Memoize a few hot functions during module file generation (#37739)

5 files changed, 16 insertions, 13 deletions

diff --git a/lib/spack/spack/modules/common.py b/lib/spack/spack/modules/common.py
index 278038510a..ef3f751471 100644
--- a/lib/spack/spack/modules/common.py
+++ b/lib/spack/spack/modules/common.py
@@ -170,11 +170,9 @@ def merge_config_rules(configuration, spec):
     Returns:
         dict: actions to be taken on the spec passed as an argument
     """
-    # Construct a dictionary with the actions we need to perform on the spec passed as a parameter
-    spec_configuration = {}
     # The keyword 'all' is always evaluated first, all the others are
     # evaluated in order of appearance in the module file
-    spec_configuration.update(copy.deepcopy(configuration.get("all", {})))
+    spec_configuration = copy.deepcopy(configuration.get("all", {}))
     for constraint, action in configuration.items():
         if spec.satisfies(constraint):
             if hasattr(constraint, "override") and constraint.override:
diff --git a/lib/spack/spack/modules/lmod.py b/lib/spack/spack/modules/lmod.py
index 64c8c49b7e..0abead05b6 100644
--- a/lib/spack/spack/modules/lmod.py
+++ b/lib/spack/spack/modules/lmod.py
@@ -134,6 +134,7 @@ class LmodConfiguration(BaseConfiguration):
         return configuration(self.name).get("filter_hierarchy_specs", {})
 
     @property
+    @lang.memoized
     def hierarchy_tokens(self):
         """Returns the list of tokens that are part of the modulefile
         hierarchy. 'compiler' is always present.
@@ -158,6 +159,7 @@ class LmodConfiguration(BaseConfiguration):
         return tokens
 
     @property
+    @lang.memoized
     def requires(self):
         """Returns a dictionary mapping all the requirements of this spec
         to the actual provider. 'compiler' is always present among the
@@ -224,6 +226,7 @@ class LmodConfiguration(BaseConfiguration):
         return available
 
     @property
+    @lang.memoized
     def missing(self):
         """Returns the list of tokens that are not available."""
         return [x for x in self.hierarchy_tokens if x not in self.available]
@@ -317,6 +320,7 @@ class LmodFileLayout(BaseFileLayout):
         return parts
 
     @property
+    @lang.memoized
     def unlocked_paths(self):
         """Returns a dictionary mapping conditions to a list of unlocked
         paths.
@@ -428,6 +432,7 @@ class LmodContext(BaseContext):
         return self.conf.missing
 
     @tengine.context_property
+    @lang.memoized
     def unlocked_paths(self):
         """Returns the list of paths that are unlocked unconditionally."""
         layout = make_layout(self.spec, self.conf.name, self.conf.explicit)
diff --git a/lib/spack/spack/tengine.py b/lib/spack/spack/tengine.py
index 86c5235a57..6a77e6becf 100644
--- a/lib/spack/spack/tengine.py
+++ b/lib/spack/spack/tengine.py
@@ -4,7 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import itertools
 import textwrap
-from typing import List
+from typing import List, Optional, Tuple
 
 import llnl.util.lang
 
@@ -66,17 +66,17 @@ class Context(metaclass=ContextMeta):
         return dict(d)
 
 
-def make_environment(dirs=None):
-    """Returns an configured environment for template rendering."""
+@llnl.util.lang.memoized
+def make_environment(dirs: Optional[Tuple[str, ...]] = None):
+    """Returns a configured environment for template rendering."""
+    # Import at this scope to avoid slowing Spack startup down
+    import jinja2
+
     if dirs is None:
         # Default directories where to search for templates
         builtins = spack.config.get("config:template_dirs", ["$spack/share/spack/templates"])
         extensions = spack.extensions.get_template_dirs()
-        dirs = [canonicalize_path(d) for d in itertools.chain(builtins, extensions)]
-
-    # avoid importing this at the top level as it's used infrequently and
-    # slows down startup a bit.
-    import jinja2
+        dirs = tuple(canonicalize_path(d) for d in itertools.chain(builtins, extensions))
 
     # Loader for the templates
     loader = jinja2.FileSystemLoader(dirs)
diff --git a/lib/spack/spack/test/relocate.py b/lib/spack/spack/test/relocate.py
index 1b14ad9fbb..a0553d4422 100644
--- a/lib/spack/spack/test/relocate.py
+++ b/lib/spack/spack/test/relocate.py
@@ -62,7 +62,7 @@ def source_file(tmpdir, is_relocatable):
         src = tmpdir.join("relocatable.c")
         shutil.copy(template_src, str(src))
     else:
-        template_dirs = [os.path.join(spack.paths.test_path, "data", "templates")]
+        template_dirs = (os.path.join(spack.paths.test_path, "data", "templates"),)
         env = spack.tengine.make_environment(template_dirs)
         template = env.get_template("non_relocatable.c")
         text = template.render({"prefix": spack.store.layout.root})
diff --git a/lib/spack/spack/test/tengine.py b/lib/spack/spack/test/tengine.py
index 3ade233160..95362c33fa 100644
--- a/lib/spack/spack/test/tengine.py
+++ b/lib/spack/spack/test/tengine.py
@@ -71,7 +71,7 @@ class TestTengineEnvironment(object):
         """Tests the template retrieval mechanism hooked into config files"""
         # Check the directories are correct
         template_dirs = spack.config.get("config:template_dirs")
-        template_dirs = [canonicalize_path(x) for x in template_dirs]
+        template_dirs = tuple([canonicalize_path(x) for x in template_dirs])
         assert len(template_dirs) == 3
 
         env = tengine.make_environment(template_dirs)