 8 2-3x slower

[huahaiy]

Thank you very much for including Datahike in the benchmark and reporting this performance issue with Windows. I would appreciate if you could update your reddit post to include your Ubuntu run numbers also. More data points help everyone. I will investigate the problem when I get hold of a Windows machine.

[joinr]

No problem. Updated in reddit thread and on the datalevinbench repo README.

[huahaiy]

Thank you. @joinr I appreciate it.

[huahaiy]

It may not be a performance issue. Please take a look at joinr/datalevinbench#2

[joinr]

That was it indeed. The assumption about the temp file directory, /tmp, doesn't hold on Windows. This led to an ever growing database. The interesting news is that a db about 13x the size was still reading about 3x slower than the datascript. With a fresh db, the results conform to your reported baseline. No problem with lmdb on windows, just tempfile expectations :)

I added new-db to the benchmark to delete the old db (similar to what datahike is doing), which technically adds a little to the measurements, but the results are apparently identical (e.g. deletion isn't a problem). The "real" fix would be to implement a portable temp file pathway for the db (I think the storage/open function called with nil directory creates a tmp/uuid file, so that would probably be the only place to define a wrapper that leverages (System/getProperty "java.io.tmpdir") to construct a portable temp directory.

[joinr]

Updated reddit thread and readme for posterity.

[huahaiy]

Great. Thanks!