enabling thread safety for NTL

[edgarcosta]

This ticket tries to enable threads in the NTL build, as suggested in #27764.

4 years ago, as of the NTL upgrade ticket #20590, we weren't ready to have NTL built with thread safety because of a lack of support for c++11. (On that ticket, it was noted "we cannot take advantage of the threading until a number of things are resolved. Threading requires C++11 and a number of packages are behind the curve.")

What about now?

########## thread safety

NTL_THREADS=on

# Set to 'on' if you want to compile NTL in thread-safe mode.  This requires
# several C++11 features, including atomic types, mutexes, and thread_local
# storage.  Your compiler may not yet support these features.  Setting this
# flag will automatically set the NTL_STD_CXX11 flag (if neither NTL_STD_CXX11
# or NTL_STD_CXX14 is already set). It will also pass -pthread throught to the
# compiler via CXXAUTOFLAGS (if possible).

Also do we need to change any cython files? For example, add something like:
# distutils: extra_compile_args = -std=c++11?

CC: @kiwifb @jpflori @dimpase @mwageringel @antonio-rojas

Component: packages: standard

Author: Edgar Costa

Branch/Commit: u/edgarcosta/threadsafe @ de7c0fc

Issue created by migration from https://trac.sagemath.org/ticket/29267

[edgarcosta]

Author: Edgar Costa

[videlec]

comment:2

According to our documentation, we support gcc 4.8 in which c++ 11 support is experimental. If NTL does not automatically pick-up the correct configuration with old gcc, this is an upstream bug. However, this ought to be tested.

[videlec]

comment:3

As mentioned in the ticket description, it would be good to have the docutils directive in the Cython headers for ntl. src/libs/src/sage/libs/ntl/types.pxd should be enough.

[mkoeppe]

comment:4

Needs rebasing

[mkoeppe]

comment:5

As noted on duplicate ticket #29340:

Enabling threads in NTL will require work on at least the following:

• Singular - at least on homebrew (see Fix NTL spkg-configure.m4 so it rejects NTLs built with NTL_THREADS #29339/Add to tox.ini some homebrew toxenvs (with a fresh install not in /usr/local), add homebrew packages #29104).
• Flint - see configure threading in flint in sync with NTL #27764

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

0e0bd5f

add extra flags

[sagetrac-git]

Changed commit from b858504 to 0e0bd5f

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

2c2f57d	enabling NTL threadsafe
de7c0fc	add extra flags

[sagetrac-git]

Changed commit from 0e0bd5f to de7c0fc

[edgarcosta]

comment:8

I have rebased on top of develop and added # distutils: extra_compile_args = -std=c++11 to src/libs/src/sage/libs/ntl/types.pxd.

[mkoeppe]

comment:9

Tests run at https://github.com/mkoeppe/sage/actions/runs/62362311

[mkoeppe]

comment:10

Batch modifying tickets that will likely not be ready for 9.1, based on a review of the ticket title, branch/review status, and last modification date.

[mkoeppe]

comment:12

Sage development has entered the release candidate phase for 9.3. Setting a new milestone for this ticket based on a cursory review of ticket status, priority, and last modification date.

[mkoeppe]

comment:13

Setting a new milestone for this ticket based on a cursory review.

[mkoeppe]

comment:14

Stalled in needs_review or needs_info; likely won't make it into Sage 9.5.