[winswitch] xpra and distro support

[Antoine Martin]

Please always CC the mailing list.

On 06/06/16 11:58, Rolf Leggewie wrote:
> Hello,
> 
> thank you for providing xpra.  I've long hoped to be able to have a "GNU
> screen for X" and xpra promises to deliver that.  I've tried for a few
> years from time to time, but sadly xpra never delivered for me as a
> user.  If I always were compiling the latest upstream from scratch that
> might be different.  It's not that I can't do this (I'm a Debian
> Maintainer), but that I don't run gentoo for a reason.
> 
> I have the impression that xpra is constantly and rapidly evolving
> without sufficient concern for long-term stability.  This might be fine
> if you are only concerned with people compiling from source.  But for
> distributions you need a horizon of  several years.
We have an LTS version, supported for years. What downstream decides to
use is not up to us. For details, see:
http://xpra.org/trac/wiki/Building

> So, here is my story.  My first attempt to use xpra was fraught with
> severe stability issues as reported in
> https://bugs.launchpad.net/ubuntu/bugs/1159871.  I was running the
> latest long-term support, stable release of Ubuntu at the time which had
> been released less than a year prior.  Nonetheless, I was told by the
> Debian maintainer that I was using a "very old version of xpra".  The
> problem itself wasn't looked into.  At the time, xpra was very young at
> version 0.0.7 and that might be excusable.  I backported the package
> from unstable, the problem remained and was still not looked into.
Fixed link:
https://bugs.launchpad.net/ubuntu/+source/xpra/+bug/1159871
This ticket contains a number of issues, most of which I remember fixing
a long time ago. The proxy-start one just looks wrong though.
Things that aren't reported upstream may not get fixed in a timely manner.

> After several years, I tried again.  Of course, I am still running LTS
> because I have other things to do than having a constant headache about
> random bleeding edge software bringing my computer down and consuming my
> time.  I'm sure you understand.  I connected from a fully updated Ubuntu
> trusty machine to an equally fully updated Raspbian Jessie machine.  The
> Raspbian machine would go to 100% CPU for the xpra process on the
> simplest of tasks like hitting enter in xterm which I reported as a bug
> to Debian.  The ticket was closed immediately as "you are using ancient,
> unsupported software".  IMO, this means xpra should not even be part of
> a distribution since it's not supported for the full cycle of a
> release.  In fact, it's deemed "ancient" shortly after release of a
> distro.  I don't think this is what you as upstream want.
As per above: this is a question for downstream. From our end, we simply
do not have the manpower to support those outdated versions.

> I did not give up and looked into backporting newer releases again. 
> Then I found out that you are not releasing the source code for your
> binary packages.  That's a GPL violation.  Please kindly fix that. 
That's incorrect: every single line of source code and the patches
required to workaround Debian quirks (libav, headers, etc) are available
for download and documented. See:
http://xpra.org/trac/wiki/Building
We will not provide all-in-one source bundle archives for every
combination of version and distro out there. Nobody does, and this is
not required by the GPL either.

> What's more troublesome and the strongest motivator for this mail is
> that apparently you broke backward compatibility without documenting it
> and generally giving it much concern.  As you can see in
> https://bugs.debian.org/805751 and
> https://bugs.launchpad.net/bugs/1589336 apparently there is xpra 0.15.0
> and later versus prior versions.  Those two camps cannot talk to each
> other, period.  The prior versions include fairly recent stable releases
> of Debian and Ubuntu.  If there is something you can do now to have
> these two groups talking to each other again, that would be fantastic. 
Again, IIRC, this bug was fixed a long time ago.
I doubt this is still a problem with any supported version.

That said, most of the testing is done using the python client with
rencode (except the HTML5 client which uses bencode) - so issues like
this one may go unnoticed from time to time.
Again, we don't have the manpower to test every combination of every
supported version and every distro + architecture out there (each with
different combinations of installed recommends / suggests dependencies).

> At the very minimum, xpra should emit an error message if the opposite
> end is older and incompatible.
It does already. This is something else.

> Last, apparently you forgot to include python-rencode as a depends in
> your binary packages, even though that doesn't fully prevent problems
> related to it.
python-rencode is a hard dependency since v0.15.x which dropped support
for older distros. It isn't a hard dependency in v0.14.x and earlier
because many of the older distros do not have python-rencode at all, and
xpra still works fine without it, just a little bit more slowly.

> Once again, thank you for your work on xpra.

Cheers
Antoine

> 
> Regards
> 
> Rolf Leggewie
>