On one project we had a problem with leaking tests, and problem was so huge that some tests was leaking even for a few GB. We tried pytest-leaks, but it was a bit overkill and didn’t worked with our python version. So we wrote a little leak detector by ourselves.
First of all we got consumed RAM with psutil:
import os
from psutil import Process
_proc = Process(os.getpid())
def get_consumed_ram():
return _proc.memory_info().rss
Then created some log of ram usage, where nodeid
is a special pytest representation of test,
like tests/test_service.py::TestRemoteService::test_connection
:
from collections import namedtuple
START = 'START'
END = 'END'
ConsumedRamLogEntry = namedtuple('ConsumedRamLogEntry', ('nodeid', 'on', 'consumed_ram'))
consumed_ram_log = []
And logged ram usage from pytest hooks, which we just put in conftest.py
:
def pytest_runtest_setup(item):
log_entry = ConsumedRamLogEntry(item.nodeid, START, get_consumed_ram())
consumed_ram_log.append(log_entry)
def pytest_runtest_teardown(item):
log_entry = ConsumedRamLogEntry(item.nodeid, END, get_consumed_ram())
consumed_ram_log.append(log_entry)
Pytest calls pytest_runtest_setup
before each test, and pytest_runtest_teardown
after.
And after all tests we print information about tests
leaked more than allowed (10MB in our case) from
pytest_terminal_summary
hook:
from itertools import groupby
LEAK_LIMIT = 10 * 1024 * 1024
def pytest_terminal_summary(terminalreporter):
grouped = groupby(consumed_ram_log, lambda entry: entry.nodeid)
for nodeid, (start_entry, end_entry) in grouped:
leaked = end_entry.consumed_ram - start_entry.consumed_ram
if leaked > LEAK_LIMIT:
terminalreporter.write('LEAKED {}MB in {}\n'.format(
leaked / 1024 / 1024, nodeid))
So after running tests we got our leaking tests, like:
LEAKED 712MB in tests/test_service.py::TestRemoteService::test_connection