"bzr check" in packs format takes more than 2GB RAM

I confirm that with 2a this doesn't happen: memory usage is then 900 MB. That's far less than 7GB, though 900MB is still quite a lot; I don't see well why so much memory is needed.
Anyway, I have the 1.14-repo check running now on a machine with 12GB RAM, for 24 hours already, and hope it will finish successfully.

So I have more results.
On my machine with 12GB RAM 4-core Linux I have two identical 1.14 shared repositories ("identical" as in "copied with cp -a"), I did "check -v" on one copy with bzr.dev, and on another copy with bzr 1.15.1.
* 1.15.1:
- "checking revisions" (87000 of them): took 24 hours
- "checking text storage: calculating text parents" (418000 of them): took 24 hours
- during those two phases, RAM usage was <6%
- then a few hours were spent in checking branches, RAM went to 50%
- the command terminated normally, taking in total 51 hours.
* bzr.dev:
- I killed it, out of patience, after 117 hours
- RAM usage was consistently 50% over all this time
- I cannot tell what the progress bar was saying, because I had redirected stdout to a file, and this makes the progress bar invisible.
* Note that the check with bzr.dev had been started 66 hours before the check with 1.15.1, so it's not a problem of parallel operations loading the machine. And there were no other significant operations on the machine for the whole time.

This seems to surely be a bug introduced between 1.15.1 and bzr.dev :-)
I suspect that you could reproduce this problem by creating a shared repo in 1.14 format, putting into it this branch:
https://code.launchpad.net/~mysql/mysql-server/mysql-6.0-codebase-bugfixing
and then running "bzr check -v". The above branch has the bulk of revisions of my shared repository.

Thanks, narrowing it down like that is helpful.

--
Martin <http://launchpad.net/~mbp/>

Quick experiments with different versions, on the same 1.14 repo as above:

bzr.dev, 1.18.1:
They first do a check of each branch (fast) then go into
 checking commit contents:inventories 0/2
After 11 mins RAM starts growing from 6% to 50% (i.e. 6GB...)
I do control-C and see that bzr is in:
> bzrlib/osutils.py(656)sha_strings()
-> map(s.update, strings)

1.15.1, 1.17:
Seem to do things differently:
No working tree found at specified location.
Checking repository at 'file:///home/mysql_src/from_bk_internal/guilhem/'.
[###############/ ] checking revision graph:Checking cached revision graph 53000/87653
then goes into a 24-hour-long
[\ ] checking revision 3/87653
where RAM stays <6%.

So possibly this RAM consumption is a bug introduced between 1.17 and 1.18.1. Now I'm letting this for you to look at :-)