HBASE-27170 ByteBuffAllocator leak when decompressing blocks near min…

…SizeForReservoirUse (#4592)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
Signed-off-by: Andrew Purtell <apurtell@apache.org>
Signed-off-by: Viraj Jasani <vjasani@apache.org>

hbase-common/src/main/java/org/apache/hadoop/hbase/io/ByteBuffAllocator.java

@@ -319,11 +319,20 @@ public ByteBuff allocate(int size) {
       // just allocate the ByteBuffer from on-heap.
       bbs.add(allocateOnHeap(remain));
     }
-    ByteBuff bb = ByteBuff.wrap(bbs, () -> {
-      for (int i = 0; i < lenFromReservoir; i++) {
-        this.putbackBuffer(bbs.get(i));
-      }
-    });
+
+    ByteBuff bb;
+    // we only need a recycler if we successfully pulled from the pool
+    // this matters for determining whether to add leak detection in RefCnt
+    if (lenFromReservoir == 0) {
+      bb = ByteBuff.wrap(bbs);
+    } else {
+      bb = ByteBuff.wrap(bbs, () -> {
+        for (int i = 0; i < lenFromReservoir; i++) {
+          this.putbackBuffer(bbs.get(i));
+        }
+      });
+    }
+
     bb.limit(size);
     return bb;
   }

hbase-common/src/main/java/org/apache/hadoop/hbase/nio/ByteBuff.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.hbase.nio;
 
+import com.google.errorprone.annotations.RestrictedApi;
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
@@ -547,6 +548,28 @@ public static ByteBuff wrap(ByteBuffer buffer) {
     return wrap(buffer, RefCnt.create());
   }
 
+  /**
+   * Calling this method in strategic locations where ByteBuffs are referenced may help diagnose
+   * potential buffer leaks. We pass the buffer itself as a default hint, but one can use
+   * {@link #touch(Object)} to pass their own hint as well.
+   */
+  @Override
+  public ByteBuff touch() {
+    return touch(this);
+  }
+
+  @Override
+  public ByteBuff touch(Object hint) {
+    refCnt.touch(hint);
+    return this;
+  }
+
+  @RestrictedApi(explanation = "Should only be called in tests", link = "",
+      allowedOnPath = ".*/src/test/.*")
+  public RefCnt getRefCnt() {
+    return refCnt;
+  }
+
   /**
    * Make this private because we don't want to expose the refCnt related wrap method to upstream.
    */

hbase-common/src/main/java/org/apache/hadoop/hbase/nio/RefCnt.java

@@ -17,12 +17,16 @@
  */
 package org.apache.hadoop.hbase.nio;
 
+import com.google.errorprone.annotations.RestrictedApi;
 import org.apache.hadoop.hbase.io.ByteBuffAllocator;
 import org.apache.hadoop.hbase.io.ByteBuffAllocator.Recycler;
 import org.apache.yetus.audience.InterfaceAudience;
 
 import org.apache.hbase.thirdparty.io.netty.util.AbstractReferenceCounted;
 import org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted;
+import org.apache.hbase.thirdparty.io.netty.util.ResourceLeakDetector;
+import org.apache.hbase.thirdparty.io.netty.util.ResourceLeakDetectorFactory;
+import org.apache.hbase.thirdparty.io.netty.util.ResourceLeakTracker;
 
 /**
  * Maintain an reference count integer inside to track life cycle of {@link ByteBuff}, if the
@@ -31,7 +35,10 @@
 @InterfaceAudience.Private
 public class RefCnt extends AbstractReferenceCounted {
 
-  private Recycler recycler = ByteBuffAllocator.NONE;
+  private static final ResourceLeakDetector<RefCnt> detector =
+    ResourceLeakDetectorFactory.instance().newResourceLeakDetector(RefCnt.class);
+  private final Recycler recycler;
+  private final ResourceLeakTracker<RefCnt> leak;
 
   /**
    * Create an {@link RefCnt} with an initial reference count = 1. If the reference count become
@@ -49,15 +56,66 @@ public static RefCnt create(Recycler recycler) {
 
   public RefCnt(Recycler recycler) {
     this.recycler = recycler;
+    this.leak = recycler == ByteBuffAllocator.NONE ? null : detector.track(this);
+  }
+
+  @Override
+  public ReferenceCounted retain() {
+    maybeRecord();
+    return super.retain();
+  }
+
+  @Override
+  public ReferenceCounted retain(int increment) {
+    maybeRecord();
+    return super.retain(increment);
+  }
+
+  @Override
+  public boolean release() {
+    maybeRecord();
+    return super.release();
+  }
+
+  @Override
+  public boolean release(int decrement) {
+    maybeRecord();
+    return super.release(decrement);
   }
 
   @Override
   protected final void deallocate() {
     this.recycler.free();
+    if (leak != null) {
+      this.leak.close(this);
+    }
+  }
+
+  @Override
+  public RefCnt touch() {
+    maybeRecord();
+    return this;
   }
 
   @Override
   public final ReferenceCounted touch(Object hint) {
-    throw new UnsupportedOperationException();
+    maybeRecord(hint);
+    return this;
+  }
+
+  @RestrictedApi(explanation = "Should only be called in tests", link = "",
+      allowedOnPath = ".*/src/test/.*")
+  public Recycler getRecycler() {
+    return recycler;
+  }
+
+  private void maybeRecord() {
+    maybeRecord(null);
+  }
+
+  private void maybeRecord(Object hint) {
+    if (leak != null) {
+      leak.record(hint);
+    }
   }
 }

hbase-common/src/test/java/org/apache/hadoop/hbase/io/TestByteBuffAllocator.java

@@ -21,6 +21,7 @@
 import static org.apache.hadoop.hbase.io.ByteBuffAllocator.getHeapAllocationRatio;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
@@ -45,6 +46,21 @@ public class TestByteBuffAllocator {
   public static final HBaseClassTestRule CLASS_RULE =
     HBaseClassTestRule.forClass(TestByteBuffAllocator.class);
 
+  @Test
+  public void testRecycleOnlyPooledBuffers() {
+    int maxBuffersInPool = 10;
+    int bufSize = 1024;
+    int minSize = bufSize / 8;
+    ByteBuffAllocator alloc = new ByteBuffAllocator(true, maxBuffersInPool, bufSize, minSize);
+
+    ByteBuff buff = alloc.allocate(minSize - 1);
+    assertSame(ByteBuffAllocator.NONE, buff.getRefCnt().getRecycler());
+
+    alloc = new ByteBuffAllocator(true, 0, bufSize, minSize);
+    buff = alloc.allocate(minSize * 2);
+    assertSame(ByteBuffAllocator.NONE, buff.getRefCnt().getRecycler());
+  }
+
   @Test
   public void testAllocateByteBuffToReadInto() {
     int maxBuffersInPool = 10;
@@ -329,8 +345,6 @@ public void testByteBuffUnsupportedMethods() {
     ByteBuff buf = alloc.allocate(bufSize);
     assertException(() -> buf.retain(2));
     assertException(() -> buf.release(2));
-    assertException(() -> buf.touch());
-    assertException(() -> buf.touch(new Object()));
   }
 
   private void assertException(Runnable r) {