progress: avoid ui.configbool() lookup when progress bar is active
Profiling revealed that the ui.configbool('progress', 'debug') during
progress bar updates was consuming a significant amount of overhead.
This commit adds an attribute on progress bar instances that caches
this config option.
The impact on `hg perfprogress` with default options is significant:
before: ! wall 4.641942 comb 4.580000 user 4.210000 sys 0.370000 (best of 3)
after: ! wall 1.948626 comb 1.950000 user 1.950000 sys 0.000000 (best of 5)
After this change, profiling reveals that progress.progbar.progress()
is now consuming ~73% of time.
This change does not improve the execution time if the progress bar
is disabled. We may want a more comprehensive solution for that case,
as the progress bar won't be enabled in a number of scenarios (e.g.
servers and processes not attached to an interactive TTY).
I also think that overhead of ~2.0s for 1M updates is a bit high.
I suspect further refactoring of the progress bar can significantly
reduce overhead. I don't have plans to do this, however.
Differential Revision: https://phab.mercurial-scm.org/D5408
--- a/mercurial/progress.py Sun Dec 23 22:57:03 2018 -0500
+++ b/mercurial/progress.py Mon Dec 10 20:06:58 2018 +0000
@@ -104,6 +104,8 @@
self.order = self.ui.configlist('progress', 'format')
self.estimateinterval = self.ui.configwith(
float, 'progress', 'estimateinterval')
+ # developer config: progress.debug
+ self.debug = self.ui.configbool('progress', 'debug')
def show(self, now, topic, pos, item, unit, total):
if not shouldprint(self.ui):
--- a/mercurial/ui.py Sun Dec 23 22:57:03 2018 -0500
+++ b/mercurial/ui.py Mon Dec 10 20:06:58 2018 +0000
@@ -1702,6 +1702,14 @@
elif self._progbar is not None:
self._progbar.progress(topic, pos, item=item, unit=unit,
total=total)
+
+ # Looking up progress.debug in tight loops is expensive. The value
+ # is cached on the progbar object and we can avoid the lookup in
+ # the common case where a progbar is active.
+ if pos is None or not self._progbar.debug:
+ return
+
+ # Keep this logic in sync with above.
if pos is None or not self.configbool('progress', 'debug'):
return