Close RevWalks in tests

Change-Id: Id28804ace2572e8f659271660e78454a0d6ccc49
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

7 files changed, 443 insertions, 380 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java
index 4401bcedb3..1b2c850192 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java
@@ -2136,10 +2136,12 @@ public class RebaseCommandTest extends RepositoryTestCase {
 	private List<DiffEntry> getStashedDiff() throws AmbiguousObjectException,
 			IncorrectObjectTypeException, IOException, MissingObjectException {
 		ObjectId stashId = db.resolve("stash@{0}");
-		RevWalk revWalk = new RevWalk(db);
-		RevCommit stashCommit = revWalk.parseCommit(stashId);
-		List<DiffEntry> diffs = diffWorkingAgainstHead(stashCommit, revWalk);
-		return diffs;
+		try (RevWalk revWalk = new RevWalk(db)) {
+			RevCommit stashCommit = revWalk.parseCommit(stashId);
+			List<DiffEntry> diffs = diffWorkingAgainstHead(stashCommit,
+					revWalk);
+			return diffs;
+		}
 	}
 
 	private TreeWalk createTreeWalk() {
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java
index 1e2341b6a5..6521d866b5 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackWriterTest.java
@@ -680,8 +680,9 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 	private static PackIndex writePack(FileRepository repo,
 			Set<? extends ObjectId> want, Set<ObjectIdSet> excludeObjects)
 					throws IOException {
-		RevWalk walk = new RevWalk(repo);
-		return writePack(repo, walk, 0, want, NONE, excludeObjects);
+		try (RevWalk walk = new RevWalk(repo)) {
+			return writePack(repo, walk, 0, want, NONE, excludeObjects);
+		}
 	}
 
 	private static PackIndex writeShallowPack(FileRepository repo, int depth,
@@ -689,9 +690,10 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 			Set<? extends ObjectId> shallow) throws IOException {
 		// During negotiation, UploadPack would have set up a DepthWalk and
 		// marked the client's "shallow" commits. Emulate that here.
-		DepthWalk.RevWalk walk = new DepthWalk.RevWalk(repo, depth - 1);
-		walk.assumeShallow(shallow);
-		return writePack(repo, walk, depth, want, have, EMPTY_ID_SET);
+		try (DepthWalk.RevWalk walk = new DepthWalk.RevWalk(repo, depth - 1)) {
+			walk.assumeShallow(shallow);
+			return writePack(repo, walk, depth, want, have, EMPTY_ID_SET);
+		}
 	}
 
 	private static PackIndex writePack(FileRepository repo, RevWalk walk,
@@ -707,6 +709,7 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 			if (depth > 0) {
 				pw.setShallowPack(depth, null);
 			}
+			// ow doesn't need to be closed; caller closes walk.
 			ObjectWalk ow = walk.toObjectWalkWithSameObjects();
 
 			pw.preparePack(NullProgressMonitor.INSTANCE, ow, want, have, NONE);
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftree/RefTreeDatabaseTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftree/RefTreeDatabaseTest.java
index c3f5baa67b..50e0ed27c0 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftree/RefTreeDatabaseTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftree/RefTreeDatabaseTest.java
@@ -441,8 +441,9 @@ public class RefTreeDatabaseTest {
 		ReceiveCommand cmd = command(null, B, "refs/txn/tmp");
 		BatchRefUpdate batch = refdb.newBatchUpdate();
 		batch.addCommand(cmd);
-		batch.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
-
+		try (RevWalk rw = new RevWalk(repo)) {
+			batch.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertEquals(REJECTED_OTHER_REASON, cmd.getResult());
 		assertEquals(MessageFormat.format(JGitText.get().invalidRefName,
 				"refs/txn/tmp"), cmd.getMessage());
@@ -461,8 +462,9 @@ public class RefTreeDatabaseTest {
 		ReceiveCommand cmd = command(null, B, "refs/heads/pu.lock");
 		BatchRefUpdate batch = refdb.newBatchUpdate();
 		batch.addCommand(cmd);
-		batch.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
-
+		try (RevWalk rw = new RevWalk(repo)) {
+			batch.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertEquals(REJECTED_OTHER_REASON, cmd.getResult());
 		assertEquals(JGitText.get().funnyRefname, cmd.getMessage());
 		assertEquals(txnId, getTxnCommitted());
@@ -481,7 +483,9 @@ public class RefTreeDatabaseTest {
 		ReceiveCommand cmd = command(null, B, ORIG_HEAD);
 		BatchRefUpdate batch = refdb.newBatchUpdate();
 		batch.addCommand(cmd);
-		batch.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
+		try (RevWalk rw = new RevWalk(repo)) {
+			batch.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertEquals(REJECTED_OTHER_REASON, cmd.getResult());
 		assertEquals(
 				MessageFormat.format(JGitText.get().invalidRefName, ORIG_HEAD),
@@ -500,7 +504,9 @@ public class RefTreeDatabaseTest {
 				command(B, A, "refs/heads/masters"));
 		BatchRefUpdate batchUpdate = refdb.newBatchUpdate();
 		batchUpdate.addCommand(commands);
-		batchUpdate.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
+		try (RevWalk rw = new RevWalk(repo)) {
+			batchUpdate.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertEquals(txnId, getTxnCommitted());
 
 		assertEquals(REJECTED_NONFASTFORWARD,
@@ -523,7 +529,9 @@ public class RefTreeDatabaseTest {
 		BatchRefUpdate batchUpdate = refdb.newBatchUpdate();
 		batchUpdate.setAllowNonFastForwards(true);
 		batchUpdate.addCommand(commands);
-		batchUpdate.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
+		try (RevWalk rw = new RevWalk(repo)) {
+			batchUpdate.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertNotEquals(txnId, getTxnCommitted());
 
