Add explicit gc and memory reporting for UI tests

Also exit E4Testable on OOM.

This is supposed to workaround and to understand OOM errors on jenkins.

See eclipse-platform#2432

bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/E4Testable.java

@@ -13,6 +13,7 @@
  *******************************************************************************/
 package org.eclipse.e4.ui.internal.workbench.swt;
 
+import java.util.Locale;
 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.OperationCanceledException;
 import org.eclipse.core.runtime.jobs.Job;
@@ -115,24 +116,61 @@ public void testingStarting() {
 	@Override
 	public void runTest(Runnable testRunnable) {
 		Assert.isNotNull(workbench);
-		display.syncExec(
-				() -> {
-					display.addListener(SWT.Dispose,
-							e -> {
-								// lambda block to allow breakpoint for debugging
-								displayCheck = new Exception("Display is disposed");
-							});
-
-					// Run actual test
-					testRunnable.run();
-
-					while (display.readAndDispatch()) {
-						// process all pending tasks
-					}
-
-					// Display should be still there
-					checkDisplay();
-				});
+		display.syncExec(new TestExecutionRunnable(testRunnable));
+	}
+
+	private final class TestExecutionRunnable implements Runnable {
+		private final Runnable testRunnable;
+
+		private TestExecutionRunnable(Runnable testRunnable) {
+			this.testRunnable = testRunnable;
+		}
+
+		@Override
+		public void run() {
+			display.addListener(SWT.Dispose,
+					e -> {
+						// lambda block to allow breakpoint for debugging
+						displayCheck = new Exception("Display is disposed");
+					});
+
+			try {
+				// Run actual test
+				testRunnable.run();
+			} catch (OutOfMemoryError e) {
+				try {
+					e.printStackTrace(System.out);
+					printMemoryUse();
+				} finally {
+					System.out.println("Calling System.exit() after OutOfMemoryError");
+					System.exit(1);
+				}
+			}
+
+			while (display.readAndDispatch()) {
+				// process all pending tasks
+			}
+
+			// Display should be still there
+			checkDisplay();
+		}
+	}
+
+	private static void printMemoryUse() {
+		System.gc();
+		System.runFinalization();
+		System.gc();
+		System.runFinalization();
+		long max = Runtime.getRuntime().maxMemory();
+		long total = Runtime.getRuntime().totalMemory();
+		long free = Runtime.getRuntime().freeMemory();
+		long used = total - free;
+		System.out.print("\n########### Memory usage reported by JVM ########");
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes max heap", max);
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes heap allocated", total);
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes free heap", free);
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes used heap", used);
+		System.out.println("\n#################################################\n");
 	}
 
 	/**

tests/org.eclipse.ui.tests.harness/src/org/eclipse/ui/tests/harness/util/UITestCase.java

@@ -21,6 +21,7 @@
 import java.io.PrintStream;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -212,6 +213,7 @@ protected void doSetUp() throws Exception {
 	public final void tearDown() throws Exception {
 		String name = runningTest != null ? runningTest : this.getName();
 		trace(TestRunLogUtil.formatTestFinishedMessage(name));
+
 		prefMemento.resetPreferences();
 		doTearDown();
 
@@ -227,8 +229,28 @@ public final void tearDown() throws Exception {
 		fWorkbench = null;
 		assertEquals("Test leaked modal shell: [" + String.join(", ", leakedModalShellTitles) + "]", 0,
 				leakedModalShellTitles.size());
+		runGcAndPrintMemoryUse(name);
 	}
 
+	public static void runGcAndPrintMemoryUse(String testName) {
+    	System.gc();
+    	System.runFinalization();
+    	System.gc();
+    	System.runFinalization();
+    	long nax = Runtime.getRuntime().maxMemory();
+    	long total = Runtime.getRuntime().totalMemory();
+		long free = Runtime.getRuntime().freeMemory();
+		long used = total - free;
+		System.out.print("\n#################################################");
+		System.out.print("\n" + testName);
+		System.out.print("\n########### Memory usage reported by JVM ########");
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes max heap", nax);
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes heap allocated", total);
+		System.out.printf(Locale.GERMAN, "%n%,16d bytes free heap", free);
+    	System.out.printf(Locale.GERMAN, "%n%,16d bytes used heap", used);
+    	System.out.println("\n#################################################\n");
+    }
+
 	/**
 	 * Tears down the fixture, for example, close a network connection.
 	 * This method is called after a test is executed.

tests/org.eclipse.ui.tests/Eclipse UI Tests/org/eclipse/ui/tests/stress/OpenCloseTest.java

@@ -41,8 +41,12 @@
 import org.eclipse.ui.intro.IIntroPart;
 import org.eclipse.ui.part.FileEditorInput;
 import org.eclipse.ui.tests.harness.util.FileUtil;
+import org.eclipse.ui.tests.harness.util.UITestCase;
+import org.junit.After;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TestName;
 
 /**
  * Test opening and closing of items.
@@ -56,6 +60,8 @@ public class OpenCloseTest {
 	private IWorkbench workbench;
 	private IWorkbenchPage page;
 
+	@Rule
+	public TestName testName = new TestName();
 
 	@Before
 	public void setup() {
@@ -76,6 +82,10 @@ public void setup() {
 		assertNotNull(page);
 	}
 
+	@After
+	public void teardown() {
+		UITestCase.runGcAndPrintMemoryUse(testName.getMethodName());
+	}
 
 	/**
 	 * Test the opening and closing of a file.