[FIXED JENKINS-8408]

If slaves are late to come online after a Jenkins startup, we will see a huge spike of builds as Jenkins attempt to get a workspace for polling.

changelog.html

@@ -55,6 +55,9 @@ Upcoming changes</a>
 <!-- Record your changes in the trunk here. -->
 <div id="trunk" style="display:none"><!--=TRUNK-BEGIN=-->
 <ul class=image>
+  <li class=bug>
+    Do not polling
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-8408">issue 8408</a>)
   <li class=bug>
     Fixed the handling of nested variable expansion.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20280">issue 20280</a>)

core/src/main/java/hudson/model/AbstractProject.java

@@ -81,11 +81,13 @@ import hudson.util.AlternativeUiTextProvider;
 import hudson.util.AlternativeUiTextProvider.Message;
 import hudson.util.DescribableList;
 import hudson.util.FormValidation;
+import hudson.util.TimeUnit2;
 import hudson.widgets.BuildHistoryWidget;
 import hudson.widgets.HistoryWidget;
 import jenkins.model.Jenkins;
 import jenkins.model.JenkinsLocationConfiguration;
 import jenkins.model.ModelObjectWithChildren;
+import jenkins.model.Uptime;
 import jenkins.model.lazy.AbstractLazyLoadRunMap.Direction;
 import jenkins.scm.DefaultSCMCheckoutStrategyImpl;
 import jenkins.scm.SCMCheckoutStrategy;
@@ -1532,7 +1534,19 @@ public abstract class AbstractProject<P extends AbstractProject<P,R>,R extends A
                     }
                 }
 
-                // build now, or nothing will ever be built
+                // At this point we start thinking about triggering a build just to get a workspace,
+                // because otherwise there's no way we can detect changes.
+                // However, first there are some conditions in which we do not want to do so.
+
+                // give time for slaves to come online if we are right after reconnection (JENKINS-8408)
+                long running = Jenkins.getInstance().getInjector().getInstance(Uptime.class).getUptime();
+                long remaining = TimeUnit2.MINUTES.toMillis(10)-running;
+                if (remaining>0) {
+                    listener.getLogger().print(Messages.AbstractProject_AwaitingWorkspaceToComeOnline(remaining/1000));
+                    listener.getLogger().println( " (" + workspaceOfflineReason.name() + ")");
+                    return NO_CHANGES;
+                }
+
                 Label label = getAssignedLabel();
                 if (label != null && label.isSelfLabel()) {
                     // if the build is fixed on a node, then attempting a build will do us
@@ -1541,17 +1555,19 @@ public abstract class AbstractProject<P extends AbstractProject<P,R>,R extends A
                     listener.getLogger().println( " (" + workspaceOfflineReason.name() + ")");
                     return NO_CHANGES;
                 }
+
                 listener.getLogger().println( ws==null
                     ? Messages.AbstractProject_WorkspaceOffline()
                     : Messages.AbstractProject_NoWorkspace());
                 if (isInQueue()) {
                     listener.getLogger().println(Messages.AbstractProject_AwaitingBuildForWorkspace());
                     return NO_CHANGES;
-                } else {
-                    listener.getLogger().print(Messages.AbstractProject_NewBuildForWorkspace());
-                    listener.getLogger().println( " (" + workspaceOfflineReason.name() + ")");
-                    return BUILD_NOW;
                 }
+
+                // build now, or nothing will ever be built
+                listener.getLogger().print(Messages.AbstractProject_NewBuildForWorkspace());
+                listener.getLogger().println( " (" + workspaceOfflineReason.name() + ")");
+                return BUILD_NOW;
             } else {
                 WorkspaceList l = b.getBuiltOn().toComputer().getWorkspaceList();
                 return pollWithWorkspace(listener, scm, b, ws, l);

core/src/main/resources/hudson/model/Messages.properties

@@ -33,6 +33,7 @@ AbstractItem.Pronoun=Job
 AbstractProject.AssignedLabelString_NoMatch_DidYouMean=There\u2019s no slave/cloud that matches this assignment. Did you mean \u2018{1}\u2019 instead of \u2018{0}\u2019?
 AbstractProject.NewBuildForWorkspace=Scheduling a new build to get a workspace.
 AbstractProject.AwaitingBuildForWorkspace=Awaiting build to get a workspace.
+AbstractProject.AwaitingWorkspaceToComeOnline=We need to schedule a new build to get a workspace, but deferring {0}ms in the hope that one will become available soon
 AbstractProject.Pronoun=Project
 AbstractProject.Aborted=Aborted
 AbstractProject.BuildInProgress=Build #{0} is already in progress{1}