1 files changed, 172 insertions, 0 deletions
diff --git a/Lib/importlib/test/benchmark.py b/Lib/importlib/test/benchmark.py
new file mode 100644
index 00000000000..b5de6c6b010
--- /dev/null
+++ b/Lib/importlib/test/benchmark.py
@@ -0,0 +1,172 @@
+"""Benchmark some basic import use-cases.
+
+The assumption is made that this benchmark is run in a fresh interpreter and
+thus has no external changes made to import-related attributes in sys.
+
+"""
+from . import util
+from .source import util as source_util
+import decimal
+import imp
+import importlib
+import os
+import py_compile
+import sys
+import timeit
+
+
+def bench(name, cleanup=lambda: None, *, seconds=1, repeat=3):
+    """Bench the given statement as many times as necessary until total
+    executions take one second."""
+    stmt = "__import__({!r})".format(name)
+    timer = timeit.Timer(stmt)
+    for x in range(repeat):
+        total_time = 0
+        count = 0
+        while total_time < seconds:
+            try:
+                total_time += timer.timeit(1)
+            finally:
+                cleanup()
+            count += 1
+        else:
+            # One execution too far
+            if total_time > seconds:
+                count -= 1
+        yield count // seconds
+
+def from_cache(seconds, repeat):
+    """sys.modules"""
+    name = '<benchmark import>'
+    module = imp.new_module(name)
+    module.__file__ = '<test>'
+    module.__package__ = ''
+    with util.uncache(name):
+        sys.modules[name] = module
+        for result in bench(name, repeat=repeat, seconds=seconds):
+            yield result
+
+
+def builtin_mod(seconds, repeat):
+    """Built-in module"""
+    name = 'errno'
+    if name in sys.modules:
+        del sys.modules[name]
+    # Relying on built-in importer being implicit.
+    for result in bench(name, lambda: sys.modules.pop(name), repeat=repeat,
+                        seconds=seconds):
+        yield result
+
+
+def source_wo_bytecode(seconds, repeat):
+    """Source w/o bytecode: simple"""
+    sys.dont_write_bytecode = True
+    try:
+        name = '__importlib_test_benchmark__'
+        # Clears out sys.modules and puts an entry at the front of sys.path.
+        with source_util.create_modules(name) as mapping:
+            assert not os.path.exists(imp.cache_from_source(mapping[name]))
+            for result in bench(name, lambda: sys.modules.pop(name), repeat=repeat,
+                                seconds=seconds):
+                yield result
+    finally:
+        sys.dont_write_bytecode = False
+
+
+def decimal_wo_bytecode(seconds, repeat):
+    """Source w/o bytecode: decimal"""
+    name = 'decimal'
+    decimal_bytecode = imp.cache_from_source(decimal.__file__)
+    if os.path.exists(decimal_bytecode):
+        os.unlink(decimal_bytecode)
+    sys.dont_write_bytecode = True
+    try:
+        for result in bench(name, lambda: sys.modules.pop(name), repeat=repeat,
+                            seconds=seconds):
+            yield result
+    finally:
+        sys.dont_write_bytecode = False
+
+
+def source_writing_bytecode(seconds, repeat):
+    """Source writing bytecode: simple"""
+    assert not sys.dont_write_bytecode
+    name = '__importlib_test_benchmark__'
+    with source_util.create_modules(name) as mapping:
+        def cleanup():
+            sys.modules.pop(name)
+            os.unlink(imp.cache_from_source(mapping[name]))
+        for result in bench(name, cleanup, repeat=repeat, seconds=seconds):
+            assert not os.path.exists(imp.cache_from_source(mapping[name]))
+            yield result
+
+
+def decimal_writing_bytecode(seconds, repeat):
+    """Source writing bytecode: decimal"""
+    assert not sys.dont_write_bytecode
+    name = 'decimal'
+    def cleanup():
+        sys.modules.pop(name)
+        os.unlink(imp.cache_from_source(decimal.__file__))
+    for result in bench(name, cleanup, repeat=repeat, seconds=seconds):
+        yield result
+
+
+def source_using_bytecode(seconds, repeat):
+    """Bytecode w/ source: simple"""
+    name = '__importlib_test_benchmark__'
+    with source_util.create_modules(name) as mapping:
+        py_compile.compile(mapping[name])
+        assert os.path.exists(imp.cache_from_source(mapping[name]))
+        for result in bench(name, lambda: sys.modules.pop(name), repeat=repeat,
+                            seconds=seconds):
+            yield result
+
+
+def decimal_using_bytecode(seconds, repeat):
+    """Bytecode w/ source: decimal"""
+    name = 'decimal'
+    py_compile.compile(decimal.__file__)
+    for result in bench(name, lambda: sys.modules.pop(name), repeat=repeat,
+                        seconds=seconds):
+        yield result
+
+
+def main(import_):
+    __builtins__.__import__ = import_
+    benchmarks = (from_cache, builtin_mod,
+                  source_using_bytecode, source_wo_bytecode,
+                  source_writing_bytecode,
+                  decimal_using_bytecode, decimal_writing_bytecode,
+                  decimal_wo_bytecode,)
+    seconds = 1
+    seconds_plural = 's' if seconds > 1 else ''
+    repeat = 3
+    header = "Measuring imports/second over {} second{}, best out of {}\n"
+    print(header.format(seconds, seconds_plural, repeat))
+    for benchmark in benchmarks:
+        print(benchmark.__doc__, "[", end=' ')
+        sys.stdout.flush()
+        results = []
+        for result in benchmark(seconds=seconds, repeat=repeat):
+            results.append(result)
+            print(result, end=' ')
+            sys.stdout.flush()
+        assert not sys.dont_write_bytecode
+        print("]", "best is", format(max(results), ',d'))
+
+
+if __name__ == '__main__':
+    import optparse
+
+    parser = optparse.OptionParser()
+    parser.add_option('-b', '--builtin', dest='builtin', action='store_true',
+                        default=False, help="use the built-in __import__")
+    options, args = parser.parse_args()
+    if args:
+        raise RuntimeError("unrecognized args: {}".format(args))
+    import_ = __import__
+    if not options.builtin:
+        import_ = importlib.__import__
+
+    main(import_)