improve: use fixed thread pool explicitly

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ConfigurationService.java

@@ -4,6 +4,7 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.function.Consumer;
 
 import org.slf4j.Logger;
@@ -24,8 +25,6 @@
 import io.javaoperatorsdk.operator.processing.dependent.kubernetes.KubernetesDependent;
 import io.javaoperatorsdk.operator.processing.dependent.workflow.ManagedWorkflowFactory;
 
-import static io.javaoperatorsdk.operator.api.config.ExecutorServiceManager.newThreadPoolExecutor;
-
 /** An interface from which to retrieve configuration information. */
 public interface ConfigurationService {
 
@@ -127,14 +126,18 @@ default boolean checkCRDAndValidateLocalModel() {
     return false;
   }
 
-  int DEFAULT_RECONCILIATION_THREADS_NUMBER = 200;
+  int DEFAULT_RECONCILIATION_THREADS_NUMBER = 50;
+  /**
+   * @deprecated Not used anymore in the default implementation
+   */
+  @Deprecated(forRemoval = true)
   int MIN_DEFAULT_RECONCILIATION_THREADS_NUMBER = 10;
 
   /**
-   * The maximum number of threads the operator can spin out to dispatch reconciliation requests to
-   * reconcilers
+   * The number of threads the operator can spin out to dispatch reconciliation requests to
+   * reconcilers with the default executors
    *
-   * @return the maximum number of concurrent reconciliation threads
+   * @return the number of concurrent reconciliation threads
    */
   default int concurrentReconciliationThreads() {
     return DEFAULT_RECONCILIATION_THREADS_NUMBER;
@@ -143,17 +146,24 @@ default int concurrentReconciliationThreads() {
   /**
    * The minimum number of threads the operator starts in the thread pool for reconciliations.
    *
+   * @deprecated not used anymore by default executor implementation
    * @return the minimum number of concurrent reconciliation threads
    */
+  @Deprecated(forRemoval = true)
   default int minConcurrentReconciliationThreads() {
     return MIN_DEFAULT_RECONCILIATION_THREADS_NUMBER;
   }
 
   int DEFAULT_WORKFLOW_EXECUTOR_THREAD_NUMBER = DEFAULT_RECONCILIATION_THREADS_NUMBER;
+  /**
+   * @deprecated Not used anymore in the default implementation
+   */
+  @Deprecated(forRemoval = true)
   int MIN_DEFAULT_WORKFLOW_EXECUTOR_THREAD_NUMBER = MIN_DEFAULT_RECONCILIATION_THREADS_NUMBER;
 
   /**
-   * Retrieves the maximum number of threads the operator can spin out to be used in the workflows.
+   * Number of threads the operator can spin out to be used in the workflows with the default
+   * executor.
    *
    * @return the maximum number of concurrent workflow threads
    */
@@ -164,8 +174,10 @@ default int concurrentWorkflowExecutorThreads() {
   /**
    * The minimum number of threads the operator starts in the thread pool for workflows.
    *
+   * @deprecated not used anymore by default executor implementation
    * @return the minimum number of concurrent workflow threads
    */
+  @Deprecated(forRemoval = true)
   default int minConcurrentWorkflowExecutorThreads() {
     return MIN_DEFAULT_WORKFLOW_EXECUTOR_THREAD_NUMBER;
   }
@@ -191,13 +203,11 @@ default Metrics getMetrics() {
   }
 
   default ExecutorService getExecutorService() {
-    return newThreadPoolExecutor(minConcurrentReconciliationThreads(),
-        concurrentReconciliationThreads());
+    return Executors.newFixedThreadPool(concurrentReconciliationThreads());
   }
 
   default ExecutorService getWorkflowExecutorService() {
-    return newThreadPoolExecutor(minConcurrentWorkflowExecutorThreads(),
-        concurrentWorkflowExecutorThreads());
+    return Executors.newFixedThreadPool(concurrentWorkflowExecutorThreads());
   }
 
   default boolean closeClientOnStop() {

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ConfigurationServiceOverrider.java

@@ -218,13 +218,21 @@ public int concurrentWorkflowExecutorThreads() {
             original.concurrentWorkflowExecutorThreads());
       }
 
+      /**
+       * @deprecated Not used anymore in the default implementation
+       */
+      @Deprecated(forRemoval = true)
       @Override
       public int minConcurrentReconciliationThreads() {
         return minConcurrentReconciliationThreads != null ? minConcurrentReconciliationThreads
             : original.minConcurrentReconciliationThreads();
       }
 
+      /**
+       * @deprecated Not used anymore in the default implementation
+       */
       @Override
+      @Deprecated(forRemoval = true)
       public int minConcurrentWorkflowExecutorThreads() {
         return minConcurrentWorkflowExecutorThreads != null ? minConcurrentWorkflowExecutorThreads
             : original.minConcurrentWorkflowExecutorThreads();

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ExecutorServiceManager.java

@@ -8,8 +8,6 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
-import java.util.concurrent.LinkedBlockingDeque;
-import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.function.Function;
@@ -35,14 +33,6 @@ public class ExecutorServiceManager {
     start(configurationService);
   }
 
-  public static ExecutorService newThreadPoolExecutor(int minThreads, int maxThreads) {
-    minThreads = Utils.ensureValid(minThreads, "minimum number of threads", MIN_THREAD_NUMBER);
-    maxThreads = Utils.ensureValid(maxThreads, "maximum number of threads", minThreads + 1);
-
-    return new ThreadPoolExecutor(minThreads, maxThreads, 1, TimeUnit.MINUTES,
-        new LinkedBlockingDeque<>());
-  }
-
   /**
    * Uses cachingExecutorService from this manager. Use this only for tasks, that don't have dynamic
    * nature, in sense that won't grow with the number of inputs (thus kubernetes resources)

operator-framework-core/src/test/java/io/javaoperatorsdk/operator/processing/event/EventProcessorTest.java

@@ -434,7 +434,6 @@ void executionOfReconciliationShouldNotStartIfProcessorStopped() throws Interrup
         new BaseConfigurationService(),
         o -> {
           o.withConcurrentReconciliationThreads(1);
-          o.withMinConcurrentReconciliationThreads(1);
         });
     eventProcessor =
             spy(new EventProcessor(controllerConfiguration(null, rateLimiterMock, configurationService),