Re: [gentoo-user] xz memory hungry?

[Florian Philipp <lists@binarywings.net>]

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Am 22.08.2012 22:32, schrieb Jorge Almeida:
> On Wed, Aug 22, 2012 at 8:05 PM, Michael Mol <mikemol@gmail.com> wrote:
>> On Wed, Aug 22, 2012 at 2:52 PM, Jorge Almeida <jjalmeida@gmail.com> wrote:
>>> # tar -xJvf /usr/portage/distfiles/m4-1.4.16.tar.xz
>>> xz: (stdin): Cannot allocate memory
>>>
>>> The box has 2G ram + 1G swap. I'm installing Gentoo from an existing distro.
>>
>> How much do you have free? From xz's manpage:
> 
> Almost all of it! It's a one-user workstation, which was essentialy idle.
>>
>>
> I read the man page of xz, but it suggested nothing to me.
>>
>> Three things come to mind:
>>
>> 1) You may not have enough memory free
>> 2) There may be a bug (either compile/link-induced or code-induced) in
>> the copy of xz you're using
>> 3) Upstream used some insane settings, causing a massive increase in
>> the amount of RAM required to decompress that stream.
>>
>>
>> You could download the .tar.xz file, decompress it on a different box,
>> and then recompress it with lighter settings.
>>
>> unxz filename.tar.xz
>> xz -1 filename.tar
>>
> Done that. It extracts now,  so 3) is the correct hypothesis, and  "insane" is
> really the appropriate word. Of course, the hash digests are now wrong, so
> emerge still fails. Any idea how to find which amount of memory is needed? I
> would setup appropriate swap, if possible. [...]

There is a table in `man xz` showing the memory requirements. Even with
the highest setting, you only need 65 MB memory for decompression (674
MB for compression, though).

Regards,
Florian Philipp


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