[erlang-questions] why is mmap so darn difficult

Tim Watson <>
Wed Jun 12 19:44:41 CEST 2013


Hi Max,

On 12 Jun 2013, at 10:43, Max Lapshin wrote:

> Of course, you will not be able to handle such load with mmap, because
> you will suffer from blocking whole VM on mmap page faults.
> 

Yes of course you're right about that, with mmap running in a NIF. I attempted to use both emmap and the mmap driver you wrote for erlyvideo and found the resulting behaviour highly variable.

> Add more async threads and profile application. Don't waste your time on mmap.

I'm starting to wonder whether attempting to provide very high speed concurrent reads + writes in Erlang is going to work at all. I might spend some time looking at lmdb instead, since it claims some extremely high numbers. I was hoping to avoid writing a driver though, but ho hum...

Cheers,
Tim


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