570485: CI Build failures due to OutOfMemoryError or SIGKILL

Dispose of snapshots from collection tests when not
needed anymore.

Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=570485

Change-Id: I76f271352244efb9a44104e65d99eaf508c2d75e

plugins/org.eclipse.mat.tests/src/org/eclipse/mat/tests/TestSnapshots.java

@@ -109,6 +109,28 @@ public static ISnapshot getSnapshot(String name, boolean pristine)
         return getSnapshot(name, new HashMap<String, String>(), pristine);
     }
 
+    /**
+     * This snapshot can be disposed as it won't be used again.
+     * The dump file itself is not deleted, but will be tidied up
+     * at the end.
+     * @param name
+     * @return true if successfully disposed.
+     */
+    public static boolean freeSnapshot(String name)
+    {
+        ISnapshot answer = snapshots.get(name);
+        if (answer != null)
+        {
+            answer.dispose();
+            snapshots.remove(name);
+            return true;
+        }
+        else
+        {
+            return false;
+        }
+    }
+
     /**
      * Get a snapshot from a dump
      * 

plugins/org.eclipse.mat.tests/src/org/eclipse/mat/tests/collect/ExtractCollectionEntriesTest3.java

@@ -210,6 +210,8 @@ public static Collection<Object[]> data3() throws SnapshotException, IOException
                         if (objects != null)
                             parms.add(objects);
                     }
+                    Object[] objects = new Object[] { dmppath, dmpname, 7, null};
+                    parms.add(objects);
                     // To ensure it isn't garbage collected early
                     System.out.println(cdp);
                 }
@@ -251,6 +253,13 @@ public void testCollections() throws SnapshotException
                 assumeThat(type, equalTo(6));
                 testCollections6(TestSnapshots.getSnapshot(snapfile,false), classname);
                 break;
+            case 7:
+                assumeThat(type, equalTo(7));
+                if (TestSnapshots.freeSnapshot(snapfile))
+                {
+                    System.out.println("Unable to dispose of snapshot " + snapfile);
+                }
+                break;
         }
     }