Hazelcast FREE_HEAP_PERCENTAGE 政策未按预期运作

Question

当达到 JVM 上配置的最小空闲堆百分比时，Hazelcast 的 FREE_HEAP_PERCENTAGE 最大大小策略不会逐出映射条目。

下面是一个说明此问题的测试用例。如果测试是运行和其他策略类型（包括 USED_HEAP_PERCENTAGE），它会按预期工作，以便在达到此最大大小时条目被逐出。但是，如果它是运行和 FREE_HEAP_PERCENTAGE，则条目永远不会从映射中逐出，尽管空闲堆百分比超出了允许的百分比（如果运行可以确认）以管理中心为例）。

public class HazelcastMaxSizeTest {

    private static final String GROUP_NAME = "TEST";
    private static final String MAP_NAME = "test";

    private static MaxSizeConfig POLICY_THAT_WORKS = new MaxSizeConfig(5, MaxSizeConfig.MaxSizePolicy.USED_HEAP_PERCENTAGE);
    private static MaxSizeConfig POLICY_THAT_DOES_NOT_WORK = new MaxSizeConfig(99, MaxSizeConfig.MaxSizePolicy.FREE_HEAP_PERCENTAGE);

    public static void main(String[] args) throws Exception {

        HazelcastInstance instance = startHazelcast("hazelcast1", POLICY_THAT_DOES_NOT_WORK);
        System.out.println("started " + instance.getName());

        IMap<Long, byte[]> map = createMap(instance, MAP_NAME);
        System.out.println("map size: " + map.size());

        instance.shutdown();
    }

    private static HazelcastInstance startHazelcast(String instanceName, MaxSizeConfig maxSizeConfig) {

        MapConfig mapConfig = new MapConfig(MAP_NAME);
        mapConfig.setMaxSizeConfig(maxSizeConfig);
        mapConfig.setStatisticsEnabled(true);
        mapConfig.setEvictionPolicy(EvictionPolicy.LRU);
        mapConfig.setMinEvictionCheckMillis(0L);
        mapConfig.setBackupCount(1);

        Config config = new Config(instanceName);
        config.addMapConfig(mapConfig);
        config.getManagementCenterConfig().setEnabled(true);
        config.getManagementCenterConfig().setUrl("http://localhost:8080/mancenter");
        config.getGroupConfig().setName(GROUP_NAME).setPassword(GROUP_NAME);
        return Hazelcast.getOrCreateHazelcastInstance(config);
    }

    private static IMap<Long, byte[]> createMap(HazelcastInstance instance, String mapname) {

        IMap<Long, byte[]> map = instance.getMap(mapname);

        map.addEntryListener(new EntryEvictedListener<Long, byte[]>() {

            @Override
            public void entryEvicted(EntryEvent<Long, byte[]> event) {
                System.out.println("evicted " + event.getName() + ": " + event.getKey());
            }

        }, false);

        for (long i = 1; i <= 50_000; i++) {
            map.set(i, new byte[100]);
            if (i % 1000 == 0) {
                System.out.println("set " + map.getName() + ": " + i);
            }
        }

        return map;
    }

}

经过进一步调试，我想知道 Hazelcast 的 EvictionChecker may be incorrectly calculating free heap percentage. While debugging, I found that the calculated free heap percentage was greater than 100. It's calculation uses available / total, but as described here 是否应该是 available / max？

我的配置或 FREE_HEAP_PERCENTAGE 策略的预期使用有问题吗？或者这是一个 Hazelcast 错误？

规格：Hazelcast 3.6，-Xmx256m

Answer 1

进一步调试后，我发现 FREE_HEAP_PERCENTAGE 策略的意外行为是由于 Hazelcast 计算可用内存时存在错误。此问题已在 Hazelcast 的问题跟踪器中报告为 Issue 7599。

Hazelcast FREE_HEAP_PERCENTAGE 政策未按预期运作

Hazelcast FREE_HEAP_PERCENTAGE policy not working as expected

java

hazelcast

hazelcast-imap