[Fix #722] Close executor service if created

Author: fjtirado

examples/simpleGet/src/main/java/io/serverlessworkflow/impl/BlockingExample.java

@@ -30,7 +30,7 @@ public static void main(String[] args) throws IOException {
       logger.info(
           "Workflow output is {}",
           appl.workflowDefinition(WorkflowReader.readWorkflowFromClasspath("get.yaml"))
-              .instance(Map.of("petId", 10))
+              .instance(Map.of("petId", 1))
               .start()
               .join());
     }

impl/core/src/main/java/io/serverlessworkflow/impl/DefaultExecutorServiceFactory.java

@@ -21,12 +21,17 @@
 public class DefaultExecutorServiceFactory implements ExecutorServiceFactory {
 
   private static final ExecutorServiceFactory instance = new DefaultExecutorServiceFactory();
+  private static boolean serviceLoaded;
 
   public static ExecutorServiceFactory instance() {
     return instance;
   }
 
   private static class ExecutorServiceHolder {
+    static {
+      serviceLoaded = true;
+    }
+
     private static ExecutorService instance = Executors.newCachedThreadPool();
   }
 
@@ -36,4 +41,11 @@ public ExecutorService get() {
   }
 
   private DefaultExecutorServiceFactory() {}
+
+  @Override
+  public void close() {
+    if (serviceLoaded) {
+      ExecutorServiceHolder.instance.shutdownNow();
+    }
+  }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/ExecutorServiceFactory.java

@@ -18,5 +18,6 @@
 import java.util.concurrent.ExecutorService;
 import java.util.function.Supplier;
 
-@FunctionalInterface
-public interface ExecutorServiceFactory extends Supplier<ExecutorService> {}
+public interface ExecutorServiceFactory extends Supplier<ExecutorService>, AutoCloseable {
+  void close();
+}

impl/core/src/main/java/io/serverlessworkflow/impl/WorkflowApplication.java

@@ -39,7 +39,6 @@
 import java.util.ServiceLoader.Provider;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.stream.Collectors;
 
 public class WorkflowApplication implements AutoCloseable {
@@ -137,7 +136,7 @@ public SchemaValidator getValidator(SchemaInline inline) {
     private SchemaValidatorFactory schemaValidatorFactory;
     private WorkflowPositionFactory positionFactory = () -> new QueueWorkflowPosition();
     private WorkflowIdFactory idFactory = () -> UlidCreator.getMonotonicUlid().toString();
-    private ExecutorServiceFactory executorFactory = () -> Executors.newCachedThreadPool();
+    private ExecutorServiceFactory executorFactory = DefaultExecutorServiceFactory.instance();
     private EventConsumer<?, ?> eventConsumer = InMemoryEvents.get();
     private EventPublisher eventPublisher = InMemoryEvents.get();
     private RuntimeDescriptorFactory descriptorFactory =
@@ -236,6 +235,7 @@ public WorkflowDefinition workflowDefinition(Workflow workflow) {
 
   @Override
   public void close() {
+    executorFactory.close();
     for (WorkflowDefinition definition : definitions.values()) {
       definition.close();
     }