 		Map<String, Ref> refs = refdb.getRefs(ALL);
@@ -547,13 +555,15 @@ public class RefTreeDatabaseTest {
 		BatchRefUpdate batchUpdate = refdb.newBatchUpdate();
 		batchUpdate.setAllowNonFastForwards(true);
 		batchUpdate.addCommand(commands);
-		batchUpdate.execute(new RevWalk(repo) {
+		try (RevWalk rw = new RevWalk(repo) {
 			@Override
 			public boolean isMergedInto(RevCommit base, RevCommit tip) {
 				fail("isMergedInto() should not be called");
 				return false;
 			}
-		}, NullProgressMonitor.INSTANCE);
+		}) {
+			batchUpdate.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertNotEquals(txnId, getTxnCommitted());
 
 		Map<String, Ref> refs = refdb.getRefs(ALL);
@@ -574,7 +584,9 @@ public class RefTreeDatabaseTest {
 		BatchRefUpdate batchUpdate = refdb.newBatchUpdate();
 		batchUpdate.setAllowNonFastForwards(true);
 		batchUpdate.addCommand(commands);
-		batchUpdate.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
+		try (RevWalk rw = new RevWalk(repo)) {
+			batchUpdate.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertEquals(txnId, getTxnCommitted());
 
 		assertEquals(LOCK_FAILURE, commands.get(0).getResult());
@@ -601,7 +613,9 @@ public class RefTreeDatabaseTest {
 		BatchRefUpdate batchUpdate = refdb.newBatchUpdate();
 		batchUpdate.setAllowNonFastForwards(true);
 		batchUpdate.addCommand(commands);
-		batchUpdate.execute(new RevWalk(repo), NullProgressMonitor.INSTANCE);
+		try (RevWalk rw = new RevWalk(repo)) {
+			batchUpdate.execute(rw, NullProgressMonitor.INSTANCE);
+		}
 		assertNotEquals(txnId, getTxnCommitted());
 
 		assertEquals(OK, commands.get(0).getResult());
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/AbstractPlotRendererTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/AbstractPlotRendererTest.java
index f265315338..ac157b6b87 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/AbstractPlotRendererTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/AbstractPlotRendererTest.java
@@ -44,7 +44,6 @@ package org.eclipse.jgit.revplot;
 
 import static org.junit.Assert.assertEquals;
 
-import java.io.IOException;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -55,7 +54,6 @@ import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.junit.RepositoryTestCase;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
-import org.eclipse.jgit.lib.Repository;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -83,23 +81,18 @@ public class AbstractPlotRendererTest extends RepositoryTestCase {
 		git.commit().setMessage("commit on master").call();
 		MergeResult mergeCall = merge(db.resolve("topic"));
 		ObjectId start = mergeCall.getNewHead();
-		PlotCommitList<PlotLane> commitList = createCommitList(start);
+		try (PlotWalk walk = new PlotWalk(db)) {
+			walk.markStart(walk.parseCommit(start));
+			PlotCommitList<PlotLane> commitList = new PlotCommitList<>();
+			commitList.source(walk);
+			commitList.fillTo(1000);
 
-		for (int i = 0; i < commitList.size(); i++)
-			plotRenderer.paintCommit(commitList.get(i), 30);
+			for (int i = 0; i < commitList.size(); i++)
+				plotRenderer.paintCommit(commitList.get(i), 30);
 
-		List<Integer> indentations = plotRenderer.indentations;
-		assertEquals(indentations.get(2), indentations.get(3));
-	}
-
-	private PlotCommitList<PlotLane> createCommitList(ObjectId start)
-			throws IOException {
-		TestPlotWalk walk = new TestPlotWalk(db);
-		walk.markStart(walk.parseCommit(start));
-		PlotCommitList<PlotLane> commitList = new PlotCommitList<>();
-		commitList.source(walk);
-		commitList.fillTo(1000);
-		return commitList;
+			List<Integer> indentations = plotRenderer.indentations;
+			assertEquals(indentations.get(2), indentations.get(3));
+		}
 	}
 
 	private MergeResult merge(ObjectId includeId) throws GitAPIException {
@@ -107,12 +100,6 @@ public class AbstractPlotRendererTest extends RepositoryTestCase {
 				.include(includeId).call();
 	}
 
-	private static class TestPlotWalk extends PlotWalk {
-		public TestPlotWalk(Repository repo) {
-			super(repo);
-		}
-	}
-
 	private static class TestPlotRenderer extends
 			AbstractPlotRenderer<PlotLane, Object> {
 
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/PlotCommitListTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/PlotCommitListTest.java
index 7297de3646..0c367f457e 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/PlotCommitListTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revplot/PlotCommitListTest.java
@@ -135,18 +135,19 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit b = commit(a);
 		final RevCommit c = commit(b);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(c.getId()));
-
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(c).lanePos(0).parents(b);
-		test.commit(b).lanePos(0).parents(a);
-		test.commit(a).lanePos(0).parents();
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(c.getId()));
+
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(c).lanePos(0).parents(b);
+			test.commit(b).lanePos(0).parents(a);
+			test.commit(a).lanePos(0).parents();
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -156,19 +157,20 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit c = commit(a);
 		final RevCommit d = commit(b, c);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(d.getId()));
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(d.getId()));
 
