[FIXED JENKINS-15747] Avoid recording too many upstream causes at any depth.

changelog.html

@@ -67,6 +67,9 @@ Upcoming changes</a>
   <li class=bug>
     Plugin icons in the sidebar were not being properly cached.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16530">issue 16530</a>)
+  <li class='major bug'>
+    Broadly as well as deeply nested build causes overwhelmed the UI after 1.482.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-15747">issue 15747</a>)
   <li class=bug>
     API typo <code>DependecyDeclarer</code> corrected.
   <li class=bug>

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

@@ -34,6 +34,7 @@ import jenkins.model.Jenkins;
 import org.kohsuke.stapler.export.Exported;
 import org.kohsuke.stapler.export.ExportedBean;
 import com.thoughtworks.xstream.converters.UnmarshallingContext;
+import java.util.concurrent.atomic.AtomicInteger;
 import javax.annotation.Nonnull;
 
 /**
@@ -106,6 +107,10 @@ public abstract class Cause {
          * Maximum depth of transitive upstream causes we want to record.
          */
         private static final int MAX_DEPTH = 10;
+        /**
+         * Maximum number of transitive upstream causes we want to record.
+         */
+        private static final int MAX_LEAF = 25;
         private String upstreamProject, upstreamUrl;
         private int upstreamBuild;
         /**
@@ -128,8 +133,9 @@ public abstract class Cause {
             upstreamProject = up.getParent().getFullName();
             upstreamUrl = up.getParent().getUrl();
             upstreamCauses = new ArrayList<Cause>();
+            AtomicInteger leaf = new AtomicInteger(MAX_LEAF);
             for (Cause c : up.getCauses()) {
-                upstreamCauses.add(trim(c, MAX_DEPTH));
+                upstreamCauses.add(trim(c, MAX_DEPTH, leaf));
             }
         }
 
@@ -140,7 +146,7 @@ public abstract class Cause {
             this.upstreamCauses = upstreamCauses;
         }
 
-        private @Nonnull Cause trim(@Nonnull Cause c, int depth) {
+        private @Nonnull Cause trim(@Nonnull Cause c, int depth, AtomicInteger leaf) {
             if (!(c instanceof UpstreamCause)) {
                 return c;
             }
@@ -148,7 +154,11 @@ public abstract class Cause {
             List<Cause> cs = new ArrayList<Cause>();
             if (depth > 0) {
                 for (Cause c2 : uc.upstreamCauses) {
-                    cs.add(trim(c2, depth - 1));
+                    if (leaf.decrementAndGet() > 0) {
+                        cs.add(trim(c2, depth - 1, leaf));
+                    } else {
+                        cs.add(new DeeplyNestedUpstreamCause());
+                    }
                 }
             } else {
                 cs.add(new DeeplyNestedUpstreamCause());

test/src/test/java/hudson/model/CauseTest.java

@@ -26,6 +26,8 @@ package hudson.model;
 
 import hudson.XmlFile;
 import java.io.File;
+import java.util.concurrent.Future;
+import java.util.regex.Pattern;
 import static org.junit.Assert.*;
 import org.junit.Rule;
 import org.junit.Test;
@@ -54,4 +56,27 @@ public class CauseTest {
         assertFalse("too big:\n" + buildXml, buildXml.contains("<upstreamBuild>1</upstreamBuild>"));
     }
 
+    @Bug(15747)
+    @Test public void broadlyNestedCauses() throws Exception {
+        FreeStyleProject a = j.createFreeStyleProject("a");
+        FreeStyleProject b = j.createFreeStyleProject("b");
+        FreeStyleProject c = j.createFreeStyleProject("c");
+        Run<?,?> last = null;
+        for (int i = 1; i <= 10; i++) {
+            Cause cause = last == null ? null : new Cause.UpstreamCause(last);
+            Future<? extends Run<?,?>> next1 = a.scheduleBuild2(0, cause);
+            a.scheduleBuild2(0, cause);
+            cause = new Cause.UpstreamCause(next1.get());
+            Future<? extends Run<?,?>> next2 = b.scheduleBuild2(0, cause);
+            b.scheduleBuild2(0, cause);
+            cause = new Cause.UpstreamCause(next2.get());
+            Future<? extends Run<?,?>> next3 = c.scheduleBuild2(0, cause);
+            c.scheduleBuild2(0, cause);
+            last = next3.get();
+        }
+        int count = new XmlFile(Run.XSTREAM, new File(last.getRootDir(), "build.xml")).asString().split(Pattern.quote("<hudson.model.Cause_-UpstreamCause")).length;
+        assertFalse("too big at " + count, count > 100);
+        //j.interactiveBreak();
+    }
+
 }