D5196: changegroup: restore default node ordering (issue6001)

lothiraldan (Boris Feld) phabricator at mercurial-scm.org
Tue Oct 30 16:28:32 UTC 2018


lothiraldan created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  Changeset https://phab.mercurial-scm.org/rHGdb5501d93bcf6ada3426a45e901094fd877e370f changed the default node ordering from "storage" to
  "linearize".
  
  While the new API is more explicit and cleaner, the "linearize" order is
  problematic on certain repositories like netbeans where it makes bundling
  slower the more nodes we bundle.
  
  Pushing and pulling 100 changesets was ~20% slower and pushing and pulling
  1000 changesets was ~600% slower.
  
  A very quick analysis of profile traces showed that the pull operation was
  taking more time creating the delta.
  
  Putting back the old default order seems to be the safe option. With more time
  during the next cycle, we can understand better the impact of sorting with the
  DAG order by default, the source of the regression and how to mitigate it.
  
  /!\ We are still waiting for the full performance impact but with this patch,
  bundling and pulling locally (not on the performance workstation) 1000
  changesets on the netbeans repository is as fast as before the regression.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D5196

AFFECTED FILES
  mercurial/utils/storageutil.py

CHANGE DETAILS

diff --git a/mercurial/utils/storageutil.py b/mercurial/utils/storageutil.py
--- a/mercurial/utils/storageutil.py
+++ b/mercurial/utils/storageutil.py
@@ -337,11 +337,11 @@
 
     if nodesorder == 'nodes':
         revs = [frev(n) for n in nodes]
-    elif nodesorder == 'storage':
-        revs = sorted(frev(n) for n in nodes)
-    else:
+    elif nodesorder == "linear":
         revs = set(frev(n) for n in nodes)
         revs = dagop.linearize(revs, store.parentrevs)
+    else: # storage and default
+        revs = sorted(frev(n) for n in nodes)
 
     prevrev = None
 



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