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
 
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(d).lanePos(0).parents(b, c);
-		test.commit(c).lanePos(1).parents(a);
-		test.commit(b).lanePos(0).parents(a);
-		test.commit(a).lanePos(0).parents();
-		test.noMoreCommits();
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(d).lanePos(0).parents(b, c);
+			test.commit(c).lanePos(1).parents(a);
+			test.commit(b).lanePos(0).parents(a);
+			test.commit(a).lanePos(0).parents();
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -177,20 +179,21 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit b = commit(a);
 		final RevCommit c = commit(a);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(b.getId()));
-		pw.markStart(pw.lookupCommit(c.getId()));
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(b.getId()));
+			pw.markStart(pw.lookupCommit(c.getId()));
 
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
 
-		Set<Integer> childPositions = asSet(0, 1);
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(c).lanePos(childPositions).parents(a);
-		test.commit(b).lanePos(childPositions).parents(a);
-		test.commit(a).lanePos(0).parents();
-		test.noMoreCommits();
+			Set<Integer> childPositions = asSet(0, 1);
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(c).lanePos(childPositions).parents(a);
+			test.commit(b).lanePos(childPositions).parents(a);
+			test.commit(a).lanePos(0).parents();
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -200,22 +203,23 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit c = commit(a);
 		final RevCommit d = commit(a);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(b.getId()));
-		pw.markStart(pw.lookupCommit(c.getId()));
-		pw.markStart(pw.lookupCommit(d.getId()));
-
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		Set<Integer> childPositions = asSet(0, 1, 2);
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(d).lanePos(childPositions).parents(a);
-		test.commit(c).lanePos(childPositions).parents(a);
-		test.commit(b).lanePos(childPositions).parents(a);
-		test.commit(a).lanePos(0).parents();
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(b.getId()));
+			pw.markStart(pw.lookupCommit(c.getId()));
+			pw.markStart(pw.lookupCommit(d.getId()));
+
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			Set<Integer> childPositions = asSet(0, 1, 2);
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(d).lanePos(childPositions).parents(a);
+			test.commit(c).lanePos(childPositions).parents(a);
+			test.commit(b).lanePos(childPositions).parents(a);
+			test.commit(a).lanePos(0).parents();
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -228,34 +232,35 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit f = commit(a);
 		final RevCommit g = commit(f);
 
-		PlotWalk pw = new PlotWalk(db);
-		// TODO: when we add unnecessary commit's as tips (e.g. a commit which
-		// is a parent of another tip) the walk will return those commits twice.
-		// Find out why!
-		// pw.markStart(pw.lookupCommit(a.getId()));
-		pw.markStart(pw.lookupCommit(b.getId()));
-		pw.markStart(pw.lookupCommit(c.getId()));
-		pw.markStart(pw.lookupCommit(d.getId()));
-		pw.markStart(pw.lookupCommit(e.getId()));
-		// pw.markStart(pw.lookupCommit(f.getId()));
-		pw.markStart(pw.lookupCommit(g.getId()));
-
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		Set<Integer> childPositions = asSet(0, 1, 2, 3, 4);
-		CommitListAssert test = new CommitListAssert(pcl);
-		int posG = test.commit(g).lanePos(childPositions).parents(f)
-				.getLanePos();
-		test.commit(f).lanePos(posG).parents(a);
-
-		test.commit(e).lanePos(childPositions).parents(a);
-		test.commit(d).lanePos(childPositions).parents(a);
-		test.commit(c).lanePos(childPositions).parents(a);
-		test.commit(b).lanePos(childPositions).parents(a);
-		test.commit(a).lanePos(0).parents();
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			// TODO: when we add unnecessary commit's as tips (e.g. a commit
+			// which is a parent of another tip) the walk will return those
+			// commits twice. Find out why!
+			// pw.markStart(pw.lookupCommit(a.getId()));
+			pw.markStart(pw.lookupCommit(b.getId()));
+			pw.markStart(pw.lookupCommit(c.getId()));
+			pw.markStart(pw.lookupCommit(d.getId()));
+			pw.markStart(pw.lookupCommit(e.getId()));
+			// pw.markStart(pw.lookupCommit(f.getId()));
+			pw.markStart(pw.lookupCommit(g.getId()));
+
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			Set<Integer> childPositions = asSet(0, 1, 2, 3, 4);
+			CommitListAssert test = new CommitListAssert(pcl);
+			int posG = test.commit(g).lanePos(childPositions).parents(f)
+					.getLanePos();
+			test.commit(f).lanePos(posG).parents(a);
+
+			test.commit(e).lanePos(childPositions).parents(a);
+			test.commit(d).lanePos(childPositions).parents(a);
+			test.commit(c).lanePos(childPositions).parents(a);
+			test.commit(b).lanePos(childPositions).parents(a);
+			test.commit(a).lanePos(0).parents();
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -270,25 +275,26 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit h = commit(f);
 		final RevCommit i = commit(h);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(i.getId()));
-		pw.markStart(pw.lookupCommit(g.getId()));
-
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-		Set<Integer> childPositions = asSet(0, 1);
-		CommitListAssert test = new CommitListAssert(pcl);
-		int posI = test.commit(i).lanePos(childPositions).parents(h)
-				.getLanePos();
-		test.commit(h).lanePos(posI).parents(f);
-		test.commit(g).lanePos(childPositions).parents(a);
-		test.commit(f).lanePos(posI).parents(e, d);
-		test.commit(e).lanePos(posI).parents(c);
-		test.commit(d).lanePos(2).parents(b);
-		test.commit(c).lanePos(posI).parents(b);
-		test.commit(b).lanePos(posI).parents(a);
-		test.commit(a).lanePos(0).parents();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(i.getId()));
+			pw.markStart(pw.lookupCommit(g.getId()));
+
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+			Set<Integer> childPositions = asSet(0, 1);
+			CommitListAssert test = new CommitListAssert(pcl);
+			int posI = test.commit(i).lanePos(childPositions).parents(h)
+					.getLanePos();
+			test.commit(h).lanePos(posI).parents(f);
+			test.commit(g).lanePos(childPositions).parents(a);
+			test.commit(f).lanePos(posI).parents(e, d);
+			test.commit(e).lanePos(posI).parents(c);
+			test.commit(d).lanePos(2).parents(b);
+			test.commit(c).lanePos(posI).parents(b);
+			test.commit(b).lanePos(posI).parents(a);
+			test.commit(a).lanePos(0).parents();
+		}
 	}
 
