使用JVisualVM分析OOM

在idea中設定vm option為：

-Xms20m -Xmx20m -XX:+HeapDumpOnOutOfMemoryError

當出現oom時生成堆dump檔案。
使用jvisualvm執行如下程式：

public class OOMTest {
    static class OOMObject {
//        int size_1M = 1024 * 1024;
//        Byte[] bytes = new Byte[size_1M];
    }

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

        Thread.sleep(1000 * 10);
        List<OOMObject> list = new ArrayList<>();
        while (true) {
           // Thread.sleep(100);
            list.add(new OOMObject());
            System.out.println(list.size());
        }
    }
}

程式執行後，idea控制檯列印出：

540209
540210
540211
540212
540213
540214
540215
540216
540217
java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid41805.hprof ...
Heap dump file created [21011140 bytes in 0.195 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOf(Arrays.java:2245)
    at java.util.Arrays.copyOf(Arrays.java:2219)
    at java.util.ArrayList.grow(ArrayList.java:242)
    at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:216)
    at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:208)
    at java.util.ArrayList.add(ArrayList.java:440)
    at com.hao.laker.study.gc.OOMTest.main(OOMTest.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)

Process finished with exit code 1

將dump檔案使用jvisualvm開啟，分析如下：

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