| /* |
| * 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.dubbo.common.threadpool; |
| |
| import org.apache.dubbo.common.resource.GlobalResourcesRepository; |
| import org.apache.dubbo.common.utils.NamedThreadFactory; |
| |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * {@link java.lang.Runtime#freeMemory()} technology is used to calculate the |
| * memory limit by using the percentage of the current maximum available memory, |
| * which can be used with {@link MemoryLimiter}. |
| * |
| * @see MemoryLimiter |
| * @see <a href="https://github.com/apache/incubator-shenyu/blob/master/shenyu-common/src/main/java/org/apache/shenyu/common/concurrent/MemoryLimitCalculator.java">MemoryLimitCalculator</a> |
| */ |
| public class MemoryLimitCalculator { |
| |
| private static volatile long maxAvailable; |
| |
| private static final AtomicBoolean refreshStarted = new AtomicBoolean(false); |
| |
| private static void refresh() { |
| maxAvailable = Runtime.getRuntime().freeMemory(); |
| } |
| |
| private static void checkAndScheduleRefresh() { |
| if (!refreshStarted.get()) { |
| // immediately refresh when first call to prevent maxAvailable from being 0 |
| // to ensure that being refreshed before refreshStarted being set as true |
| // notice: refresh may be called for more than once because there is no lock |
| refresh(); |
| if (refreshStarted.compareAndSet(false, true)) { |
| ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(new NamedThreadFactory("Dubbo-Memory-Calculator")); |
| // check every 50 ms to improve performance |
| scheduledExecutorService.scheduleWithFixedDelay(MemoryLimitCalculator::refresh, 50, 50, TimeUnit.MILLISECONDS); |
| GlobalResourcesRepository.registerGlobalDisposable(() -> { |
| refreshStarted.set(false); |
| scheduledExecutorService.shutdown(); |
| }); |
| } |
| } |
| } |
| |
| /** |
| * Get the maximum available memory of the current JVM. |
| * |
| * @return maximum available memory |
| */ |
| public static long maxAvailable() { |
| checkAndScheduleRefresh(); |
| return maxAvailable; |
| } |
| |
| /** |
| * Take the current JVM's maximum available memory |
| * as a percentage of the result as the limit. |
| * |
| * @param percentage percentage |
| * @return available memory |
| */ |
| public static long calculate(final float percentage) { |
| if (percentage <= 0 || percentage > 1) { |
| throw new IllegalArgumentException(); |
| } |
| checkAndScheduleRefresh(); |
| return (long) (maxAvailable() * percentage); |
| } |
| |
| /** |
| * By default, it takes 80% of the maximum available memory of the current JVM. |
| * |
| * @return available memory |
| */ |
| public static long defaultLimit() { |
| checkAndScheduleRefresh(); |
| return (long) (maxAvailable() * 0.8); |
| } |
| } |