Utilize buildCache in a smarter way to prevent pathological disk I/O storms.

third_party/buildbot_8_4p1/buildbot/status/web/status_json.py

 # This file is part of Buildbot.  Buildbot is free software: you can
 # redistribute it and/or modify it under the terms of the GNU General Public
 # License as published by the Free Software Foundation, version 2.
 #
 # This program is distributed in the hope that it will be useful, but WITHOUT
 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 # FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 # details.
 #
 # You should have received a copy of the GNU General Public License along with
@@ skipping 623 matching lines @@
             for builderName in self.status.getBuilderNames():
                 if self.name in self.status.getBuilder(builderName).slavenames:
                     self.builders.append(builderName)
         return self.builders
 
     def getSlaveBuildMap(self, buildcache, buildercache):
         for builderName in self.getBuilders():
             if builderName not in buildercache:
                 buildercache.add(builderName)
                 builder_status = self.status.getBuilder(builderName)
-                for i in range(1, builder_status.buildCacheSize - 1):
-                    build_status = builder_status.getBuild(-i)
+
+                buildnums = range(-1, -(builder_status.buildCacheSize - 1), -1)
+                builds = builder_status.getBuilds(buildnums)
+
+                for build_status in builds:
                     if not build_status or not build_status.isFinished():
                         # If not finished, it will appear in runningBuilds.
                         break
                     slave = buildcache[build_status.getSlavename()]
                     slave.setdefault(builderName, []).append(
                             build_status.getNumber())
         return buildcache[self.name]
 
     def asDict(self, request):
         if not hasattr(request, 'custom_data'):
@@ skipping 100 matching lines @@
         if not builder:
             return
         EXAMPLES = EXAMPLES.replace('<A_BUILDER>', builder.getName())
         build = builder.getBuild(-1)
         if build:
             EXAMPLES = EXAMPLES.replace('<A_BUILD>', str(build.getNumber()))
         if builder.slavenames:
             EXAMPLES = EXAMPLES.replace('<A_SLAVE>', builder.slavenames[0])
 
 # vim: set ts=4 sts=4 sw=4 et: