[issue1988] shared clones do not share branch head cache

[Greg Ward]

New submission from Greg Ward <greg-hg at gerg.ca>:

With large repositories, rebuilding the branch head cache can take quite a 
while (30 sec in my case).  And that happens whenever you strip or rollback; 
rollback can be frequent when you have a pretxncommit hook watching your 
every move.

Now imagine you are maintaining 11 active branches with 11 shared clones and 
you rollback in one of them.  (Or your nasty hook rolls back for you.)  The 
next operation in *every* shared clone will rebuild the branch head cache, 
even though they all have the same repository.   So it ends up taking 11x 
longer to do whatever-it-is-you-were-doing than it really ought to take.  
Yuck.

Incidentally, this also affects the tag cache.  But rebuilding the tag cache 
is much less expensive, especially if you have a small number of heads.

----------
messages: 11479
nosy: gward
priority: feature
status: unread
title: shared clones do not share branch head cache
topic: performance

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