Re: [Monotone-devel] Absurdly long check-out duration (probable bug)

[Timothy Brownawell]

On 06/04/2010 03:40 PM, Francis Russell wrote:
> Attempting:
>
> $ mtn db init -d mtn.db
> $ mtn pull -d mtn.db monotone.ca 'net.venge.monotone.*'
>
> with monotone 0.47 under Linux, midway though the checkout CPU usage
> remained high but no more revisions came in. Seven hours later at 100%
> CPU usage, I killed the process. This looks like a bug.
>
> I tried the 0.46 Linux binary from the monotone web-site and it seemed
> to have the same issue (although I didn't run it for as long as 0.47). I
> had no issues with the 0.45 binary, which completed the checkout in
> around 20 mins.
>
> I guess something in monotone branches is giving it the issue, as
> pulling just 'net.venge.monotone' works fine for me.
>
> Can others replicate? I guess try locally if possible to avoid undue
> stress on monotone.ca.

What's happening is that at some point during the pull, a branch is 
getting a new head which is not a close relation of all the existing 
heads. So monotone walks the history graph to see if the new head is a 
descendant of the old head or not, but the search function was broken so 
that multiple paths through the same revisions aren't pruned.

This should fix it, will commit shortly.

$ mtn diff
#
# old_revision [2260b4d7a1bf77381a5dcd7fde3654b20d2f57a1]
#
# patch "database.cc"
#  from [22e4b9ab811ee3efcd5a166a67094e259ea8190a]
#    to [0bc6ce7bb27323c3724ee95f099985a3abad21f3]
#
============================================================
--- database.cc 22e4b9ab811ee3efcd5a166a67094e259ea8190a
+++ database.cc 0bc6ce7bb27323c3724ee95f099985a3abad21f3
@@ -2655,6 +2655,7 @@ database::is_a_ancestor_of_b(revision_id

   vector<revision_id> todo;
   todo.push_back(ancestor);
+  set<revision_id> seen;
   while (!todo.empty())
     {
       revision_id anc = todo.back();
@@ -2666,11 +2667,16 @@ database::is_a_ancestor_of_b(revision_id
         {
           if (*i == child)
             return true;
+          else if (seen.find(*i) != seen.end())
+            continue;
           else
             {
               get_rev_height(*i, anc_height);
               if (child_height > anc_height)
-                todo.push_back(*i);
+                {
+                  seen.insert(*i);
+                  todo.push_back(*i);
+                }
             }
         }
     }


--
Timothy

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