 	// test the history of the egit project between 9fdaf3c1 and e76ad9170f
@@ -330,67 +336,71 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit merge_fixed_logged_npe = commit(sort_roots,
 				fix_logged_npe);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(merge_fixed_logged_npe.getId()));
-
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		CommitListAssert test = new CommitListAssert(pcl);
-
-		// Note: all positions of side branches are rather arbitrary, but some
-		// may not overlap. Testing for the positions yielded by the current
-		// implementation, which was manually checked to not overlap.
-		final int mainPos = 0;
-		test.commit(merge_fixed_logged_npe).parents(sort_roots, fix_logged_npe)
-				.lanePos(mainPos);
-		test.commit(fix_logged_npe).parents(merge_changeset_implementation)
-				.lanePos(1);
-		test.commit(sort_roots).parents(merge_update_eclipse).lanePos(mainPos);
-		test.commit(merge_update_eclipse).parents(add_a_clear, update_eclipse)
-				.lanePos(mainPos);
-		test.commit(add_a_clear).parents(fix_broken).lanePos(mainPos);
-		test.commit(fix_broken).parents(merge_disable_comment).lanePos(mainPos);
-		test.commit(merge_disable_comment)
-				.parents(merge_resolve_handler, disable_comment)
-				.lanePos(mainPos);
-		test.commit(disable_comment).parents(clone_operation).lanePos(2);
-		test.commit(merge_resolve_handler)
-				.parents(clone_operation, resolve_handler).lanePos(mainPos);
-		test.commit(update_eclipse).parents(add_Maven).lanePos(3);
-		test.commit(clone_operation).parents(merge_changeset_implementation)
-				.lanePos(mainPos);
-		test.commit(merge_changeset_implementation)
-				.parents(merge_disable_source, changeset_implementation)
-				.lanePos(mainPos);
-		test.commit(merge_disable_source)
-				.parents(update_eclipse_iplog2, disable_source)
-				.lanePos(mainPos);
-		test.commit(update_eclipse_iplog2).parents(merge_use_remote)
-				.lanePos(mainPos);
-		test.commit(disable_source).parents(merge_use_remote).lanePos(1);
-		test.commit(merge_use_remote).parents(update_eclipse_iplog, use_remote)
-				.lanePos(mainPos);
-		test.commit(changeset_implementation).parents(clear_repositorycache)
-				.lanePos(2);
-		test.commit(update_eclipse_iplog).parents(merge_add_Maven)
-				.lanePos(mainPos);
-		test.commit(merge_add_Maven).parents(findToolBar_layout, add_Maven)
-				.lanePos(mainPos);
-		test.commit(findToolBar_layout).parents(clear_repositorycache)
-				.lanePos(mainPos);
-		test.commit(use_remote).parents(clear_repositorycache).lanePos(1);
-		test.commit(add_Maven).parents(clear_repositorycache).lanePos(3);
-		test.commit(clear_repositorycache).parents(merge_remove)
-				.lanePos(mainPos);
-		test.commit(resolve_handler).parents(merge_fix).lanePos(4);
-		test.commit(merge_remove).parents(add_simple, remove_unused)
-				.lanePos(mainPos);
-		test.commit(remove_unused).parents(merge_fix).lanePos(1);
-		test.commit(add_simple).parents(merge_fix).lanePos(mainPos);
-		test.commit(merge_fix).parents().lanePos(mainPos);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(merge_fixed_logged_npe.getId()));
+
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			CommitListAssert test = new CommitListAssert(pcl);
+
+			// Note: all positions of side branches are rather arbitrary, but
+			// some
+			// may not overlap. Testing for the positions yielded by the current
+			// implementation, which was manually checked to not overlap.
+			final int mainPos = 0;
+			test.commit(merge_fixed_logged_npe)
+					.parents(sort_roots, fix_logged_npe).lanePos(mainPos);
+			test.commit(fix_logged_npe).parents(merge_changeset_implementation)
+					.lanePos(1);
+			test.commit(sort_roots).parents(merge_update_eclipse)
+					.lanePos(mainPos);
+			test.commit(merge_update_eclipse)
+					.parents(add_a_clear, update_eclipse).lanePos(mainPos);
+			test.commit(add_a_clear).parents(fix_broken).lanePos(mainPos);
+			test.commit(fix_broken).parents(merge_disable_comment)
+					.lanePos(mainPos);
+			test.commit(merge_disable_comment)
+					.parents(merge_resolve_handler, disable_comment)
+					.lanePos(mainPos);
+			test.commit(disable_comment).parents(clone_operation).lanePos(2);
+			test.commit(merge_resolve_handler)
+					.parents(clone_operation, resolve_handler).lanePos(mainPos);
+			test.commit(update_eclipse).parents(add_Maven).lanePos(3);
+			test.commit(clone_operation).parents(merge_changeset_implementation)
+					.lanePos(mainPos);
+			test.commit(merge_changeset_implementation)
+					.parents(merge_disable_source, changeset_implementation)
+					.lanePos(mainPos);
+			test.commit(merge_disable_source)
+					.parents(update_eclipse_iplog2, disable_source)
+					.lanePos(mainPos);
+			test.commit(update_eclipse_iplog2).parents(merge_use_remote)
+					.lanePos(mainPos);
+			test.commit(disable_source).parents(merge_use_remote).lanePos(1);
+			test.commit(merge_use_remote)
+					.parents(update_eclipse_iplog, use_remote).lanePos(mainPos);
+			test.commit(changeset_implementation).parents(clear_repositorycache)
+					.lanePos(2);
+			test.commit(update_eclipse_iplog).parents(merge_add_Maven)
+					.lanePos(mainPos);
+			test.commit(merge_add_Maven).parents(findToolBar_layout, add_Maven)
+					.lanePos(mainPos);
+			test.commit(findToolBar_layout).parents(clear_repositorycache)
+					.lanePos(mainPos);
+			test.commit(use_remote).parents(clear_repositorycache).lanePos(1);
+			test.commit(add_Maven).parents(clear_repositorycache).lanePos(3);
+			test.commit(clear_repositorycache).parents(merge_remove)
+					.lanePos(mainPos);
+			test.commit(resolve_handler).parents(merge_fix).lanePos(4);
+			test.commit(merge_remove).parents(add_simple, remove_unused)
+					.lanePos(mainPos);
+			test.commit(remove_unused).parents(merge_fix).lanePos(1);
+			test.commit(add_simple).parents(merge_fix).lanePos(mainPos);
+			test.commit(merge_fix).parents().lanePos(mainPos);
+			test.noMoreCommits();
+		}
 	}
 
