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[CASSANDRA-20753][4.0] Fix BufferPool leak in BufferPoolAllocator when a capacity needs to be extended #4262

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[CASSANDRA-20753][4.0] Fix BufferPool leak in BufferPoolAllocator when a capacity needs to be extended #4262

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7 changes: 7 additions & 0 deletions src/java/org/apache/cassandra/net/BufferPoolAllocator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,12 @@ public long usedSizeInBytes()
return bufferPool.usedSizeInBytes();
}

@VisibleForTesting
long overflowMemoryInBytes()
{
return bufferPool.overflowMemoryInBytes();
}

void release()
{
}
Expand All @@ -117,6 +123,7 @@ public ByteBuf capacity(int newCapacity)

ByteBuf newBuffer = super.capacity(newCapacity);
ByteBuffer nioBuffer = newBuffer.nioBuffer(0, newBuffer.capacity());
nioBuffer = bufferPool.unwrapBufferPoolManagedBuffer(nioBuffer);

bufferPool.put(wrapped);
wrapped = nioBuffer;
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26 changes: 26 additions & 0 deletions src/java/org/apache/cassandra/utils/memory/BufferPool.java
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Expand Up @@ -1613,4 +1613,30 @@ int unsafeNumChunks()
+ (pool.chunks.chunk1 != null ? 1 : 0)
+ (pool.chunks.chunk2 != null ? 1 : 0);
}

/**
* @return the inner buffer if it has a BufferPool.Chunk attached
* and originalBuffer in other cases
*/
public ByteBuffer unwrapBufferPoolManagedBuffer(ByteBuffer originalBuffer)
{
int MAX_DEPTH = 32; // a protection against possible loops in attachments
int depth = 0;
ByteBuffer buffer = originalBuffer;
do
{
if (buffer == null || !isExactlyDirect(buffer))
return originalBuffer;
if (Chunk.getParentChunk(buffer) != null)
return buffer;

Object attachment = MemoryUtil.getAttachment(buffer);
if (!(attachment instanceof ByteBuffer))
return originalBuffer;
Comment on lines +1629 to +1635
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in the two places where we fallback to return originalBuffer; is there any difference if originalBuffer or the previous buffer value (not the current value of buffer) was returned ?

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I relied on a common sense logic here: if we get something non-expected as an input - do not modify it and return the original value (it is also a fallback to the original behaviour), it is just a safer approach by default, IMHO

buffer = (ByteBuffer) attachment;
depth++;
}
while (depth < MAX_DEPTH);
return originalBuffer;
}
}
107 changes: 62 additions & 45 deletions test/unit/org/apache/cassandra/net/BufferPoolAllocatorTest.java
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Expand Up @@ -22,57 +22,68 @@
import java.util.Arrays;
import java.util.Random;

import org.junit.BeforeClass;
import org.junit.Test;

import io.netty.buffer.ByteBuf;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.assertj.core.api.Assertions;

import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;

public class BufferPoolAllocatorTest
{
@Test
public void testAdoptedBufferContentAfterResize() {

@BeforeClass
public static void beforeClass()
{
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(200, 500);
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
// cache size hould be more than a macro chunk size for proper pool testing
// if it is 0 or less than a macro chunk size we actually do not pool
DatabaseDescriptor.getRawConfig().networking_cache_size_in_mb = 128;
}

@Test
public void testAdoptedBufferContentAfterResize() {
ByteBuf buffer = allocateByteBuf(200, 500);
int originalCapacity = buffer.capacity();
byte[] content = new byte[300];

Random rand = new Random();
rand.nextBytes(content);

buffer.writeBytes(Arrays.copyOfRange(content, 0, 200));
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(originalCapacity, GlobalBufferPoolAllocator.instance.usedSizeInBytes());

buffer.writeBytes(Arrays.copyOfRange(content, 200, 300));
int increasedCapacity = buffer.capacity();
assertEquals(increasedCapacity, GlobalBufferPoolAllocator.instance.usedSizeInBytes());

byte[] bufferContent = new byte[300];

BufferPoolAllocator.Wrapped wrapped = (BufferPoolAllocator.Wrapped) buffer;
ByteBuffer adopted = wrapped.adopt();
adopted.get(bufferContent);
assertArrayEquals(content, bufferContent);
assertEquals(500, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(increasedCapacity, GlobalBufferPoolAllocator.instance.usedSizeInBytes());

GlobalBufferPoolAllocator.instance.put(adopted);
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

@Test
public void testAdoptedBufferContentBeforeResize() {
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(200, 300);
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ByteBuf buffer = allocateByteBuf(200, 300);
int originalCapacity = buffer.capacity();

byte[] content = new byte[200];

