D5296: store: don't read the whole fncache in memory
Yuya Nishihara
yuya at tcha.org
Mon Feb 25 22:01:15 EST 2019
(resend without the "On ... wrote:" line)
> Seeing the performance benefit it brings on our repo, I want to try other ways we can do this. Do we like having a conditional which checks the size of fncache and choose one of the approaches depending on how large it is?
>
> If size(fncache) < 50M, use the current approach
> else, use the approach described in this patch
Suppose the current code is fast because it avoids running Python in loop,
I think it can be extended to not use too much memory.
```
chunk = b''
while True:
chunk += fp.read(chunk_size) # maybe ~10MB?
p = chunk.rindex(b'\n') # need to handle error
decodedir(chunk[:p + 1])...
chunk = chunk[p + 1:]
```
Just an idea. Not profiled.
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