gRPC Client call switches from event-loop thread to executor thread

[senthilredhat]

I have a gRPC service calling another gRPC service. During response transformation, the thread switches from an event loop to an executor thread. After the gRPC call, the code tries to access Mutiny.session, which throws an error because the thread is an executor thread.

What can I do to avoid thread switching?

public Uni<Boolean> check(Relationship relationship) {
    if (!permissionCheckerEnabled)
        return Uni.createFrom().item(Boolean.TRUE);
    System.out.println("com.fga.SpiceDBRelationShipManager.check **" + Thread.currentThread().getName());
    return permissionsServiceStub.checkPermission(permissionRequestFromRelationship(relationship))
            .onItem().transform(checkPermissionResponse -> {
                System.out.println("com.fga.SpiceDBRelationShipManager.check.transform **" + Thread.currentThread().getName());
                return isPermitted(checkPermissionResponse);
            })
            .onFailure().recoverWithNull();
}

In the above code, permissionsServiceStub is a gRPC service,

Here are the sys outs from the above code during the execution

com.fga.SpiceDBRelationShipManager.check **vert.x-eventloop-thread-1
com.fga.SpiceDBRelationShipManager.check.transform **grpc-default-executor-0