Random rand = new Random();
rand.nextBytes(content);

buffer.writeBytes(content);
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(originalCapacity, GlobalBufferPoolAllocator.instance.usedSizeInBytes());

byte[] bufferContent = new byte[200];

Expand All @@ -82,115 +93,121 @@ public void testAdoptedBufferContentBeforeResize() {
assertArrayEquals(content, bufferContent);

GlobalBufferPoolAllocator.instance.put(adopted);
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

@Test
public void testPutPooledBufferBackIntoPool() {
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(200, 500);
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ByteBuf buffer = allocateByteBuf(200, 500);
buffer.writeBytes(new byte[200]);

buffer.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

@Test
public void testPutResizedBufferBackIntoPool() {
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(200, 500);
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ByteBuf buffer = allocateByteBuf(200, 500);
buffer.writeBytes(new byte[500]);

buffer.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

@Test
public void testBufferDefaultMaxCapacity()
{
DatabaseDescriptor.clientInitialization();
ByteBuf noMaxCapacity = GlobalBufferPoolAllocator.instance.buffer(100);
noMaxCapacity.writeBytes(new byte[100]);
assertEquals(100, noMaxCapacity.readableBytes());
noMaxCapacity.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

@Test
public void testBufferWithMaxCapacity()
{
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(100, 500);
ByteBuf buffer = allocateByteBuf(100, 500);
buffer.writeBytes(new byte[500]);
assertEquals(500, buffer.readableBytes());
assertEquals(500, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(buffer.capacity(), GlobalBufferPoolAllocator.instance.usedSizeInBytes());
buffer.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

@Test
public void testBufferContentAfterResize()
{
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(200, 300);
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ByteBuf buffer = allocateByteBuf(200, 300);
int originalCapacity = buffer.capacity();

byte[] content = new byte[300];

Random rand = new Random();
rand.nextBytes(content);

buffer.writeBytes(Arrays.copyOfRange(content, 0, 200));
assertEquals(200, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(originalCapacity, GlobalBufferPoolAllocator.instance.usedSizeInBytes());

buffer.writeBytes(Arrays.copyOfRange(content, 200, 300));

byte[] bufferContent = new byte[300];
buffer.readBytes(bufferContent);
assertArrayEquals(content, bufferContent);
assertEquals(300, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
Assertions.assertThat(buffer.capacity()).isGreaterThanOrEqualTo(300);
assertEquals(buffer.capacity(), GlobalBufferPoolAllocator.instance.usedSizeInBytes());

buffer.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();

}

@Test(expected = IndexOutOfBoundsException.class)
public void testBufferExceedMaxCapacity()
{
DatabaseDescriptor.clientInitialization();
ByteBuf maxCapacity = GlobalBufferPoolAllocator.instance.buffer(100, 200);
ByteBuf maxCapacity = allocateByteBuf(100, 200);
try
{
maxCapacity.writeBytes(new byte[300]);
} finally {
maxCapacity.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}
}

@Test
public void testResizeBufferMultipleTimes()
{
DatabaseDescriptor.clientInitialization();
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(100, 2000);
ByteBuf buffer = allocateByteBuf(100, 2000);
buffer.writeBytes(new byte[200]);
assertEquals(200, buffer.readableBytes());
assertEquals(256, buffer.capacity());
assertEquals(256, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(buffer.capacity(), GlobalBufferPoolAllocator.instance.usedSizeInBytes());

buffer.writeBytes(new byte[100]);
assertEquals(300, buffer.readableBytes());
assertEquals(512, buffer.capacity());
assertEquals(512, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(buffer.capacity(), GlobalBufferPoolAllocator.instance.usedSizeInBytes());

buffer.writeBytes(new byte[300]);
assertEquals(600, buffer.readableBytes());
assertEquals(1024, buffer.capacity());
assertEquals(1024, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(buffer.capacity(), GlobalBufferPoolAllocator.instance.usedSizeInBytes());

buffer.release();
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
ensureThatAllMemoryIsReturnedBackToBufferPool();
}

private static ByteBuf allocateByteBuf(int initialCapacity, int maxCapacity)
{
ByteBuf buffer = GlobalBufferPoolAllocator.instance.buffer(initialCapacity, maxCapacity);
int originalCapacity = buffer.capacity();

// BufferPool can allocate more capacity than requested to avoid fragmentation
Assertions.assertThat(originalCapacity).isGreaterThanOrEqualTo(initialCapacity);
assertEquals(originalCapacity, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
return buffer;
}

private static void ensureThatAllMemoryIsReturnedBackToBufferPool()
{
assertEquals(0, GlobalBufferPoolAllocator.instance.usedSizeInBytes());
assertEquals(0, GlobalBufferPoolAllocator.instance.overflowMemoryInBytes());
}
}