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"""This file benchmarks GC collection time for a large number of tiny
dataclass-like instances.
For each type, the following is measured:
- Time for a single full GC pass over all the data.
- Amount of memory used to hold all the data
"""
import gc
import sys
import time
import msgspec
def sizeof(x, _seen=None):
"""Get the recursive sizeof for an object (memoized).
Not generic, works on types used in this benchmark.
"""
if _seen is None:
_seen = set()
_id = id(x)
if _id in _seen:
return 0
_seen.add(_id)
size = sys.getsizeof(x)
if isinstance(x, dict):
for k, v in x.items():
size += sizeof(k, _seen)
size += sizeof(v, _seen)
if hasattr(x, "__dict__"):
size += sizeof(x.__dict__, _seen)
if hasattr(x, "__slots__"):
for k in x.__slots__:
size += sizeof(k, _seen)
size += sizeof(getattr(x, k), _seen)
return size
class Point(msgspec.Struct):
x: int
y: int
z: int
class PointGCFalse(msgspec.Struct, gc=False):
x: int
y: int
z: int
class PointClass:
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
class PointClassSlots:
__slots__ = ("x", "y", "z")
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
def bench_gc(cls):
# Allocate a dict of structs
data = {i: cls(i, i, i) for i in range(1_000_000)}
# Run a full collection
start = time.perf_counter()
gc.collect()
stop = time.perf_counter()
gc_time = (stop - start) * 1e3
mibytes = sizeof(data) / (2**20)
return gc_time, mibytes
def format_table(results):
columns = ("", "GC time (ms)", "Memory Used (MiB)")
rows = []
for name, t, mem in results:
rows.append((f"**{name}**", f"{t:.2f}", f"{mem:.2f}"))
widths = tuple(max(max(map(len, x)), len(c)) for x, c in zip(zip(*rows), columns))
row_template = ("|" + (" %%-%ds |" * len(columns))) % widths
header = row_template % tuple(columns)
bar_underline = "+%s+" % "+".join("=" * (w + 2) for w in widths)
bar = "+%s+" % "+".join("-" * (w + 2) for w in widths)
parts = [bar, header, bar_underline]
for r in rows:
parts.append(row_template % r)
parts.append(bar)
return "\n".join(parts)
def main():
results = []
for name, cls in [
("standard class", PointClass),
("standard class with __slots__", PointClassSlots),
("msgspec struct", Point),
("msgspec struct with gc=False", PointGCFalse),
]:
print(f"Benchmarking {name}...")
gc_time, mibytes = bench_gc(cls)
results.append((name, gc_time, mibytes))
print(format_table(results))
if __name__ == "__main__":
main()
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