diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java
index 7bdc5bce4..e1ee1441d 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectReader.java
@@ -44,9 +44,13 @@
 package org.eclipse.jgit.lib;
 
 import java.io.IOException;
+import java.util.Collection;
 
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.revwalk.ObjectWalk;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.storage.pack.ObjectReuseAsIs;
 
 /**
@@ -173,6 +177,44 @@ public abstract class ObjectReader {
 		return open(objectId, typeHint).getSize();
 	}
 
+	/**
+	 * Advice from a {@link RevWalk} that a walk is starting from these roots.
+	 *
+	 * @param walk
+	 *            the revision pool that is using this reader.
+	 * @param roots
+	 *            starting points of the revision walk. The starting points have
+	 *            their headers parsed, but might be missing bodies.
+	 * @throws IOException
+	 *             the reader cannot initialize itself to support the walk.
+	 */
+	public void walkAdviceBeginCommits(RevWalk walk, Collection<RevCommit> roots)
+			throws IOException {
+		// Do nothing by default, most readers don't want or need advice.
+	}
+
+	/**
+	 * Advice from an {@link ObjectWalk} that trees will be traversed.
+	 *
+	 * @param ow
+	 *            the object pool that is using this reader.
+	 * @param min
+	 *            the first commit whose root tree will be read.
+	 * @param max
+	 *            the last commit whose root tree will be read.
+	 * @throws IOException
+	 *             the reader cannot initialize itself to support the walk.
+	 */
+	public void walkAdviceBeginTrees(ObjectWalk ow, RevCommit min, RevCommit max)
+			throws IOException {
+		// Do nothing by default, most readers don't want or need advice.
+	}
+
+	/** Advice from that a walk is over. */
+	public void walkAdviceEnd() {
+		// Do nothing by default, most readers don't want or need advice.
+	}
+
 	/**
 	 * Release any resources used by this reader.
 	 * <p>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/MergeBaseGenerator.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/MergeBaseGenerator.java
index 76510ce38..735f7d602 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/MergeBaseGenerator.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/MergeBaseGenerator.java
@@ -137,6 +137,7 @@ class MergeBaseGenerator extends Generator {
 		for (;;) {
 			final RevCommit c = pending.next();
 			if (c == null) {
+				walker.reader.walkAdviceEnd();
 				walker.reader.release();
 				return null;
 			}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/ObjectWalk.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/ObjectWalk.java
index a6ecfe219..3df5a468f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/ObjectWalk.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/ObjectWalk.java
@@ -91,6 +91,10 @@ public class ObjectWalk extends RevWalk {
 
 	private RevObject last;
 
+	private RevCommit firstCommit;
+
+	private RevCommit lastCommit;
+
 	/**
 	 * Create a new revision and object walker for a given repository.
 	 *
@@ -235,6 +239,9 @@ public class ObjectWalk extends RevWalk {
 				}
 				continue;
 			}
+			if (firstCommit == null)
+				firstCommit = r;
+			lastCommit = r;
 			pendingObjects.add(r.getTree());
 			return r;
 		}
@@ -295,11 +302,19 @@ public class ObjectWalk extends RevWalk {
 			treeWalk = treeWalk.next();
 		}
 
+		if (firstCommit != null) {
+			reader.walkAdviceBeginTrees(this, firstCommit, lastCommit);
+			firstCommit = null;
+			lastCommit = null;
+		}
+
 		last = null;
 		for (;;) {
 			final RevObject o = pendingObjects.next();
-			if (o == null)
+			if (o == null) {
+				reader.walkAdviceEnd();
 				return null;
+			}
 			if ((o.flags & SEEN) != 0)
 				continue;
 			o.flags |= SEEN;
@@ -403,6 +418,8 @@ public class ObjectWalk extends RevWalk {
 		treeWalk = new CanonicalTreeParser();
 		currentTree = null;
 		last = null;
+		firstCommit = null;
+		lastCommit = null;
 	}
 
 	@Override
@@ -412,6 +429,8 @@ public class ObjectWalk extends RevWalk {
 		treeWalk = new CanonicalTreeParser();
 		currentTree = null;
 		last = null;
+		firstCommit = null;
+		lastCommit = null;
 	}
 
 	private void addObject(final RevObject o) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/PendingGenerator.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/PendingGenerator.java
index 0e2bb9832..ec7069b4d 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/PendingGenerator.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/PendingGenerator.java
@@ -128,7 +128,9 @@ class PendingGenerator extends Generator {
 			for (;;) {
 				final RevCommit c = pending.next();
 				if (c == null) {
-					walker.reader.release();
+					walker.reader.walkAdviceEnd();
+					if (!(walker instanceof ObjectWalk))
+						walker.reader.release();
 					return null;
 				}
 
@@ -174,6 +176,7 @@ class PendingGenerator extends Generator {
 					c.disposeBody();
 			}
 		} catch (StopWalkException swe) {
+			walker.reader.walkAdviceEnd();
 			walker.reader.release();
 			pending.clear();
 			return null;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java
index 7406bb60c..5f8fd5c8a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java
@@ -172,7 +172,7 @@ public class RevWalk implements Iterable<RevCommit> {
 
 	int carryFlags = UNINTERESTING;
 
-	private final ArrayList<RevCommit> roots;
+	final ArrayList<RevCommit> roots;
 
 	AbstractRevQueue queue;
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/StartGenerator.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/StartGenerator.java
index 5e778a416..fbff02778 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/StartGenerator.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/StartGenerator.java
@@ -85,6 +85,8 @@ class StartGenerator extends Generator {
 		final TreeFilter tf = w.getTreeFilter();
 		AbstractRevQueue q = walker.queue;
 
+		w.reader.walkAdviceBeginCommits(w, w.roots);
+
 		if (rf == RevFilter.MERGE_BASE) {
 			// Computing for merge bases is a special case and does not
 			// use the bulk of the generator pipeline.