I'm using Git 1.8.0-rc2 and cvs2git version 2.5.0-dev (trunk). The
repository is almost 20 years old and should consist of mostly
smallish plain text files. We've been tagging every commit, in
addition to for releases and development branches, so there's a lot of
tags and branches. I didn't see the memory usage of the process before
exiting but after ~3.5 hours in a subsequent run it seems to be using
about 8.5GB of virtual memory with a resident size of only .5GB, which
should have easily fit on the 512GB machine that I was using. I'm
trying on a 1TB machine now but it doesn't look like it'll make a
difference. There is no ram disk and I have exclusive access to the
machine so only from the OS, which is trivial. The only significant
limit from my environment would be on the stack:
[umoszkow@mawhp5 ~] limit
stacksize 8000 kbytes
coredumpsize 0 kbytes
memorylocked 32 kbytes
Would that result in an mmap error though? I'll try with unlimited
stacksize and descriptors anyway.
I don't think modifying the original repository or a clone of it is
possible at this point but breaking up the import into a few steps may
be - will try that next if this fails.
On Tue, Oct 16, 2012 at 2:18 AM, Michael Haggerty <mhag...@alum.mit.edu> wrote:
> On 10/15/2012 05:53 PM, Uri Moszkowicz wrote:
>> I'm trying to convert a CVS repository to Git using cvs2git. I was able to
>> generate the dump file without problem but am unable to get Git to
>> fast-import it. The dump file is 328GB and I ran git fast-import on a
>> machine with 512GB of RAM.
>> fatal: Out of memory? mmap failed: Cannot allocate memory
>> fast-import: dumping crash report to fast_import_crash_18192
>> error: git-fast-import died of signal 11
>> How can I import the repository?
> What versions of git and of cvs2git are you using? If not the current
> versions, please try with the current versions.
> What is the nature of your repository (i.e., why is it so big)? Does it
> consist of extremely large files? A very deep history? Extremely many
> branches/tags? Extremely many files?
> Did you check whether the RAM usage of git-fast-import process was
> growing gradually to fill RAM while it was running vs. whether the usage
> seemed reasonable until it suddenly crashed?
> There are a few obvious possibilities:
> 0. There is some reason that too little of your computer's RAM is
> available to git-fast-import (e.g., ulimit, other processes running at
> the same time, much RAM being used as a ramdisk, etc).
> 1. Your import is simply too big for git-fast-import to hold in memory
> the accumulated things that it has to remember. I'm not familiar with
> the internals of git-fast-import, but I believe that the main thing that
> it has to keep in RAM is the list of "marks" (references to git objects
> that can be referred to later in the import). From your crash file, it
> looks like there were about 350k marks loaded at the time of the crash.
> Supposing each mark is about 100 bytes, this would only amount to 35
> Mb, which should not be a problem (*if* my assumptions are correct).
> 2. Your import contains a gigantic object which individually is so big
> that it overflows some component of the import. (I don't know whether
> large objects are handled streamily; they might be read into memory at
> some point.) But since your computer had so much RAM this is hardly
> 3. git-fast-import has a memory leak and the accumulated memory leakage
> is exhausting your RAM.
> 4. git-fast-import has some other kind of a bug.
> 5. The contents of the dumpfile are corrupt in a way that is triggering
> the problem. This could either be invalid input (e.g., an object that
> is reported to be quaggabytes large), or some invalid input that
> triggers a bug in git-fast-import.
> If (1), then you either need a bigger machine or git-fast-import needs
> architectural changes.
> If (2), then you either need a bigger machine or git-fast-import and/or
> git needs architectural changes.
> If (3), then it would be good to get more information about the problem
> so that the leak can be fixed. If this is the case, it might be
> possible to work around the problem by splitting the dumpfile into
> several parts and loading them one after the other (outputting the marks
> from one run and loading them into the next).
> If (4) or (5), then it would be helpful to narrow down the problem. It
> might be possible to do so by following the instructions in the cvs2svn
> FAQ  for systematically shrinking a test case to smaller size using
> destroy_repository.py and shrink_test_case.py. If you can create a
> small repository that triggers the same problem, then there is a good
> chance that it is easy to fix.
> (the cvs2git maintainer)
>  http://cvs2svn.tigris.org/faq.html#testcase
> Michael Haggerty
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