Jenkinsfile: run JDK tests on same agent, preventing deadlocks.

Author: greenrobot-team

Jenkinsfile

@@ -65,46 +65,10 @@ pipeline {
             }
         }
 
-// Note: currently not using matrix build because if builds run in parallel they can block each other.
-// Maybe use throttle plugin?
-//         stage("test-jdks") {
-//             matrix {
-//                 axes {
-//                     axis {
-//                         name "TEST_JDK"
-//                         values "8", "16"
-//                     }
-//                 }
-//                 stages {
-//                     stage("test") {
-//                         // Set agent to start with new workspace to avoid Gradle compile issues on shared workspace
-//                         agent {
-//                             label 'java'
-//                         }
-//                         environment {
-//                             TEST_JDK = "${TEST_JDK}"
-//                         }
-//                         steps {
-//                             // "|| true" for an OK exit code if no file is found
-//                             sh 'rm tests/objectbox-java-test/hs_err_pid*.log || true'
-//                             // Note: do not run check task as it includes SpotBugs.
-//                             sh "./ci/test-with-asan.sh $gradleArgs $gitlabRepoArgs clean :tests:objectbox-java-test:test"
-//                         }
-//                         post {
-//                             always {
-//                                 junit '**/build/test-results/**/TEST-*.xml'
-//                                 archiveArtifacts artifacts: 'tests/*/hs_err_pid*.log', allowEmptyArchive: true  // Only on JVM crash.
-//                             }
-//                         }
-//                     }
-//                 }
-//             }
-//         }
+        // Test oldest supported and a recent JDK.
+        // Note: can not run these in parallel using a matrix configuration as Gradle would step over itself.
+        // Also shouldn't add agent config to avoid that as it triggers a separate job which can easily cause deadlocks.
         stage("test-jdk-8") {
-            // Set agent to start with new workspace to avoid Gradle compile issues on shared workspace
-            agent {
-                label 'java'
-            }
             environment {
                 TEST_JDK = "8"
             }
@@ -122,10 +86,6 @@ pipeline {
             }
         }
         stage("test-jdk-16") {
-            // Set agent to start with new workspace to avoid Gradle compile issues on shared workspace
-            agent {
-                label 'java'
-            }
             environment {
                 TEST_JDK = "16"
             }