DesignBoard

The dynamic behaviour can’t be extracted from the code; one has to run it. Often this is done by manually following the most important functions. (So, not by executing it – that gives way to many details).

A very convenient procedure is to write-down the essential lines of the method. And of the methods that are being called. Use “arrows” to denote the (data & control) flow and to connect the pieces. Elaborate when needed.
By using a big whiteboard and many colors (and a wiper!) the “flow” can be visualised.

See my analyse in this picture below.

../../../../_images/TPE_Analyse.jpg

Next, this “curly flow” can be converted to a sequence-diagram. Preferable on a 2nd whiteboard. As shown below.

../../../../_images/TPE_sequence.jpg

Last, and optional, we can convert it to (plant)UML:

@startuml hide footbox !pragma teoz true participant TPE participant "Future(s)" as Future <<data>> participant "WorkItem(s)" as WorkItem <<data>> participant "WorkQueue" as Queue control "WorkersPool" as Workers <<Threads>> note right of Workers: max ""max_workers"" independent worker threads == Initialisation == [-> TPE: ThreadPoolExecutor(max_workers) TPE -> Queue: self._work_queue = Queue() == Once == [-> TPE: **submit**(__func__, args, kwargs) TPE ->o Future: f=Future() TPE ->o WorkItem: w=WorkItem(f, func, args,kwargs) TPE -> Queue: put(w) par group if less as max_workers note right of Workers: in _adjust_thread_count() TPE -> Workers: Threads(target=Workers, self._work_queue), start activate Workers end [/-- TPE: //future// [-\ Future: future.result(~~timeout=None~~) activate Future else Workers -\ Queue: get(~~block=True~~) Queue --> Workers: WorkItem Workers -> WorkItem: run activate WorkItem WorkItem -> WorkItem: result=__func__(args,kwargs) WorkItem -> Future: set(result) deactivate WorkItem end [<-- Future: value deactivate Future == Many == note over TPE, WorkItem: Details for TPE as above note over Future, Workers: ThreadPool: assume three independent workers (""max_workers == 3"")\nFor details, see above. get ... set in a forever-loop par note right of Workers: worker-1 Workers -\ Queue: get(~~block=True~~) else [-> TPE: 2) **submit** TPE -> Queue: put(w) TPE -> Workers: Threads(target=Workers, self._work_queue), start activate Workers [/-- TPE: //future_2// [-> TPE: 3) **submit** TPE -> Queue: put(w) TPE -> Workers: Threads(target=Workers, self._work_queue), start activate Workers [/-- TPE: //future_3// [-> TPE: 4) **submit** TPE -> Queue: put(w) [/-- TPE: //future_4// else note right of Workers: worker-1\n(~~unblock~~) Queue --> Workers: WorkItem Workers -> WorkItem: run activate WorkItem WorkItem -> Future: set(result) deactivate WorkItem else note right of Workers: worker-2 Workers -\ Queue: WorkItem = get(~~block=True~~) Workers -> WorkItem: run activate WorkItem WorkItem -> Future: set(result) deactivate WorkItem else note right of Workers: worker-3 Workers -\ Queue: WorkItem = get(~~block=True~~) Workers -> WorkItem: run activate WorkItem WorkItem -> Future: set(result) deactivate WorkItem end note right of Workers: a worker\n(as soon as one is available) Workers -\ Queue: WorkItem = get(~~block=True~~) Workers -> WorkItem: run activate WorkItem WorkItem -> Future: set(result) deactivate WorkItem ||| @enduml

(also see pregen-backup)

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