 	// test a history where a merge commit has two time the same parent
@@ -403,20 +413,21 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit s1 = commit(m2);
 		final RevCommit s2 = commit(s1);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(m3));
-		pw.markStart(pw.lookupCommit(s2));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(s2).nrOfPassingLanes(0);
-		test.commit(s1).nrOfPassingLanes(0);
-		test.commit(m3).nrOfPassingLanes(1);
-		test.commit(m2).nrOfPassingLanes(0);
-		test.commit(m1).nrOfPassingLanes(0);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(m3));
+			pw.markStart(pw.lookupCommit(s2));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(s2).nrOfPassingLanes(0);
+			test.commit(s1).nrOfPassingLanes(0);
+			test.commit(m3).nrOfPassingLanes(1);
+			test.commit(m2).nrOfPassingLanes(0);
+			test.commit(m1).nrOfPassingLanes(0);
+			test.noMoreCommits();
+		}
 	}
 
 	/**
@@ -465,30 +476,31 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit a4 = commit(a3);
 		final RevCommit a5 = commit(a3, a4);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(b3.getId()));
-		pw.markStart(pw.lookupCommit(c.getId()));
-		pw.markStart(pw.lookupCommit(e.getId()));
-		pw.markStart(pw.lookupCommit(a5.getId()));
-
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		// test that the commits b1, b2 and b3 are on the same position
-		int bPos = pcl.get(9).lane.position; // b1
-		assertEquals("b2 is an a different position", bPos,
-				pcl.get(7).lane.position);
-		assertEquals("b3 is on a different position", bPos,
-				pcl.get(4).lane.position);
-
-		// test that nothing blocks the connections between b1, b2 and b3
-		assertNotEquals("b lane is blocked by c", bPos,
-				pcl.get(8).lane.position);
-		assertNotEquals("b lane is blocked by a2", bPos,
-				pcl.get(6).lane.position);
-		assertNotEquals("b lane is blocked by d", bPos,
-				pcl.get(5).lane.position);
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(b3.getId()));
+			pw.markStart(pw.lookupCommit(c.getId()));
+			pw.markStart(pw.lookupCommit(e.getId()));
+			pw.markStart(pw.lookupCommit(a5.getId()));
+
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			// test that the commits b1, b2 and b3 are on the same position
+			int bPos = pcl.get(9).lane.position; // b1
+			assertEquals("b2 is an a different position", bPos,
+					pcl.get(7).lane.position);
+			assertEquals("b3 is on a different position", bPos,
+					pcl.get(4).lane.position);
+
+			// test that nothing blocks the connections between b1, b2 and b3
+			assertNotEquals("b lane is blocked by c", bPos,
+					pcl.get(8).lane.position);
+			assertNotEquals("b lane is blocked by a2", bPos,
+					pcl.get(6).lane.position);
+			assertNotEquals("b lane is blocked by d", bPos,
+					pcl.get(5).lane.position);
+		}
 	}
 
