JDO-857: TCK: add a JDO flag to configure parallelism factor

README.md

@@ -138,6 +138,7 @@ The *jdo-exectck* Maven plugin has the following options
 * -Djdo.tck.testrunner.details: Output mode for test run. Use one of: none, summary, flat, tree, verbose, testfeed. If `none`is selected, then only the summary and test failures are shown.
 * -Djdo.tck.testrunner.colors: Setting this parameter to *enable* displays colors in the junit result log file.
 * -Djdo.tck.parallel.execution: Setting this parameter to *false* will disable parallel exceution of tck test methods in parallel threads.
+* -Djdo.tck.parallel.config.dynamic.factor: Computes the desired parallelism based on the number of available processors/cores multiplied by the factor configuration parameter. Defaults to 0.6.
 * -Djdo.tck.datastore.supportsQueryCancel: Setting this parameter to *true* indicates whether the datastore supports query canceling.
 * -Dproject.lib.ext.directory: Location of third party libraries such as JNDI.
 * -Ddatabase.runtck.sysproperties: Properties to use in accessing database.

exectck/src/main/java/org/apache/jdo/exectck/Help.java

@@ -115,6 +115,10 @@ public void execute() throws MojoExecutionException, MojoFailureException {
     msg.append("* jdo.tck.parallel.execution:\n");
     msg.append(
         "  Setting this parameter to false will disable parallel exceution of tck test methods in parallel threads.\n");
+    msg.append("* jdo.tck.parallel.config.dynamic.factor:\n");
+    msg.append(
+        "  Computes the desired parallelism based on the number of available processors/cores "
+            + "multiplied by the factor configuration parameter. Defaults to 0.6.\n");
     msg.append("* jdo.tck.datastore.supportsQueryCancel:\n");
     msg.append(
         "  Setting this parameter to true indicates whether the datastore supports query canceling.\n");

exectck/src/main/java/org/apache/jdo/exectck/RunTCK.java

@@ -138,6 +138,13 @@ public class RunTCK extends AbstractTCKMojo {
   @Parameter(property = "jdo.tck.parallel.execution", defaultValue = "true", required = true)
   private boolean testParallelExecution;
 
+  /**
+   * Computes the desired parallelism based on the number of available processors/cores multiplied
+   * by factor configuration parameter.
+   */
+  @Parameter(property = "jdo.tck.parallel.config.dynamic.factor")
+  private String testParallelDynamicFactor;
+
   /** Whether the datastore supports query canceling. */
   @Parameter(property = "jdo.tck.datastore.supportsQueryCancel", required = false)
   private String datastoreSupportsQueryCancel;
@@ -555,6 +562,11 @@ private int executeTestClass(
     command.add("--details=" + testRunnerDetails);
     command.add("--config");
     command.add("junit.jupiter.execution.parallel.enabled=" + testParallelExecution);
+    if (testParallelDynamicFactor != null && !testParallelDynamicFactor.trim().isEmpty()) {
+      command.add("--config");
+      command.add(
+          "junit.jupiter.execution.parallel.config.dynamic.factor=" + testParallelDynamicFactor);
+    }
     // add Test classes
     for (String testClass : classesList) {
       // skip empty entries