aratno commented on code in PR #4179: URL: https://github.com/apache/cassandra/pull/4179#discussion_r2116486114
########## test/unit/org/apache/cassandra/utils/memory/MemoryUtilTest.java: ########## @@ -0,0 +1,102 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.cassandra.utils.memory; + +import java.lang.management.BufferPoolMXBean; +import java.lang.management.ManagementFactory; +import java.nio.ByteBuffer; +import java.util.List; + +import org.junit.Assert; +import org.junit.Test; + +public class MemoryUtilTest +{ + + @Test + public void testClean() + { + // We assert direct pool state changes as no ByteBuffer state changes are observable as a result of cleaner + // executing. + BufferPoolMXBean directPool = getDirectBufferPool(); + + int bufferSize = 1024 * 1024; // some non-insignificant size + ByteBuffer original = ByteBuffer.allocateDirect(bufferSize); + + long memoryUsedBefore = directPool.getMemoryUsed(); + MemoryUtil.clean(original); + long memoryUsedAfter = directPool.getMemoryUsed(); + + Assert.assertEquals("Direct memory used should decrease by buffer capacity", + // Allow 5% tolerance for other activities + memoryUsedBefore - bufferSize, memoryUsedAfter, bufferSize * 0.05); + } + + @Test + public void testCleanViewDoesNotThrow() + { + // Use a large buffer to likely get mmap'd memory from the OS. This ensures that if cleaning a view incorrectly + // unmaps the original buffer's memory, subsequent access to 'original' would more reliably fail. + // For context: glibc's mmap threshold is 32MB on 64-bit systems Review Comment: Just out of curiosity, I also confirmed that a 64MiB allocation would end up mmap'd via `vmmap`, and yes it ends up in `MallocHelperZone_`. ########## test/unit/org/apache/cassandra/utils/memory/MemoryUtilTest.java: ########## @@ -0,0 +1,102 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.cassandra.utils.memory; + +import java.lang.management.BufferPoolMXBean; +import java.lang.management.ManagementFactory; +import java.nio.ByteBuffer; +import java.util.List; + +import org.junit.Assert; +import org.junit.Test; + +public class MemoryUtilTest +{ + + @Test + public void testClean() + { + // We assert direct pool state changes as no ByteBuffer state changes are observable as a result of cleaner + // executing. + BufferPoolMXBean directPool = getDirectBufferPool(); + + int bufferSize = 1024 * 1024; // some non-insignificant size + ByteBuffer original = ByteBuffer.allocateDirect(bufferSize); + + long memoryUsedBefore = directPool.getMemoryUsed(); + MemoryUtil.clean(original); + long memoryUsedAfter = directPool.getMemoryUsed(); + + Assert.assertEquals("Direct memory used should decrease by buffer capacity", + // Allow 5% tolerance for other activities + memoryUsedBefore - bufferSize, memoryUsedAfter, bufferSize * 0.05); + } + + @Test + public void testCleanViewDoesNotThrow() + { + // Use a large buffer to likely get mmap'd memory from the OS. This ensures that if cleaning a view incorrectly + // unmaps the original buffer's memory, subsequent access to 'original' would more reliably fail. + // For context: glibc's mmap threshold is 32MB on 64-bit systems + ByteBuffer original = ByteBuffer.allocateDirect(64 * 1024 * 1024); + + ByteBuffer slice = original.slice(); + MemoryUtil.clean(slice); + try + { + original.putInt(10); + } + catch (Exception exc) + { + Assert.fail("Unable to write to original buffer after cleaning (slice). " + exc.getMessage()); Review Comment: Minor nit but `Assertions.fail` lets you pass a message and a Throwable so the full stacktrace is visible. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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