[Melbourne-pm] Git correction

Toby Corkindale toby.corkindale at rea-group.com
Tue Jun 17 22:59:04 PDT 2008

Hey guys,
Just a quick correction to the talk I gave a month or so ago..

At the time, I mentioned that Git did seem to have a potential problem, 
with the garbage-collection pass not being multi-user safe.
(ie. If you ran it at the same time as someone else was modifying data, 
there was a potential race condition)

Since then I've looked into it more, and it seems that my research was 
looking at old information.
Git has been safe from this race condition for quite some time now.

The GC pass only removes things that look like garbage when they're 
older than a configurable amount of days.

The race condition *was* that someone could upload some packs for, say, 
a new branch, but then have them garbage-collected before the user had 
uploaded the references to them.

The default garbage age is now something like 60 days.. so in order for 
the race condition to occur, you'd have to be pushing at an insanely 
slow speed! (If your upload takes two months, maybe you should just post 
a CD :)

Of course this has then resulted in users acting confused because 
they're creating big branches, then deleting the branches, and wondering 
why their repo doesn't shrink at all after running git-gc.

Anyway, I just thought I'd drop the correction through.. I meant to 
mention it at the last meeting but forget :(


Toby Corkindale
Software developer
w: www.rea-group.com
REA Group refers to realestate.com.au Ltd (ASX:REA)

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