Cannot use CancellationToken to end orchestrator function - .net-core

Question

I am using an orchestration to await two sub-orchestrations which are executing in parallel or a timeout of 5min, whatever comes first. I am passing a CancellationToken to the sub-orchestrators and therein throw on cancellation using token.ThrowIfCancellationRequested(). Also, since I have created a timer in the main orchestrator function, I am responsible to clear it in the case the timeout is not triggered itself. This is documented here.
main orchestrator:
public class Fxbm_workflow
{
[FunctionName(nameof(Fxbm_workflow))]
public async Task Run([OrchestrationTrigger] IDurableOrchestrationContext ctx, ILogger log)
{
log = ctx.CreateReplaySafeLogger(log);
var parentWorkflowId = ctx.InstanceId;
var trigger = ctx.GetInput<Trigger<OrchestrationInput2>>();
using var cts = new CancellationTokenSource();
var expireIn = ctx.CurrentUtcDateTime.AddMinutes(5);
var responseTasks = new [] {327, 41}.Select(id => {
var input = (id, cts.Token);
var childWorkflowId = $"{parentWorkflowId}_{nameof(Fxbm_receive_response_workflow)}_{id}";
return ctx.CallSubOrchestratorAsync<object>(nameof(Fxbm_receive_response_workflow), instanceId: childWorkflowId, input: input);
});
var timeoutTask = ctx.CreateTimer(expireIn, cts.Token);
// await tasks, choose winner
var winner = await Task.WhenAny(Task.WhenAll(responseTasks), timeoutTask);
if (winner == timeoutTask)
{
log.LogWarning("winner= timeout");
// no need to cts.Cancel() here
}
else
{
log.LogWarning("winner= all tasks have finished before the timeout");
cts.Cancel();
}
}
}
sub-orchestrator function:
public class Fxbm_receive_response_workflow
{
[FunctionName(nameof(Fxbm_receive_response_workflow))]
public async Task<object> Run([OrchestrationTrigger] IDurableOrchestrationContext ctx, ILogger log)
{
log = ctx.CreateReplaySafeLogger(log);
var (clientId, token) = ctx.GetInput<(int, CancellationToken)>();
token.ThrowIfCancellationRequested();
log.LogWarning($"waiting for response of clientId= {clientId}");
var evnt = await ctx.WaitForExternalEvent<object>(name: clientId.ToString());
log.LogWarning($"response received for clientId= {clientId}");
await ctx.CallActivityAsync(nameof(Fxbm_notifyOfNewReport), evnt);
return evnt;
}
}
However, this doesn't work. In the screenshot below there's the execution history extracted using DfMon. One of the two sub-orchestrations completes successfully. Before the other one can finish, the 5min timeout is triggered. Still, neither does the remaining sub-orchestration fail (due to token.ThrowIfCancellationRequested()), nor does the parent orchestration complete, inspite of calling cts.Cancel(). Both are still in a Running state.
It is my understanding the sub-orchestration should have failed/thrown and the parent orchestration should have concluded successfully. Does someone know why this is not the case here? Since orchestrator functions are re-executed again and again until finished, I do worry about unncessary $$$ cost of this when deployed in Azure.