 	/**
@@ -517,23 +529,24 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit a4 = commit(a3, b2);
 		final RevCommit b3 = commit(b2);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(a4));
-		pw.markStart(pw.lookupCommit(b3));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		Set<Integer> positions = asSet(0, 1);
-		CommitListAssert test = new CommitListAssert(pcl);
-		int posB = test.commit(b3).lanePos(positions).getLanePos();
-		int posA = test.commit(a4).lanePos(positions).getLanePos();
-		test.commit(b2).lanePos(posB);
-		test.commit(a3).lanePos(posA);
-		test.commit(a2).lanePos(posA);
-		test.commit(b1).lanePos(posB);
-		test.commit(a1).lanePos(posA);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(a4));
+			pw.markStart(pw.lookupCommit(b3));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			Set<Integer> positions = asSet(0, 1);
+			CommitListAssert test = new CommitListAssert(pcl);
+			int posB = test.commit(b3).lanePos(positions).getLanePos();
+			int posA = test.commit(a4).lanePos(positions).getLanePos();
+			test.commit(b2).lanePos(posB);
+			test.commit(a3).lanePos(posA);
+			test.commit(a2).lanePos(posA);
+			test.commit(b1).lanePos(posB);
+			test.commit(a1).lanePos(posA);
+			test.noMoreCommits();
+		}
 	}
 
 	/**
@@ -562,25 +575,26 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit b3 = commit(b2);
 		final RevCommit a4 = commit(a3);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(a4));
-		pw.markStart(pw.lookupCommit(b3));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		Set<Integer> positions = asSet(0, 1);
-		CommitListAssert test = new CommitListAssert(pcl);
-		int posA = test.commit(a4).lanePos(positions).getLanePos();
-		int posB = test.commit(b3).lanePos(positions).getLanePos();
-		test.commit(a3).lanePos(posA);
-		test.commit(b2).lanePos(posB);
-		test.commit(a2).lanePos(posA);
-		// b1 is not repositioned, uses "detour lane"
-		// (drawn as a double arc in the ascii graph above)
-		test.commit(b1).lanePos(posB);
-		test.commit(a1).lanePos(posA);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(a4));
+			pw.markStart(pw.lookupCommit(b3));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			Set<Integer> positions = asSet(0, 1);
+			CommitListAssert test = new CommitListAssert(pcl);
+			int posA = test.commit(a4).lanePos(positions).getLanePos();
+			int posB = test.commit(b3).lanePos(positions).getLanePos();
+			test.commit(a3).lanePos(posA);
+			test.commit(b2).lanePos(posB);
+			test.commit(a2).lanePos(posA);
+			// b1 is not repositioned, uses "detour lane"
+			// (drawn as a double arc in the ascii graph above)
+			test.commit(b1).lanePos(posB);
+			test.commit(a1).lanePos(posA);
+			test.noMoreCommits();
+		}
 	}
 
 	/**
@@ -611,24 +625,25 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit a4 = commit(a3, b1);
 		final RevCommit b2 = commit(b1);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(a4));
-		pw.markStart(pw.lookupCommit(b2));
-		pw.markStart(pw.lookupCommit(c));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		Set<Integer> positions = asSet(0, 1, 2);
-		CommitListAssert test = new CommitListAssert(pcl);
-		int posB = test.commit(b2).lanePos(positions).getLanePos();
-		int posA = test.commit(a4).lanePos(positions).getLanePos();
-		test.commit(a3).lanePos(posA);
-		test.commit(c).lanePos(positions);
-		test.commit(a2).lanePos(posA);
-		test.commit(b1).lanePos(posB); // repositioned to go around c
-		test.commit(a1).lanePos(posA);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(a4));
+			pw.markStart(pw.lookupCommit(b2));
+			pw.markStart(pw.lookupCommit(c));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			Set<Integer> positions = asSet(0, 1, 2);
+			CommitListAssert test = new CommitListAssert(pcl);
+			int posB = test.commit(b2).lanePos(positions).getLanePos();
+			int posA = test.commit(a4).lanePos(positions).getLanePos();
+			test.commit(a3).lanePos(posA);
+			test.commit(c).lanePos(positions);
+			test.commit(a2).lanePos(posA);
+			test.commit(b1).lanePos(posB); // repositioned to go around c
+			test.commit(a1).lanePos(posA);
+			test.noMoreCommits();
+		}
 	}
 
 	/**
@@ -651,22 +666,24 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit a3 = commit(a2);
 		final RevCommit b1 = commit(a1);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(a3));
-		pw.markStart(pw.lookupCommit(b1));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(2); // don't process a1
-
-		Set<Integer> positions = asSet(0, 1);
-		CommitListAssert test = new CommitListAssert(pcl);
-		PlotLane laneB = test.commit(b1).lanePos(positions).current.getLane();
-		int posA = test.commit(a3).lanePos(positions).getLanePos();
-		test.commit(a2).lanePos(posA);
-		assertArrayEquals(
-				"Although the parent of b1, a1, is not processed yet, the b lane should still be drawn",
-				new PlotLane[] { laneB }, test.current.passingLanes);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(a3));
+			pw.markStart(pw.lookupCommit(b1));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(2); // don't process a1
+
+			Set<Integer> positions = asSet(0, 1);
+			CommitListAssert test = new CommitListAssert(pcl);
+			PlotLane laneB = test.commit(b1).lanePos(positions).current
+					.getLane();
+			int posA = test.commit(a3).lanePos(positions).getLanePos();
+			test.commit(a2).lanePos(posA);
+			assertArrayEquals(
+					"Although the parent of b1, a1, is not processed yet, the b lane should still be drawn",
+					new PlotLane[] { laneB }, test.current.passingLanes);
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -674,17 +691,18 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit a = commit();
 		final RevCommit b = commit();
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(a));
-		pw.markStart(pw.lookupCommit(b));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(b).lanePos(0);
-		test.commit(a).lanePos(0);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(a));
+			pw.markStart(pw.lookupCommit(b));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(b).lanePos(0);
+			test.commit(a).lanePos(0);
+			test.noMoreCommits();
+		}
 	}
 
