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Re: [Question #191807]: what about using mmap?

To: graphite-dev@xxxxxxxxxxxxxxxxxxx
From: Amos Shapira <question191807@xxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 27 Mar 2012 06:20:48 -0000
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Question #191807 on Graphite changed:
https://answers.launchpad.net/graphite/+question/191807

Description changed to:
I read in one of the answers (comment #4 in https://answers.launchpad.net/graphite/+question/170794) that carbon-cache keeps writing to both the first and last blocks of each .wsp file.
This means that it has to keep doing lseek+read+write system calls  every time it updates the file.
I'm not very familiar with Python but a quick search tells me that it supports mmap (http://docs.python.org/library/mmap.html).
Using mmap(2) could give a huge advantage:
1. No system calls (which are expensive).
2. No copying of data between the process user-space and kernel buffers on each read/write

What do you say?

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