It's also not too hard to DIY: http://www.dr-josiah.com/2012/01/creating-lock-with-redis.html http://www.dr-josiah.com/2012/01/creating-lock-with-redis.ht...

It's also not too hard to DIY: http://www.dr-josiah.com/2012/01/creating-lock-with-redis.html http://www.dr-josiah.com/2012/01/creating-lock-with-redis.ht... https://github.com/njbooher/boglab_tools/blob/dece35f13a8fcb9cb5b7eefdee2d6f9916350918/entrez_cache.py#L105 https://github.com/njbooher/boglab_tools/blob/dece35f13a8fcb... When multiple processes ask this for the same file one of them downloads it and the others wait for it to finish.