Re: Using lzip instead of xz for distributed tarballs

On January 21, 2020 11:44:15 AM EST, Vanessa McHale wrote:

Would it be plausible to distribute both? That way users would not have to install lzip.

Cheers, Vanessa McHale

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On Jan 20, 2020, at 4:15 PM, Ben Gamari wrote:

Vanessa McHale writes:

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Hello all,

GHC is distributed as .tar.xz tarballs; I assume this is because it produces small tarballs. However, xz is ill-suited for archiving due to its lack of error recovery. Moreover, lzip produces smaller tarballs with GHC (I tested with ghc-8.8.2-x86_64-deb9-linux.tar) and decompression takes about the same amount of time.

Indeed I recall seeing the "Why xz is not suitable for archival purposes" blog post quite a while ago and considered moving away from xz at the time but wasn't entirely convinced that the benefits would justify the churn, especially since xz tends to be pretty ubiquitous at this point while lzip is a fair bit less so.

I'd be happy to hear further reasons why we should switch but I'll admit that I still don't quite see what switching would buy us; we do have a few backups spread across the planet so the probability of us having to rely on the compressor for error recovery pretty small.

Cheers,

- Ben

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There is indeed precedent for this. IIRC, we distributed both bzip2 and xz tarballs for several years. I'm not opposed to offering both, the biggest cost is the storage and that is relatively minor. I have opened #17726 to track this. Cheers, - Ben