Unexpected behaviour with service tasks between parallel gateways

Issue Description:
The service tasks configured between parallel gateways are stuck abruptly without any exception.

Example Use case:

Here, both the parallel gateways are asynchronous & exclusive and service tasks A, B and C are also asynchronous and exclusive. However we observe a pattern where service tasks A and B are executed as expected and service task C is stuck without moving forward. ACT_RU_EXECUTION table is still pointing at service task C and not moving to suspension state. There are no timeouts from service task C and no trace to confirm that the service task has started it's execution.

NOTE: This issue is not consistent but happening quite a few times.

Code:
<?xml version="1.0" encoding="UTF-8"?> <definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:activiti="http://activiti.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.activiti.org/test"> <process id="myProcess" name="My process" isExecutable="true"> <startEvent id="startevent1" name="Start"></startEvent> <parallelGateway id="parallelgateway1" name="Parallel Gateway" activiti:async="true"></parallelGateway> <parallelGateway id="parallelgateway2" name="Parallel Gateway" activiti:async="true"></parallelGateway> <serviceTask id="servicetask1" name="Service Task A"></serviceTask> <serviceTask id="servicetask2" name="Service Task B"></serviceTask> <serviceTask id="servicetask3" name="Service Task C"></serviceTask> <sequenceFlow id="flow1" sourceRef="startevent1" targetRef="parallelgateway1"></sequenceFlow> <sequenceFlow id="flow2" sourceRef="parallelgateway1" targetRef="servicetask1"></sequenceFlow> <sequenceFlow id="flow3" sourceRef="parallelgateway1" targetRef="servicetask3"></sequenceFlow> <sequenceFlow id="flow4" sourceRef="servicetask1" targetRef="servicetask2"></sequenceFlow> <sequenceFlow id="flow5" sourceRef="servicetask3" targetRef="parallelgateway2"></sequenceFlow> <sequenceFlow id="flow6" sourceRef="servicetask2" targetRef="parallelgateway2"></sequenceFlow> <serviceTask id="servicetask4" name="Service Task D"></serviceTask> <sequenceFlow id="flow7" sourceRef="parallelgateway2" targetRef="servicetask4"></sequenceFlow> <endEvent id="endevent1" name="End"></endEvent> <sequenceFlow id="flow8" sourceRef="servicetask4" targetRef="endevent1"></sequenceFlow> </process> <bpmndi:BPMNDiagram id="BPMNDiagram_myProcess"> <bpmndi:BPMNPlane bpmnElement="myProcess" id="BPMNPlane_myProcess"> <bpmndi:BPMNShape bpmnElement="startevent1" id="BPMNShape_startevent1"> <omgdc:Bounds height="35.0" width="35.0" x="160.0" y="273.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="parallelgateway1" id="BPMNShape_parallelgateway1"> <omgdc:Bounds height="40.0" width="40.0" x="260.0" y="270.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="parallelgateway2" id="BPMNShape_parallelgateway2"> <omgdc:Bounds height="40.0" width="40.0" x="720.0" y="270.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="servicetask1" id="BPMNShape_servicetask1"> <omgdc:Bounds height="55.0" width="105.0" x="370.0" y="180.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="servicetask2" id="BPMNShape_servicetask2"> <omgdc:Bounds height="55.0" width="105.0" x="550.0" y="180.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="servicetask3" id="BPMNShape_servicetask3"> <omgdc:Bounds height="55.0" width="105.0" x="451.0" y="333.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="servicetask4" id="BPMNShape_servicetask4"> <omgdc:Bounds height="55.0" width="105.0" x="840.0" y="263.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNShape bpmnElement="endevent1" id="BPMNShape_endevent1"> <omgdc:Bounds height="35.0" width="35.0" x="1000.0" y="273.0"></omgdc:Bounds> </bpmndi:BPMNShape> <bpmndi:BPMNEdge bpmnElement="flow1" id="BPMNEdge_flow1"> <omgdi:waypoint x="195.0" y="290.0"></omgdi:waypoint> <omgdi:waypoint x="260.0" y="290.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow2" id="BPMNEdge_flow2"> <omgdi:waypoint x="280.0" y="270.0"></omgdi:waypoint> <omgdi:waypoint x="280.0" y="207.0"></omgdi:waypoint> <omgdi:waypoint x="370.0" y="207.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow3" id="BPMNEdge_flow3"> <omgdi:waypoint x="280.0" y="310.0"></omgdi:waypoint> <omgdi:waypoint x="280.0" y="360.0"></omgdi:waypoint> <omgdi:waypoint x="451.0" y="360.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow4" id="BPMNEdge_flow4"> <omgdi:waypoint x="475.0" y="207.0"></omgdi:waypoint> <omgdi:waypoint x="550.0" y="207.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow5" id="BPMNEdge_flow5"> <omgdi:waypoint x="556.0" y="360.0"></omgdi:waypoint> <omgdi:waypoint x="740.0" y="360.0"></omgdi:waypoint> <omgdi:waypoint x="740.0" y="310.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow6" id="BPMNEdge_flow6"> <omgdi:waypoint x="655.0" y="207.0"></omgdi:waypoint> <omgdi:waypoint x="740.0" y="207.0"></omgdi:waypoint> <omgdi:waypoint x="740.0" y="270.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow7" id="BPMNEdge_flow7"> <omgdi:waypoint x="760.0" y="290.0"></omgdi:waypoint> <omgdi:waypoint x="840.0" y="290.0"></omgdi:waypoint> </bpmndi:BPMNEdge> <bpmndi:BPMNEdge bpmnElement="flow8" id="BPMNEdge_flow8"> <omgdi:waypoint x="945.0" y="290.0"></omgdi:waypoint> <omgdi:waypoint x="1000.0" y="290.0"></omgdi:waypoint> </bpmndi:BPMNEdge> </bpmndi:BPMNPlane> </bpmndi:BPMNDiagram> </definitions>

Beginnen Sie damit, den bereitgestellten BPMN-Prozess mit asynchronen parallelen Gateways und den Service Tasks A, B und C zu reproduzieren. Untersuchen Sie anschließend den Ausführungszustand in ACT_RU_EXECUTION, wenn Service Task C ins Stocken gerät. Vergleichen Sie erfolgreiche und ins Stocken geratene Läufe, und betrachten Sie das Issue als erledigt, wenn die Ursache identifiziert ist, der Workflow zuverlässig abgeschlossen wird und das Verhalten durch einen Regressionstest abgedeckt ist.