BAEL 4064 Out of Memory Error

core-java-modules/core-java-lang/src/test/java/com/baeldung/error/oom/TestExecutorService.java

@@ -0,0 +1,39 @@
+package com.baeldung.error.oom;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+import org.junit.jupiter.api.Test;
+
+public class TestExecutorService {
+
+    @Test
+    public void givenAnExecutorService_WhenMoreTasksSubmitted_ThenAdditionalTasksWait() {
+
+        //Given
+        int noOfThreads = 5;
+        ExecutorService executorService = Executors.newFixedThreadPool(noOfThreads);
+
+        Runnable runnableTask = () -> {
+            try {
+                TimeUnit.HOURS.sleep(1);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        };
+
+        //When
+        IntStream.rangeClosed(1, 10)
+            .forEach(i -> executorService.submit(runnableTask));
+        
+        //Then
+        assertThat(((ThreadPoolExecutor )executorService).getQueue().size(), is(equalTo(5)));
+    }
+}