stream-clone: disable gc for `_entries_walk` duration
The number of small container created turn Python in a gc-frenzy that seriously
impact performance.
This significantly boost performance. The following number comes from a large
private repository using perf::stream-locked-section:
base-line: 35.04 seconds
prev-change: 24.51 seconds (-30%)
this-change: 20.88 seconds (-40% from baseline; -15% from previous changes)
# mock out util.makedate() to supply testable values
import os
from mercurial import pycompat
from mercurial.utils import dateutil
def mockmakedate():
filename = os.path.join(os.environ['TESTTMP'], 'testtime')
try:
with open(filename, 'rb') as timef:
time = float(timef.read()) + 1
except IOError:
time = 0.0
with open(filename, 'wb') as timef:
timef.write(pycompat.bytestr(time))
return (time, 0)
dateutil.makedate = mockmakedate