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[FLINK-24470][streaming] Added EMA calculation for buffer size inside…
… BufferDebloater
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68 changes: 68 additions & 0 deletions
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...a/src/main/java/org/apache/flink/streaming/runtime/tasks/bufferdebloat/BufferSizeEMA.java
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| /* | ||
| * 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 | ||
| * | ||
| * https://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. | ||
| */ | ||
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| package org.apache.flink.streaming.runtime.tasks.bufferdebloat; | ||
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| import static org.apache.flink.util.Preconditions.checkArgument; | ||
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| /** Implementation of 'Exponential moving average' algorithm. */ | ||
| public class BufferSizeEMA { | ||
| private final int maxBufferSize; | ||
| private final int minBufferSize; | ||
| /** EMA algorithm specific constant which responsible for speed of reaction. */ | ||
| private final double alpha; | ||
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| private int lastBufferSize; | ||
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| public BufferSizeEMA(int maxBufferSize, int minBufferSize, long numberOfSamples) { | ||
| this.maxBufferSize = maxBufferSize; | ||
| this.minBufferSize = minBufferSize; | ||
| alpha = 2.0 / (numberOfSamples + 1); | ||
| this.lastBufferSize = maxBufferSize; | ||
| } | ||
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| /** | ||
| * Calculating the buffer size over total possible buffers size and number of buffers in use. | ||
| * | ||
| * @param totalBufferSizeInBytes Total buffers size. | ||
| * @param totalBuffers Total number of buffers in use. | ||
| * @return Throughput calculated according to implemented algorithm. | ||
| */ | ||
| public int calculateBufferSize(long totalBufferSizeInBytes, int totalBuffers) { | ||
| checkArgument(totalBufferSizeInBytes >= 0, "Size of buffer should be non negative"); | ||
| checkArgument(totalBuffers > 0, "Number of buffers should be positive"); | ||
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| // Since the result value is always limited by max buffer size while the instant value is | ||
| // potentially unlimited. It can lead to an instant change from min to max value in case | ||
| // when the instant value is significantly larger than the possible max value. | ||
| // The solution is to limit the instant buffer size by twice of current buffer size in order | ||
| // to have the same growth and shrink speeds. for example if the instant value is equal to 0 | ||
| // and the current value is 16000 we can decrease it at maximum by 1600(suppose alfa=0.1) . | ||
| // The idea is to allow increase and decrease size by the same number. So if the instant | ||
| // value would be large(for example 100000) it will be possible to increase the current | ||
| // value by 1600(the same as decreasing) because the limit will be 2 * currentValue = 32000. | ||
| // Example of change speed: | ||
| // growing = 32768, 29647, 26823, 24268, 21956, 19864 | ||
| // shrinking = 19864, 21755, 23826, 26095, 28580, 31301, 32768 | ||
| long desirableBufferSize = | ||
| Math.min(totalBufferSizeInBytes / totalBuffers, 2L * lastBufferSize); | ||
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| lastBufferSize += alpha * (desirableBufferSize - lastBufferSize); | ||
| return lastBufferSize = Math.max(minBufferSize, Math.min(lastBufferSize, maxBufferSize)); | ||
| } | ||
| } |
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91 changes: 91 additions & 0 deletions
91
...c/test/java/org/apache/flink/streaming/runtime/tasks/bufferdebloat/BufferSizeEMATest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,91 @@ | ||
| /* | ||
| * 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 | ||
| * | ||
| * https://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. | ||
| */ | ||
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| package org.apache.flink.streaming.runtime.tasks.bufferdebloat; | ||
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| import org.apache.flink.util.TestLogger; | ||
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| import org.junit.Test; | ||
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| import static org.hamcrest.MatcherAssert.assertThat; | ||
| import static org.hamcrest.Matchers.is; | ||
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| /** Test for {@link BufferSizeEMA}. */ | ||
| public class BufferSizeEMATest extends TestLogger { | ||
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| @Test | ||
| public void testCalculationBufferSize() { | ||
| BufferSizeEMA calculator = new BufferSizeEMA(200, 10, 3); | ||
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| // The result value seeks to the bottom limit but it will take a while until it reaches it. | ||
| assertThat(calculator.calculateBufferSize(111, 13), is(104)); | ||
| assertThat(calculator.calculateBufferSize(107, 7), is(59)); | ||
| assertThat(calculator.calculateBufferSize(107, 7), is(37)); | ||
| assertThat(calculator.calculateBufferSize(107, 7), is(26)); | ||
| assertThat(calculator.calculateBufferSize(107, 7), is(20)); | ||
| assertThat(calculator.calculateBufferSize(107, 7), is(17)); | ||
| assertThat(calculator.calculateBufferSize(107, 13), is(12)); | ||
| assertThat(calculator.calculateBufferSize(107, 13), is(10)); | ||
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| // Upgrade | ||
| assertThat(calculator.calculateBufferSize(333, 1), is(15)); | ||
| assertThat(calculator.calculateBufferSize(333, 1), is(22)); | ||
| assertThat(calculator.calculateBufferSize(333, 1), is(33)); | ||
| assertThat(calculator.calculateBufferSize(333, 1), is(49)); | ||
| assertThat(calculator.calculateBufferSize(333, 1), is(73)); | ||
| assertThat(calculator.calculateBufferSize(333, 1), is(109)); | ||
| } | ||
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| @Test | ||
| public void testSizeGreaterThanMaxSize() { | ||
| BufferSizeEMA calculator = new BufferSizeEMA(200, 10, 3); | ||
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| // Decrease value to less than max. | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(100)); | ||
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| // Impossible to exceed maximum. | ||
| assertThat(calculator.calculateBufferSize(1000, 1), is(150)); | ||
| assertThat(calculator.calculateBufferSize(1000, 1), is(200)); | ||
| assertThat(calculator.calculateBufferSize(1000, 1), is(200)); | ||
| } | ||
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| @Test | ||
| public void testSizeLessThanMinSize() { | ||
| BufferSizeEMA calculator = new BufferSizeEMA(200, 10, 3); | ||
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| // Impossible to less than min. | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(100)); | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(50)); | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(25)); | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(12)); | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(10)); | ||
| assertThat(calculator.calculateBufferSize(0, 1), is(10)); | ||
| } | ||
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| @Test(expected = IllegalArgumentException.class) | ||
| public void testNegativeTotalSize() { | ||
| BufferSizeEMA calculator = new BufferSizeEMA(100, 200, 2); | ||
| calculator.calculateBufferSize(-1, 1); | ||
| } | ||
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| @Test(expected = IllegalArgumentException.class) | ||
| public void testZeroBuffers() { | ||
| BufferSizeEMA calculator = new BufferSizeEMA(100, 200, 2); | ||
| calculator.calculateBufferSize(1, 0); | ||
| } | ||
| } |