Trac #31344: homebrew: docbuild crashes, libtcl AtForkPrepare - from …

…sage.misc.cython globals / multiprocessing

(from #31335, reported in https://groups.google.com/g/sage-
devel/c/9EMs9h2i_H4)

URL: https://trac.sagemath.org/31344
Reported by: mkoeppe
Ticket author(s): Matthias Koeppe, John Palmieri
Reviewer(s): John Palmieri

src/sage/misc/cython.py

@@ -31,20 +31,31 @@
 from sage.repl.user_globals import get_globals
 from sage.misc.sage_ostools import restore_cwd, redirection
 from sage.cpython.string import str_to_bytes
+from sage.misc.cachefunc import cached_function
 
-cblas_pc = pkgconfig.parse(get_cblas_pc_module_name())
-cblas_libs = list(cblas_pc['libraries'])
-cblas_library_dirs = list(cblas_pc['library_dirs'])
-cblas_include_dirs = list(cblas_pc['include_dirs'])
-
-standard_libs = [
-    'mpfr', 'gmp', 'gmpxx', 'pari', 'm',
-    'ec', 'gsl',
-] + cblas_libs + [
-    'ntl']
+@cached_function
+def _standard_libs_libdirs():
+    r"""
+    Return the list of libraries and library directories.
 
-standard_libdirs = [os.path.join(SAGE_LOCAL, "lib")] + cblas_library_dirs
+    EXAMPLES::
 
+        sage: from sage.misc.cython import _standard_libs_libdirs
+        sage: _standard_libs_libdirs()
+        (['mpfr', 'gmp', 'gmpxx', 'pari', ...],
+         [...])
+    """
+    cblas_pc = pkgconfig.parse(get_cblas_pc_module_name())
+    cblas_libs = list(cblas_pc['libraries'])
+    cblas_library_dirs = list(cblas_pc['library_dirs'])
+    cblas_include_dirs = list(cblas_pc['include_dirs'])
+    standard_libs = [
+        'mpfr', 'gmp', 'gmpxx', 'pari', 'm',
+        'ec', 'gsl',
+    ] + cblas_libs + [
+        'ntl']
+    standard_libdirs = [os.path.join(SAGE_LOCAL, "lib")] + cblas_library_dirs
+    return standard_libs, standard_libdirs
 
 ################################################################
 # If the user attaches a .spyx file and changes it, we have
@@ -310,6 +321,7 @@ def cython(filename, verbose=0, compile_message=False,
                 '-Wl,--image-base=0x{:x}'.format(image_base)
         ])
 
+    standard_libs, standard_libdirs = _standard_libs_libdirs()
     ext = Extension(name,
                     sources=[pyxfile],
                     extra_compile_args=extra_compile_args,

src/sage_setup/docbuild/__init__.py

@@ -286,13 +286,15 @@ def clean(self, *args):
 
 from .utils import build_many as _build_many
 
-def build_many(target, args):
+def build_many(target, args, processes=None):
     """
     Thin wrapper around `sage_setup.docbuild.utils.build_many` which uses the
     docbuild settings ``NUM_THREADS`` and ``ABORT_ON_ERROR``.
     """
+    if processes is None:
+        processes = NUM_THREADS
     try:
-        _build_many(target, args, processes=NUM_THREADS)
+        _build_many(target, args, processes=processes)
     except BaseException as exc:
         if ABORT_ON_ERROR:
             raise
@@ -349,7 +351,13 @@ def _wrapper(self, name, *args, **kwds):
 
         # build the other documents in parallel
         L = [(doc, name, kwds) + args for doc in others]
-        build_many(build_other_doc, L)
+
+        # Trac #31344: Work around crashes from multiprocessing
+        if sys.platform == 'darwin':
+            for target in L:
+                build_other_doc(target)
+        else:
+            build_many(build_other_doc, L)
         logger.warning("Elapsed time: %.1f seconds."%(time.time()-start))
         logger.warning("Done building the documentation!")