One way should be to use Alteryx Server API to check if the apps has already been put in queue in the server or is being executed by another user.
You can read more information on how to use Alteryx Server Api within your workflow here.
Another solution would be to create a "flag" (in a file for example) and to put a boolean value inside (1) when you begin the workflow and (0) at the end. You check this value prior to launch your process: if 0 then you continue else you stop. But you have to manage the fact that if your workflow crash, the value will not be put at 0 and the next execution will not be possible (so add a timestamp information to evaluate this situation).
Perhaps, there is a more smart solution.
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
