[FIXED JENKINS-9845] reduce memory consumption of dependency graph...

[FIXED JENKINS-9845] reduce memory consumption of dependency graph calculation: include maven dependencies with 'unknown' version only if needed.

changelog.html

@@ -71,6 +71,9 @@ Upcoming changes</a>
   <li class=rfe>
     Run maven jobs as headless process. on OSX this avoid jumping Dock icon to take focus.
     (<a href="http://issues.jenkins-ci.org/browse/JENKINS-9785">issue 9785</a>)
+  <li class=rfe>
+    Reduce memory consumption of dependency calculation in maven jobs.
+    (<a href="http://issues.jenkins-ci.org/browse/JENKINS-9845">issue 9845</a>)
 </ul>
 </div><!--=TRUNK-END=-->
 

maven-plugin/src/main/java/hudson/maven/MavenModule.java

@@ -392,22 +392,38 @@ public final class MavenModule extends AbstractMavenProject<MavenModule,MavenBui
         if(isDisabled() || getParent().ignoreUpstremChanges())        return;
 
         MavenDependencyComputationData data = graph.getComputationalData(MavenDependencyComputationData.class);
-        
+
+        // Build a map of all Maven modules in this Jenkins instance as dependencies.
+
+        // When we load old data that doesn't record version in dependency, we'd like
+        // to emulate the old behavior that tries to identify the upstream by ignoring the version.
+        // Do this by putting groupId:artifactId:UNKNOWN to the modules list, but
+        // ONLY if we find a such an old MavenModule in this Jenkins instance.
+        boolean hasDependenciesWithUnknownVersion = hasDependenciesWithUnknownVersion();
         if (data == null) {
             Map<ModuleDependency,MavenModule> modules = new HashMap<ModuleDependency,MavenModule>();
     
-            // when we load old data that doesn't record version in dependency, we'd like
-            // to emulate the old behavior that it tries to identify the upstream by ignoring the version.
-            // do this by always putting groupId:artifactId:UNKNOWN to the modules list.
-    
             for (MavenModule m : Hudson.getInstance().getAllItems(MavenModule.class)) {
                 if(m.isDisabled())  continue;
                 ModuleDependency moduleDependency = m.asDependency();
                 modules.put(moduleDependency,m);
-                modules.put(moduleDependency.withUnknownVersion(),m);
+                if (hasDependenciesWithUnknownVersion) {
+                    modules.put(moduleDependency.withUnknownVersion(),m);
+                }
             }
             data = new MavenDependencyComputationData(modules);
+            data.withUnknownVersions = hasDependenciesWithUnknownVersion;
             graph.putComputationalData(MavenDependencyComputationData.class, data);
+        } else {
+            if (hasDependenciesWithUnknownVersion && !data.withUnknownVersions) {
+                // found 'old' MavenModule: add dependencies with unknown versions now
+                for (MavenModule m : Hudson.getInstance().getAllItems(MavenModule.class)) {
+                    if(m.isDisabled())  continue;
+                    ModuleDependency moduleDependency = m.asDependency().withUnknownVersion();
+                    data.allModules.put(moduleDependency,m);
+                }
+                data.withUnknownVersions = true;
+            }
         }
 
         // In case two modules with the same name are defined, modules in the same MavenModuleSet
@@ -424,7 +440,9 @@ public final class MavenModule extends AbstractMavenProject<MavenModule,MavenBui
                 if(m.isDisabled())  continue;
                 ModuleDependency moduleDependency = m.asDependency();
                 myParentsModules.put(moduleDependency,m);
-                myParentsModules.put(moduleDependency.withUnknownVersion(),m);
+                if (hasDependenciesWithUnknownVersion) {
+                    myParentsModules.put(moduleDependency.withUnknownVersion(),m);
+                }
             }
             
             //data.modulesPerParent.put(getParent(), myParentsModules);
@@ -449,7 +467,21 @@ public final class MavenModule extends AbstractMavenProject<MavenModule,MavenBui
         }
     }
     
+    /**
+     * Check if this module has dependencies recorded without a concrete version -
+     * which shouldn't happen for any module which was at least build once with Jenkins >= 1.207. 
+     */
+    private boolean hasDependenciesWithUnknownVersion() {
+        for (ModuleDependency dep : dependencies) {
+            if (ModuleDependency.UNKNOWN.equals(dep.version)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private static class MavenDependencyComputationData {
+        boolean withUnknownVersions = false;
         Map<ModuleDependency,MavenModule> allModules;
         
         //Map<MavenModuleSet, Map<ModuleDependency,MavenModule>> modulesPerParent = new HashMap<MavenModuleSet, Map<ModuleDependency,MavenModule>>();