Question

我有一个java类，它使用System.GC（）来计算内存使用量。但是，当我运行findbugs时，它总是报告错误的行号。问题1：我使用intellij findbugs插件以及findbugs本机GUI运行此操作。结果相同。我在这里做错了吗？

util.MemoryTestBench.lotsOfGC（）强制进行垃圾收集;除了在基准测试代码中，这是非常可疑的类：MemoryTestBench（util）行：35 - 35 ====＆gt;这是Thread.sleep（100）????????
要处理的死店类：MemoryTestBench（util）行：23 - 23 ====＆gt;返回usedMemory（） - prevUsedMemory ?????

问题2：如何抑制错误DM_GC？我尝试了@SuppressWarnings，但没有用。

测试代码如下：

package util;

import java.util.Collections;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReentrantLock;

import edu.umd.cs.findbugs.annotations.SuppressWarnings;

public class MemoryTestBench {
    @SuppressWarnings (value = "DM_GC",
                       justification = "call GC to measure memory size")
    public static long calculateMemoryUsage(ObjectFactory factory) {
        Object handle = factory.makeObject();
        long prevUsedMemory = usedMemory();
        handle = null;
        lotsOfGC();
        prevUsedMemory = usedMemory();
        handle = factory.makeObject();
        lotsOfGC();
        return usedMemory() - prevUsedMemory;
    }

    private static long usedMemory() {
        return Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();
    }


    private static void lotsOfGC() {
        for (int i = 0; i < 20; i++) {
            System.gc();
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }

    public static void showMemoryUsage(ObjectFactory factory) {
        long mem = calculateMemoryUsage(factory);
        System.out.println(
                factory.getClass().getSimpleName() + " produced " +
                        factory.makeObject().getClass().getSimpleName() +
                        " which took " + mem + " bytes");
    }

    public static void main(String[] args) {
        showMemoryUsage(new BigConcurrentHashMapFactory());
    }
}

Answer 1

您应该在 lotsOfGC 方法之前放置 @SuppressWarnings ，而不是在 calculateMemoryUsage

之前

findbugs报告错误的行号并抑制错误？

1 个答案: