Python works by using reference counting and a garbage collector of its own that reclaims back memory. It also manages its own heap memory, separately from the system heap. The heap is organized in fixed-size blocks, which are organized into pools, which are organized into arenas.
tracemalloc is a python package that allows us to programatically collect information about the memory.
tracemalloc.take_snapshot() will generate a snapshot element.
Snapshots can be compared with their compare_to() method, which includes a key_type, to group the results by filename, lineno or traceback.
Example
Fast API endpoints
import tracemalloc
tracemalloc.start(25)
FIRST_SNAPSHOT: tracemalloc.Snapshot = None
LAST_SNAPSHOT: tracemalloc.Snapshot = None
@router.get('/some/operation')
async def some_operation():
response = {...}
gc.collect()
global FIRST_SNAPSHOT
global LAST_SNAPSHOT
LAST_SNAPSHOT = tracemalloc.take_snapshot()
if FIRST_SNAPSHOT is None:
FIRST_SNAPSHOT = LAST_SNAPSHOT
return response
@router.get('/memory/snapshots', response_class=PlainTextResponse)
async def get_memory_snapshots(top: int = 10) -> str:
result = ''
global FIRST_SNAPSHOT
global LAST_SNAPSHOT
diff = LAST_SNAPSHOT.compare_to(FIRST_SNAPSHOT, 'filename')
for stat in diff[:top]:
result += f'{stat.size_diff / 1024:.2f} new KiB, '\
f'{stat.size / 1024:.2f} total KiB, '\
f'{stat.count_diff} new blocks, '\
f'{stat.count} total blocks\n''
for line in stat.traceback.format():
result += line + '\n'
result += '\n'
return resultThis will yield a result like the following when calling the GET /memory/snapshots endpoint:
0.00 new KiB, 602.31 total KiB, 0 new blocks, 6161 total blocks
File "<frozen importlib._bootstrap_external>", line 0
0.00 new KiB, 264.03 total KiB, 0 new blocks, 18 total blocks
File "/usr/local/lib/python3.8/gzip.py", line 0
0.00 new KiB, 254.15 total KiB, 0 new blocks, 25 total blocks
File "/usr/local/lib/python3.8/site-packages/uvloop/__init__.py", line 0
0.00 new KiB, 179.01 total KiB, 0 new blocks, 1777 total blocks
File "/usr/local/lib/python3.8/abc.py", line 0
0.00 new KiB, 147.27 total KiB, 0 new blocks, 1510 total blocks
File "<frozen importlib._bootstrap>", line 0
0.00 new KiB, 134.92 total KiB, 0 new blocks, 1163 total blocks
File "/usr/local/lib/python3.8/site-packages/fastapi/utils.py", line 0
0.00 new KiB, 74.03 total KiB, 0 new blocks, 959 total blocks
File "/usr/local/lib/python3.8/site-packages/uvicorn/protocols/http/httptools_impl.py", line 0
0.00 new KiB, 59.04 total KiB, 0 new blocks, 605 total blocks
File "/usr/local/lib/python3.8/site-packages/pytz/__init__.py", line 0
0.00 new KiB, 50.82 total KiB, 0 new blocks, 303 total blocks
File "/usr/local/lib/python3.8/site-packages/websockets/exceptions.py", line 0
0.00 new KiB, 48.31 total KiB, 0 new blocks, 709 total blocks
File "/usr/local/lib/python3.8/site-packages/fastapi/routing.py", line 0