[Success!] Re: [MERGE][1.6.1] 1.6 fetch regression

[John Arbash Meinel]

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David Ingamells wrote:
> What are the plans for the 1.6.1 branch? Possible release dates?
> 
> I'd like to move our team up to a release of 1.6 with John Arbash
> Meinel's branch performance fixes, but since this will be used by a
> large-ish team I will only upgrade if there is a release that has
> undergone the standard regression testing - no criticism of John's great
> work implied ;^). At worst I'll only need to wait for 1.7 ...

Oh, and I should mention. *every* commit to bzr.dev goes through the full 13+k
unit test regression suite.

This wasn't strictly a regression, just a change of code path which triggered
a latent issue in the other code. It only happened under the specific
permutation of Robert's new fetching algorithm allowing us to fetch
more-at-a-time, and the win32 patch causing us to read only 64kB from a
socket. (So we were fetching 10+MB in one request, but only reading and
buffering it 64kB at a time, causing us to reallocate the buffer far too often.)

It also only shows up on branching from-scratch because you are downloading
more of the repository, only really shows up for large projects, and only if
you are using bzr+ssh. (You need >1MB downloaded at a time before the effects
start to become severe, it just happens to be an O(N^2) problem with small
coefficients. So for most use it never was an issue, until you try to download
100+ MB at one time, and the quadratic term becomes a real issue. For 100MB we
would re-allocate ~1,600 times. So it is N*(N+1)/2 *64kB = 76GB of "churn".)

Anyway, you are welcome to pick your route. I hope to have 1.6.1 final before
1.7rc1 is released.

John
=:->

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