 	@Test
@@ -693,17 +711,18 @@ public class PlotCommitListTest extends RevWalkTestCase {
 		final RevCommit b1 = commit();
 		final RevCommit b2 = commit(b1);
 
-		PlotWalk pw = new PlotWalk(db);
-		pw.markStart(pw.lookupCommit(a));
-		pw.markStart(pw.lookupCommit(b2));
-		PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
-		pcl.source(pw);
-		pcl.fillTo(Integer.MAX_VALUE);
-
-		CommitListAssert test = new CommitListAssert(pcl);
-		test.commit(b2).lanePos(0);
-		test.commit(b1).lanePos(0);
-		test.commit(a).lanePos(0);
-		test.noMoreCommits();
+		try (PlotWalk pw = new PlotWalk(db)) {
+			pw.markStart(pw.lookupCommit(a));
+			pw.markStart(pw.lookupCommit(b2));
+			PlotCommitList<PlotLane> pcl = new PlotCommitList<>();
+			pcl.source(pw);
+			pcl.fillTo(Integer.MAX_VALUE);
+
+			CommitListAssert test = new CommitListAssert(pcl);
+			test.commit(b2).lanePos(0);
+			test.commit(b1).lanePos(0);
+			test.commit(a).lanePos(0);
+			test.noMoreCommits();
+		}
 	}
 }
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevCommitParseTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevCommitParseTest.java
index b814984935..d6b63ab236 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevCommitParseTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevCommitParseTest.java
@@ -107,18 +107,18 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		body.append("\n");
 
-		final RevWalk rw = new RevWalk(db);
 		final RevCommit c;
 
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
 		assertNull(c.getTree());
 		assertNull(c.parents);
 
-		c.parseCanonical(rw, body.toString().getBytes(UTF_8));
-		assertNotNull(c.getTree());
-		assertEquals(treeId, c.getTree().getId());
-		assertSame(rw.lookupTree(treeId), c.getTree());
-
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, body.toString().getBytes(UTF_8));
+			assertNotNull(c.getTree());
+			assertEquals(treeId, c.getTree().getId());
+			assertSame(rw.lookupTree(treeId), c.getTree());
+		}
 		assertNotNull(c.parents);
 		assertEquals(0, c.parents.length);
 		assertEquals("", c.getFullMessage());
@@ -148,8 +148,10 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toString().getBytes(UTF_8));
-		return c;
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toString().getBytes(UTF_8));
+			return c;
+		}
 	}
 
 	@Test
@@ -161,8 +163,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toString().getBytes(UTF_8));
-
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toString().getBytes(UTF_8));
+		}
 		assertEquals("", c.getFullMessage());
 		assertEquals("", c.getShortMessage());
 	}
@@ -176,8 +179,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toString().getBytes(UTF_8));
-
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toString().getBytes(UTF_8));
+		}
 		assertEquals(new PersonIdent("", "a_u_thor@example.com", 1218123387000l, 7), c.getAuthorIdent());
 		assertEquals(new PersonIdent("", "", 1218123390000l, -5), c.getCommitterIdent());
 	}
@@ -194,8 +198,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 		b.write("\u304d\u308c\u3044\n".getBytes(UTF_8));
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67")); // bogus id
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
-
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 		assertSame(UTF_8, c.getEncoding());
 		assertEquals("F\u00f6r fattare", c.getAuthorIdent().getName());
 		assertEquals("Sm\u00f6rg\u00e5sbord", c.getShortMessage());
@@ -214,8 +219,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 		b.write("\u304d\u308c\u3044\n".getBytes(UTF_8));
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67")); // bogus id
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
-
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 		assertSame(UTF_8, c.getEncoding());
 		assertEquals("F\u00f6r fattare", c.getAuthorIdent().getName());
 		assertEquals("Sm\u00f6rg\u00e5sbord", c.getShortMessage());
@@ -240,7 +246,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 		b.write("Hi\n".getBytes("EUC-JP"));
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67")); // bogus id
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("EUC-JP", c.getEncoding().name());
 		assertEquals("F\u00f6r fattare", c.getAuthorIdent().getName());
@@ -270,7 +278,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 		b.write("Hi\n".getBytes(UTF_8));
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67")); // bogus id
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("EUC-JP", c.getEncoding().name());
 		assertEquals("F\u00f6r fattare", c.getAuthorIdent().getName());
@@ -301,7 +311,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 		b.write("Hi\n".getBytes(UTF_8));
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67")); // bogus id
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("ISO-8859-1", c.getEncoding().name());
 		assertEquals("F\u00f6r fattare", c.getAuthorIdent().getName());
@@ -323,7 +335,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		RevCommit c = new RevCommit(
 				id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 		assertEquals("'utf8'", c.getEncodingName());
 		assertEquals("Sm\u00f6rg\u00e5sbord\n", c.getFullMessage());
 
