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我正在测试 BigMemory Go 的性能，我注意到数据丢失。

这是单元测试：

public class BigMemoryGoPerformanceTest {

    public static void main(String[] args) throws IOException {
        BigMemoryGoPerformanceTest test = new BigMemoryGoPerformanceTest();
        test.testBigMemoryGoPerformance(args[0], Long.valueOf(args[1]), Long.valueOf(args[2]));
    }

    @DataProvider(name = "bigMemoryGoPerformance")
    public Object[][] bigMemoryGoPerformance() {
        return new Object[][] {
                   { "very small", 250000, 1 }
                  ,{ "small", 1000000, 2 }
                  ,{ "large", 10000000, 2 }
                  ,{ "very large", 50000000, 4 }
        };
    }

    @Test(dataProvider="bigMemoryGoPerformance")
    public void testBigMemoryGoPerformance(String testName, long maxRegisters, long externalMemory) throws IOException {

        Configuration managerConfiguration = new Configuration();
        managerConfiguration.updateCheck(true)
            .monitoring(Configuration.Monitoring.AUTODETECT)
            .name("config")
            .cache(new CacheConfiguration()
                .name("testperformance")
                .maxBytesLocalHeap(128, MemoryUnit.MEGABYTES)
                .maxBytesLocalOffHeap(externalMemory, MemoryUnit.GIGABYTES)
                .eternal(true)
            );

        CacheManager manager = CacheManager.create(managerConfiguration);
        Cache cache = manager.getCache("testperformance");

        try {
            System.out.println("First pass: insert " + maxRegisters + " nodes.");
            long mms = System.currentTimeMillis();
            for (long i = 0; i < maxRegisters; i++) {
                ItemForTesting item = new ItemForTesting();
                item.id = i;
                item.lastWay = i;
                item.latitude = new Double(i);
                item.longitude = new Double(i);
                cache.put( new Element(i, item) );
            }
            long timeInMMS = System.currentTimeMillis() - mms;
            System.out.println(testName + " --> Inserted " + maxRegisters + " registers in " + timeInMMS + " mms. Performance: " + ((long)(maxRegisters * 1000d / timeInMMS)) + " regs per seconds writing." );


            System.out.println("Second pass: reading " + maxRegisters + " nodes.");
            mms = System.currentTimeMillis();
            for (long i = 0; i < maxRegisters; i++) {
                Element element = cache.get(i);
                ItemForTesting item = (ItemForTesting)element.getObjectValue(); // <--- Null point exception !!!!!
            }
            timeInMMS = System.currentTimeMillis() - mms;
            System.out.println(testName + " --> Read " + maxRegisters + " registers in " + timeInMMS + " mms. Performance: " + ((long)(maxRegisters * 1000d / timeInMMS)) + " regs per seconds reading." );

            System.out.println("Third pass: updating " + maxRegisters + " nodes.");
            mms = System.currentTimeMillis();
            for (long i = 0; i < maxRegisters; i++) {
                Element element = cache.get(i);
                ItemForTesting item = (ItemForTesting)element.getObjectValue();
                item.latitude = item.latitude +1;
                cache.put( new Element(i, item) );
            }
            timeInMMS = System.currentTimeMillis() - mms;
            System.out.println(testName + " --> Updated " + maxRegisters + " registers in " + timeInMMS + " mms. Performance: " + ((long)(maxRegisters * 1000d / timeInMMS)) + " regs per seconds reading." );

            System.out.println("Fourth pass: deleting " + maxRegisters + " nodes.");
            mms = System.currentTimeMillis();
            for (long i = 0; i < maxRegisters; i++) {
                Element element = cache.get(i);
                ItemForTesting item = (ItemForTesting)element.getObjectValue();
                item.latitude = item.latitude +1;
                cache.remove( new Element(i, item) );
            }
            timeInMMS = System.currentTimeMillis() - mms;
            System.out.println(testName + " --> Removed " + maxRegisters + " registers in " + timeInMMS + " mms. Performance: " + ((long)(maxRegisters * 1000d / timeInMMS)) + " regs per seconds reading." );


        } finally {
            if (manager != null) manager.shutdown();
        }

    }

}

在“非常大”中，使用 50.000.000 次迭代，在第二遍读取数据时，返回 null。所以数据丢失了！！配置设置为永恒=真。如何避免丢失数据？

有什么问题？

谢谢！

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2 回答 2

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我怀疑您需要固定元素以避免它们过期。尝试看起来像这样的配置：

<cache name="myBigMemoryGoStore"
    maxBytesLocalHeap="1M"
    eternal="true"
    maxBytesLocalOffHeap="2G">
    <persistence strategy="none"/>
    <pinning store="inCache" />
    <sizeOfPolicy maxDepth="100000" maxDepthExceededBehavior="continue"/>

http://terracotta.org/documentation/4.0/bigmemorygo/configuration/data-life

于 2013-09-04T20:55:46.853 回答
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由于堆/堆外压力，数据可能会被驱逐。如上所述，您可以使用固定来确保您永远不会丢失数据。但仅当您确定缓存大小时才应使用固定，因为固定缓存可能会增长到无限大小或导致基于您可能使用的版本的 OOME。

另一方面，为了测试 BigMemory Go 的性能，我建议使用多线程测试来获得更多的吞吐量，而不是仅仅使用大量的迭代。

干杯，里达夫

于 2013-10-01T04:48:23.253 回答