mercurial/utils/hashutil.py

perf: run the gc before each run

The python garbage collector is a large source of performance troubles, we run
it right before the timed section to reduce the change for the gc to add noise
to the benchmark.

import hashlib

try:
    from ..thirdparty import sha1dc  # pytype: disable=import-error

    sha1 = sha1dc.sha1
except (ImportError, AttributeError):
    sha1 = hashlib.sha1