BAEL-7063: OOM example (#15730)

core-java-modules/core-java-perf-2/src/test/java/com/baeldung/oom/OomCrashUnitTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.oom;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled
+class OomCrashUnitTest {
+
+    public static final Runnable MEMORY_LEAK = () -> {
+        List<byte[]> list = new ArrayList<>();
+        while (true) {
+            list.add(tenMegabytes());
+        }
+    };
+
+    @Test
+    void givenMemoryLeakCode_whenRunInsideThread_thenMainAppDoestFail() throws InterruptedException {
+        Thread memoryLeakThread = new Thread(MEMORY_LEAK);
+        memoryLeakThread.start();
+        memoryLeakThread.join();
+    }
+
+    @Test
+    void givenMemoryLeakCode_whenRunSeveralTimesInsideThread_thenMainAppDoestFail() throws InterruptedException {
+        for (int i = 0; i < 5; i++) {
+            Thread memoryLeakThread = new Thread(MEMORY_LEAK);
+            memoryLeakThread.start();
+            memoryLeakThread.join();
+        }
+    }
+
+    @Test
+    void givenBadExample_whenUseItInProductionCode_thenQuestionedByEmployerAndProbablyFired()
+      throws InterruptedException {
+        Thread npeThread = new Thread(() -> {
+            String nullString = null;
+            try {
+                nullString.isEmpty();
+            } catch (NullPointerException e) {
+                throw new OutOfMemoryError(e.getMessage());
+            }
+        });
+        npeThread.start();
+        npeThread.join();
+    }
+
+    private static byte[] tenMegabytes() {
+        return new byte[1024 * 1014 * 10];
+    }
+}