PoC AppImage? about appimage-runtime HOT 5 CLOSED

Hello @tim-janik, this is very interesting work.
Is there a proof-of-concept AppImage for download?

I'm mainly working on this for Anklang, and that still needs some work before I can put up release candidates.
But appimage-runtime-zstd works exactly like the AppImage runtime, so just concatenating any AppImage squashfs image will get you a PoC.

I'd be especially interested in how it works on FUSE3-only systems, where our current AppImage runtime seemingly refuses to run.

Yeah, that's because the current AppImage runtime has a dynamic library dependency on libfuse.
I just tried appimage-runtime-zstd inside a docker image of the latest Fedora:

docker run --rm -ti --device /dev/fuse --privileged -v /.../anklang/out/:/out fedora:35
# dnf install some-ui-libs...
# /out/anklang-0.0.1-alpha0-x64.AppImage --no-sandbox --help
Usage: anklang [OPTIONS] [--] [ProjectFiles...]
# find / -iname libfuse\*
#

The fedora:35 docker image has no libfuse version installed whatsoever.
So the statically linked libfuse in appimage-runtime-zstd simply uses the ioctl kernel interfaces.

Are you aware of https://github.com/mensinda/libRuntime? It seems to go into a similar direction.

Not yet, I'll take a look if that adds any significant improvements to the original AppImage runtime.

BTW, the reason there is a appimage-runtime-zstd in the first place is that I've run benchmarks with all the compression formats supported by mksquashfs. The bottom line is, unless you are happy with compression ratios much worse than gzip, there is no point in going for anything other than zstd. At any useful compression ratio (and zstd compresses better than gzip), zstd usually beats the other supported compression libraries in terms of speed, particularly for decompression which determines the AppImage execution performance.

from appimage-runtime.

Do you think the zstd runtime should become the default in AppImageKit? Do you see any significant downsides?

from appimage-runtime.

Do you think the zstd runtime should become the default in AppImageKit? Do you see any significant downsides?

I'd definitely make zstd the default, but:

1. libzstd is significantly larger than libz. So for small squashfs AppImages, where size matters more than speed, using a different compression scheme can make sense. For reference, here are the sizes on my Ubuntu-20.04:

-rw-r--r-- 1 root root 107K Okt 15  2020 /lib/x86_64-linux-gnu/libz.so.1.2.11
-rw-r--r-- 1 root root 671K Mär  3  2021 /usr/lib/x86_64-linux-gnu/libzstd.so.1.4.4

2. I haven't attempted to build libzstd on really old distributions like CentOS-6, I'm currently simply building on Ubuntu-20.04. On 2021-06-09 @TheAssassin and I had a brief discussion in #AppImage about this:

(22:55:10) TheAssassin: have you tried 18.04 tho?
(22:58:45) timj: i think 18.04 would be doable with a few more days, at least for the runtime. i think it was squashfs-dev or fuse-dev that was missing of the shelf compared to 20.04. so that'd involve building those libs yourself... Once you go down that route, it also makes sense to build zstd from scratch and disable as much mksquashfs+compression code as possible that way, so the runtime can be shrunk down to only include decompression code.

from appimage-runtime.

@tim-janik I agree, I did some tests recently and zstd is a much better default than gzip for any compatible system, effectively being able to replace both gzip and xz with much faster performance (albeit slightly bigger binaries than xz)

For small AppImages, maybe LZ4 should be used as default (automatic detection and switch at a certain threshold unless the user says otherwise)? I would still get near 50% compression in my tests, and the launch penalty was practically zero because of LZ4's low CPU cost. It's also an incredibly small library so it wouldn't bloat the runtime

from appimage-runtime.

Is there a proof-of-concept AppImage for download?

BTW, there is a pre-release of Anklang out now, that uses appimage-runtime-zstd:
https://github.com/tim-janik/anklang/releases/tag/v0.0.1-alpha1

from appimage-runtime.