UNKNOWN GRPC error on describe in TestWorkflowEnvironment

[jeffschoner-stripe]

Expected Behavior

Calling describe on the workflow should return a valid result.

Actual Behavior

Calling describe on the workflow sometimes results in a GRPC exception being thrown.

io.grpc.StatusRuntimeException: UNKNOWN
	at io.grpc.stub.ClientCalls.toStatusRuntimeException(ClientCalls.java:271)
	at io.grpc.stub.ClientCalls.getUnchecked(ClientCalls.java:252)
	at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:165)
	at io.temporal.api.workflowservice.v1.WorkflowServiceGrpc$WorkflowServiceBlockingStub.describeWorkflowExecution(WorkflowServiceGrpc.java:5523)

Steps to Reproduce the Problem

There are not reliable repro steps. The issue is intermittent.

In a JUnit test,

1. Set up a TestWorkflowEnvironment. This is being done in a @BeforeClass method in a base class for the unit test class. All instances are stored in class variables for the life of the test. It's not clear to me if the static/class methods/variables are playing a role here or not.
2. In a @Before method on the class with the unit tests,
   - Start a workflow. This is done indirectly in that our test is calling a GRPC endpoint that is also running inside the test which starts a workflow. However, the starting of the workflow is done synchronously back to the caller. It's not clear to me that the indirection here matters.
   - Call DescribeWorkflowExecution using the workflow ID that was used in the previous step

Specifications

• Version: 1.27.1
• Platform: Linux

[Quinn-With-Two-Ns]

Thanks for the report we will investigate

[Quinn-With-Two-Ns]

So likely this error means some exception (that is not a StatusRuntimeException) was thrown while running describeWorkflowExecution. Since that is the most common way the client would receive an UNKNOWN status. I was also able to manually confirm by adding a throw new IllegalArgumentException("test") to the top of the above function. The SDK would log the exception so can you share any logs from these failed tests? The exception would look like this based on my test I described above.

Sep 15, 2025 10:19:50 A.M. io.grpc.internal.SerializingExecutor run
SEVERE: Exception while executing runnable io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed@72a7e903
java.lang.IllegalArgumentException: test
	at io.temporal.internal.testservice.TestWorkflowMutableStateImpl.describeWorkflowExecution(TestWorkflowMutableStateImpl.java:3154)
	at io.temporal.internal.testservice.TestWorkflowService.describeWorkflowExecution(TestWorkflowService.java:1691)
	at io.temporal.api.workflowservice.v1.WorkflowServiceGrpc$MethodHandlers.invoke(WorkflowServiceGrpc.java:8975)
	at io.grpc.stub.ServerCalls$UnaryServerCallHandler$UnaryServerCallListener.onHalfClose(ServerCalls.java:182)
	at io.grpc.PartialForwardingServerCallListener.onHalfClose(PartialForwardingServerCallListener.java:35)
	at io.grpc.ForwardingServerCallListener.onHalfClose(ForwardingServerCallListener.java:23)
	at io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:351)
	at io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed.runInContext(ServerImpl.java:860)
	at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
	at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1583)

[jeffschoner-stripe]

@Quinn-With-Two-Ns Thanks for the pointer on what to look for. Here's the stack trace of one of the failures. Looks like it may be some sort race condition with child workflows

00:12:24.820	SEVERE: Exception while executing runnable io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed@77c3bde9
00:12:24.820	java.lang.NullPointerException: Cannot invoke "io.temporal.api.common.v1.WorkflowExecution.getWorkflowId()" because "data.execution" is null
00:12:24.820		at io.temporal.internal.testservice.TestWorkflowMutableStateImpl.constructPendingChildExecutionInfo(TestWorkflowMutableStateImpl.java:3115)
00:12:24.820		at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
00:12:24.820		at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
00:12:24.820		at java.base/java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1779)
00:12:24.820		at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
00:12:24.820		at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
00:12:24.820		at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
00:12:24.820		at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
00:12:24.820		at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
00:12:24.820		at io.temporal.internal.testservice.TestWorkflowMutableStateImpl.describeWorkflowExecutionInsideLock(TestWorkflowMutableStateImpl.java:3099)
00:12:24.820		at io.temporal.internal.testservice.TestWorkflowMutableStateImpl.describeWorkflowExecution(TestWorkflowMutableStateImpl.java:3030)
00:12:24.820		at io.temporal.internal.testservice.TestWorkflowService.describeWorkflowExecution(TestWorkflowService.java:1584)
00:12:24.820		at io.temporal.api.workflowservice.v1.WorkflowServiceGrpc$MethodHandlers.invoke(WorkflowServiceGrpc.java:7312)
00:12:24.820		at io.grpc.stub.ServerCalls$UnaryServerCallHandler$UnaryServerCallListener.onHalfClose(ServerCalls.java:182)
00:12:24.820		at io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:354)
00:12:24.820		at io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed.runInContext(ServerImpl.java:866)
00:12:24.820		at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
00:12:24.820		at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)
00:12:24.820		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
00:12:24.820		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
00:12:24.820		at java.base/java.lang.Thread.run(Thread.java:840)

In the older version of the code we're running, it's in this function in TestWorkflowMutableStateImpl.java:

  private static PendingChildExecutionInfo constructPendingChildExecutionInfo(
      StateMachine<ChildWorkflowData> sm) {
    ChildWorkflowData data = sm.getData();
    return PendingChildExecutionInfo.newBuilder()
        .setWorkflowId(data.execution.getWorkflowId())
        .setRunId(data.execution.getRunId())
        .setWorkflowTypeName(data.initiatedEvent.getWorkflowType().getName())
        .setInitiatedId(data.initiatedEventId)
        .setParentClosePolicy(data.initiatedEvent.getParentClosePolicy())
        .build();
  }