@@ -347,7 +361,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		RevCommit c = new RevCommit(
 				id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 		assertEquals("utf-8logoutputencoding=gbk", c.getEncodingName());
 		assertEquals("message\n", c.getFullMessage());
 		assertEquals("message", c.getShortMessage());
@@ -374,7 +390,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		RevCommit c = new RevCommit(
 				id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 		assertEquals("it_IT.UTF8", c.getEncodingName());
 		assertEquals("message\n", c.getFullMessage());
 		assertEquals("message", c.getShortMessage());
@@ -507,7 +525,9 @@ public class RevCommitParseTest extends RepositoryTestCase {
 
 		final RevCommit c;
 		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), commit.getBytes(UTF_8));
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, commit.getBytes(UTF_8));
+		}
 		String gpgSig = new String(c.getRawGpgSignature(), UTF_8);
 		assertTrue(gpgSig.startsWith("-----BEGIN"));
 		assertTrue(gpgSig.endsWith("END PGP SIGNATURE-----"));
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevTagParseTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevTagParseTest.java
index 1b45473066..bbc559b2db 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevTagParseTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevTagParseTest.java
@@ -91,17 +91,18 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.append("tagger A U. Thor <a_u_thor@example.com> 1218123387 +0700\n");
 		b.append("\n");
 
-		final RevWalk rw = new RevWalk(db);
 		final RevTag c;
 
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
 		assertNull(c.getObject());
 		assertNull(c.getTagName());
 
-		c.parseCanonical(rw, b.toString().getBytes(UTF_8));
-		assertNotNull(c.getObject());
-		assertEquals(id, c.getObject().getId());
-		assertSame(rw.lookupAny(id, typeCode), c.getObject());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toString().getBytes(UTF_8));
+			assertNotNull(c.getObject());
+			assertEquals(id, c.getObject().getId());
+			assertSame(rw.lookupAny(id, typeCode), c.getObject());
+		}
 	}
 
 	@Test
@@ -134,18 +135,18 @@ public class RevTagParseTest extends RepositoryTestCase {
 
 		body.append("\n");
 
-		final RevWalk rw = new RevWalk(db);
 		final RevTag c;
 
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
 		assertNull(c.getObject());
 		assertNull(c.getTagName());
 
-		c.parseCanonical(rw, body.toString().getBytes(UTF_8));
-		assertNotNull(c.getObject());
-		assertEquals(treeId, c.getObject().getId());
-		assertSame(rw.lookupTree(treeId), c.getObject());
-
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, body.toString().getBytes(UTF_8));
+			assertNotNull(c.getObject());
+			assertEquals(treeId, c.getObject().getId());
+			assertSame(rw.lookupTree(treeId), c.getObject());
+		}
 		assertNotNull(c.getTagName());
 		assertEquals(name, c.getTagName());
 		assertEquals("", c.getFullMessage());
@@ -182,17 +183,18 @@ public class RevTagParseTest extends RepositoryTestCase {
 		body.append("\n");
 		body.append(message);
 
-		final RevWalk rw = new RevWalk(db);
 		final RevTag c;
 
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
 		assertNull(c.getObject());
 		assertNull(c.getTagName());
 
-		c.parseCanonical(rw, body.toString().getBytes(UTF_8));
-		assertNotNull(c.getObject());
-		assertEquals(treeId, c.getObject().getId());
-		assertSame(rw.lookupTree(treeId), c.getObject());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, body.toString().getBytes(UTF_8));
+			assertNotNull(c.getObject());
+			assertEquals(treeId, c.getObject().getId());
+			assertSame(rw.lookupTree(treeId), c.getObject());
+		}
 
 		assertNotNull(c.getTagName());
 		assertEquals(name, c.getTagName());
@@ -213,7 +215,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 
 		final RevTag c;
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toString().getBytes(UTF_8));
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toString().getBytes(UTF_8));
+		}
 		return c;
 	}
 
@@ -234,7 +238,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("\u304d\u308c\u3044\n".getBytes(UTF_8));
 		final RevTag c;
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("F\u00f6r fattare", c.getTaggerIdent().getName());
 		assertEquals("Sm\u00f6rg\u00e5sbord", c.getShortMessage());
@@ -257,7 +263,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("\u304d\u308c\u3044\n".getBytes(UTF_8));
 		final RevTag c;
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("F\u00f6r fattare", c.getTaggerIdent().getName());
 		assertEquals("Sm\u00f6rg\u00e5sbord", c.getShortMessage());
@@ -287,7 +295,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("Hi\n".getBytes("EUC-JP"));
 		final RevTag c;
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("F\u00f6r fattare", c.getTaggerIdent().getName());
 		assertEquals("\u304d\u308c\u3044", c.getShortMessage());
@@ -320,7 +330,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("Hi\n".getBytes(UTF_8));
 		final RevTag c;
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("F\u00f6r fattare", c.getTaggerIdent().getName());
 		assertEquals("\u304d\u308c\u3044", c.getShortMessage());
@@ -355,7 +367,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("Hi\n".getBytes(UTF_8));
 		final RevTag c;
 		c = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		c.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			c.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("F\u00f6r fattare", c.getTaggerIdent().getName());
 		assertEquals("\u304d\u308c\u3044", c.getShortMessage());
@@ -374,7 +388,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("message\n".getBytes(UTF_8));
 
 		RevTag t = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		t.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			t.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("t", t.getTaggerIdent().getName());
 		assertEquals("message", t.getShortMessage());
@@ -393,7 +409,9 @@ public class RevTagParseTest extends RepositoryTestCase {
 		b.write("message\n".getBytes(UTF_8));
 
 		RevTag t = new RevTag(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
-		t.parseCanonical(new RevWalk(db), b.toByteArray());
+		try (RevWalk rw = new RevWalk(db)) {
+			t.parseCanonical(rw, b.toByteArray());
+		}
 
 		assertEquals("t", t.getTaggerIdent().getName());
 		assertEquals("message", t.getShortMessage());