PERF: asv for import (#28239)

Author: jbrockmendel

asv_bench/benchmarks/package.py

@@ -0,0 +1,25 @@
+"""
+Benchmarks for pandas at the package-level.
+"""
+import subprocess
+import sys
+
+from pandas.compat import PY37
+
+
+class TimeImport:
+    def time_import(self):
+        if PY37:
+            # on py37+ we the "-X importtime" usage gives us a more precise
+            #  measurement of the import time we actually care about,
+            #  without the subprocess or interpreter overhead
+            cmd = [sys.executable, "-X", "importtime", "-c", "import pandas as pd"]
+            p = subprocess.run(cmd, stderr=subprocess.PIPE)
+
+            line = p.stderr.splitlines()[-1]
+            field = line.split(b"|")[-2].strip()
+            total = int(field)  # microseconds
+            return total
+
+        cmd = [sys.executable, "-c", "import pandas as pd"]
+        subprocess.run(cmd, stderr=subprocess.PIPE)

pandas/core/dtypes/dtypes.py

@@ -23,7 +23,7 @@
 ordered_sentinel = object()  # type: object
 
 
-def register_extension_dtype(cls: Type[ExtensionDtype],) -> Type[ExtensionDtype]:
+def register_extension_dtype(cls: Type[ExtensionDtype]) -> Type[ExtensionDtype]:
     """
     Register an ExtensionType with pandas as class decorator.
 

pandas/util/_test_decorators.py

@@ -102,7 +102,7 @@ def _skip_if_no_scipy():
     )
 
 
-def skip_if_installed(package: str,) -> Callable:
+def skip_if_installed(package: str) -> Callable:
     """
     Skip a test if a package is installed.