Test multiple PARI versions

[jdemeyer]

We should test:

• PARI 2.8.1 (the oldest version supported)
• PARI 2.9.3 (latest stable)
• PARI master

[jdemeyer]

@videlec Please review, it would be good to include this too in the next cypari2 release.

[videlec]

What is the 2.8.beta version that is tested at https://travis-ci.org/defeo/cypari2/builds/266930844?

It would be better to do bash -x .travis-install-pari.sh to actually see the executed commands.

[videlec]

travis is supporting caching: https://docs.travis-ci.com/user/caching/. Using it would significantly speed up pari download and compilation. Though I am not sure if a different cache is automatically used for each environment.

[jdemeyer]

What is the 2.8.beta version that is tested at https://travis-ci.org/defeo/cypari2/builds/266930844

Ask upstream, seriously. They have a strange version numbering scheme.

[jdemeyer]

Using it would significantly speed up pari download and compilation

For compilation, we could use ccache indeed.

For downloads, Travis CI documents that this is not the intended use of caching: https://docs.travis-ci.com/user/caching/#Things-not-to-cache

[jdemeyer]

I tried to setup ccache, but I'm not entirely sure that it works. In any case, this shouldn't prevent this PR from being merged.

[videlec]

It should work, though we won't notice a difference on the first build...

[videlec]

It would be cleaner to have two environment variables PARI_VERSION PARI_URL instead of a if/else statement and a for loop in the script.

[jdemeyer]

It would be cleaner to have two environment variables PARI_VERSION PARI_URL instead of a if/else statement and a for loop in the script.

I don't know how you would do that, but feel free to implement it.

[jdemeyer]

Caching seems to work now.

[videlec]

One good thing would actually be to activate ccache for PARI compilation but disable it for cypari2. These are big useless C and .so files that you do not want to keep.

[jdemeyer]

These are big useless C and .so files that you do not want to keep.

Why that? ccache can also speed up compilations of Cython-generated C files.

[videlec]

I tried a simpler script version on the branch test_pari_versions-bis

[videlec]

These are big useless C and .so files that you do not want to keep.

Why that? ccache can also speed up compilations of Cython-generated C files.

I was worried about the cache limit being set to 256M. With a quick du -sh

• PARI is 187M
• cypari2 is 41M

[videlec]

In Travis, do you know why does $ pip install --verbose -r requirements.txt takes so long (~3 min)?

[jdemeyer]

In Travis, do you know why does $ pip install --verbose -r requirements.txt takes so long (~3 min)?

Cython takes a while to compile because it uses itself to compile itself to C. And cysignals also uses Cython, so it also needs to be compiled. But ccache should help here...

[jdemeyer]

I tried a simpler script version on the branch test_pari_versions-bis

See #32

[jdemeyer]

I was worried about the cache limit being set to 256M.

First of all, the limit can be changed. Second, it seems that the cache is only a bit over 100MB, so 256MB should be large enough.

[jdemeyer]

If Cython needs to be compiled then 256M is definitely a too low limit for ccache.

Why do you think so? Look at the build logs, you see something like

cache directory                     /home/travis/.ccache

cache hit (direct)                     0

cache hit (preprocessed)               0

cache miss                           170

called for link                       55

called for preprocessing               8

bad compiler arguments                 1

autoconf compile/link                  8

no input file                          5

files in cache                       205

cache size                         125.3 Mbytes

max cache size                     256.0 Mbytes

[jdemeyer]

I just realized that caching might not work properly with pip install because it uses a random temporary directory which changes every time. I'll try to fix this

See also https://ccache.samba.org/manual.html#_compiling_in_different_directories

[videlec]

I just realized that caching might not work properly with pip install because it uses a random temporary directory which changes every time. I'll try to fix this

Don't the --build option of pip would settle that problem?

-b, --build <dir>           Directory to unpack packages into and build in.

[videlec]

(not sure pypa/pip#4262)

[videlec]

But travis does support pip cachig (https://docs.travis-ci.com/user/caching/)

language: python

cache: pip

[jdemeyer]

Don't the --build option of pip would settle that problem?

In theory, yes. In practice, it doesn't actually seem to work: pypa/pip#4242

[jdemeyer]

Hmm, the actual issue might be pypa/pip#804