Re: [Lzip-bug] bug report: 'plzip -vf9' fails to compress files over a certain size

[Erik Jan Tromp]

On Sun, 10 Dec 2017 20:37:27 +0100
Antonio Diaz Diaz <address@hidden> wrote:

Hi Antonio,

Thanks for the quick response!

> > Tests were also performed on the following hardware using 'plzip -vf9
> > foo.tar' with no errors.
> 
> All of them seem to either be 64 bit or have too few processors to reach 
> the per process memory limit of 32 bit. Am I wrong?

I believe you're correct (re: per process limit). The atom n270 is a 32
bit cpu, the other 4 are 64 bit cpus. All are running Slackware 14.2 32
bit.

> > Please note that while specifying '-n' & '-s' options are functional
> > solutions, they are unacceptable for the intended use case. Regardless
> > of a machine's hardware, the resulting compressed files must be
> > identical/predictable.
> 
> If you want identical results on 32 and 64 bit machines, I guess you'll 
> need to limit the number of threads. Limiting the dictionary size may 
> not be enough on 32 bit systems with many cores.

I had assumed (& hoped) plzip would attempt to use as much ram as
possible, scale back the number of threads if/when necessary, then
throw an error only if there was insufficient memory for a single
thread.

Please consider this a feature request. :)

I've come up with a (hopefully temporary) hack that works on the i7 (&
the others). It's essentially what I mentioned above: if an error
occurs with '-vf9', loop through '-vf9 -n8' to '-vf9 -n1' until
compression succeeds or the last attempt fails.

Vriendelijke groeten,
Erik

-- 
If you want to improve, be content to be thought foolish and stupid.
 -- Epictetus