Re: 7-Zip / Bzip2

[Oliver Fromme <check+k0l9wf00rs3fwup1@xxxxxxxxxx>]

thegraze <thegraze@googlemail.com> wrote:
 > But 7z is GPL!

Which is not an impediment per-se.  After all it's just a
userland tool, not a library or even part of the kernel.
Remember that gzip was GPL for a long time, before the
NetBSD people started writing a replacement tool.

On the other hand, it should be noted that both bzip2 and
gzip (at least the one used by the BSDs) are now under BSD
licenses.  Replacing a BSD-licensed piece of software with
a GPL-licensed one is only desirable if the latter is much
more useful or has features that are needed, and if there
are good reasons to have it in base instead of pkgsrc.

So, is 7z useful enough to add a fourth compression tool
to the base system?  And keep it there forever?  (Remember
that we also have to keep compress(1) for compatibility,
even though it compresses worse and is slower than gzip,
so the usefulness is very small.)

I've given it a quick test and fed a 1 MB logfile to 7z.
It was only marginally better than bz2 (< 1%), but it was
noticeably slower.  And bz2 is already painfully slow for
both compression and decompression.  Not everybody has a
3 GHz multicore machine.  That's why I still use gzip most
of the time -- the compression is a little worse, but it's
a *lot* faster.

There were even cases when people reported that they
weren't able to decompress a bz2 file on a small system
(embedded or otherwise), because it required several
MB of RAM for decompression.  It appears that 7z is even
worse.  The memory footprint of gunzip is negligible.

It should also be mentioned that about every other year
another compression tool pops up that claims to be better
than all the others.  Last year (or the year before) it
was "paq", before that it was rzip and lrzip, and so on.
So this year it is 7z.  What will be the next one?

So, my personal opinion is:  Leave 7z in pkgsrc.

Just my 2 cents ...

Best regards
   Oliver

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