Maxon Developers Maxon Developers
    • Documentation
      • Cinema 4D Python API
      • Cinema 4D C++ API
      • Cineware API
      • ZBrush GoZ API
      • Code Examples on Github
    • Forum
    • Downloads
    • Support
      • Support Procedures
      • Registered Developer Program
      • Plugin IDs
      • Contact Us
    • Categories
      • Overview
      • News & Information
      • Cinema 4D SDK Support
      • Cineware SDK Support
      • ZBrush 4D SDK Support
      • Bugs
      • General Talk
    • Unread
    • Recent
    • Tags
    • Users
    • Login

    Best plugin type for background (thread) processing?

    Cinema 4D SDK
    r20 python
    6
    16
    3.0k
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • H
      heilei
      last edited by

      The examples Maxon has in GitHub include "Py-TextureBaker", which seems to use threads. I'm currently going through that code (and trying to understand it...), because I'm facing the exact same challenge as OP: how to start something in a thread, and make that thread send messages to other plugins.

      P 1 Reply Last reply Reply Quote 1
      • lasselauchL
        lasselauch
        last edited by

        Yeah, I'm looking into this as well...

        Ideally I want to run different function with a decorator: @execute_on_own_thread which would be very convenient.

        1 Reply Last reply Reply Quote 1
        • P
          pim @heilei
          last edited by

          @heilei said in Best plugin type for background (thread) processing?:

          Py-TextureBaker

          That is a very good working example.
          I rebuild my plugin using py-texturebaker and now it is working!

          After some studying, I think @PluginStudent is fully correct when referring to the global scope.

          @PluginStudent said in Best plugin type for background (thread) processing?:

          Please read my post above and the C4DThread Manual carefully.

          You can start the thread in a CommandData plugin. But this plugin must not own the thread instance. The thread instance should be stored in the global scope.

          In the MessageData plugin, you should react to a core message sent from the thread. Nothing else; no creation or waiting.

          I guess it is working because in the dialog the thread class is initiated.
          textureBakerThread = None
          and further in the code it is referenced with self.textureBakerThread.

          I was using

                  thread = UserThread()
                  thread.Start()
          

          Everybody thanks for all the help.

          1 Reply Last reply Reply Quote 1
          • M
            m_adam
            last edited by

            Hi @pim this is very different, texture baker will execute a specific command in a thread (So you execute it only at a given time) while in your case if I understood correctly you want something that runs in the background.

            So here a general example that runs a thread in background and updates a GeDialog according to some random event. This is a very generic solution, in your case, the proper way would be to handle the thread creation, not within the C4DPL_PROGRAM_STARTED but in the init method of the GeDialog and end the thread in the AskClose method of the GeDialog. But since I wanted to demonstrate something very generic I used C4DPL_PROGRAM_STARTED and C4DPL_ENDACTIVITY so the thread will exist as long as Cinema 4D start and exit.

            import c4d
            import time, random, weakref
            
            PLUGIN_ID_COMMAND_DATA = 1000000
            
            # Store the global thread
            GlobalThread = None
            
            # Store a weakref of the GeDialog
            GlobalDialog = None
            
            # Background Thread is driven from Thread class to make it run in the background.
            class BGThread(c4d.threading.C4DThread):
                end = False
            
                # Called by TestBreak to adds a custom condition to leave
                def TestDBreak(self):
                    return bool(self.end) 
            
                def GenerateBitmap(self):
                    "Generate a basebitmap with a random color"
                    clipMap = c4d.bitmaps.GeClipMap()
                    clipMap.Init(100, 100)
                    clipMap.BeginDraw()
                    clipMap.SetColor(int(random.random() * 255 ), int(random.random() * 255 ), int(random.random() * 255 ))
                    clipMap.FillRect(0, 0, 100, 100)
                    clipMap.EndDraw()
            
                    # It's important to return a clone since the original basebtimap is owned by the GeClipMap.
                    # So if the GeClipMap is destructed (and it will be the case after the return statement), the BaseBtimap will also be destructed.
                    return clipMap.GetBitmap().GetClone()
            
                # Starts the thread to start listing to the port.
                def Main(self):
                    while True:
            
                        # Checks if the thread needs to be closed e.g. a call of GlobalThread.End()
                        if self.TestBreak():
                            return
            
                        # Sleeps to not support 
                        time.sleep(0.1)
            
                        # Retrieves the global variable and either check if there is no Dialog, or if the weakref is None
                        global GlobalDialog
                        if GlobalDialog is None or GlobalDialog() is None:
                            continue
            
                        dlg = GlobalDialog()
                        if not dlg.IsOpen():
                            continue
                        
                        # Simulates a random update
                        randomEvent = bool(random.randint(1, 100) <= 10)
                        if randomEvent:
                            bmp = self.GenerateBitmap()
            
                            # I use a try/Except block, because we are in a threaded environment, so even if I check previously if the dialog exists
                            # it's not 100% thread-safe, since the user may have closed the UI between the previous stuff.
                            try:
                                GlobalDialog().UpdatePicture(bmp)
                            except:
                                pass
            
            # The Dialog class
            class DialogWithBitmap(c4d.gui.GeDialog):
                
                def __init__(self):
                    global GlobalDialog
                    GlobalDialog = weakref.ref(self)
            
                    self.bmp = None
                    self.customUiBmp = None
            
                # Define our Layout
                def CreateLayout(self):
                    w = c4d.gui.SizePix(100)
                    h = c4d.gui.SizePix(100)
            
                    bcBitmapButton = c4d.BaseContainer()
                    bcBitmapButton[c4d.BITMAPBUTTON_BUTTON] = True
                    bcBitmapButton[c4d.BITMAPBUTTON_BORDER] = c4d.BORDER_IN
            
                    self.customUiBmp = self.AddCustomGui(1000, c4d.CUSTOMGUI_BITMAPBUTTON, "", c4d.BFH_FIT|c4d.BFV_TOP, w, h, bcBitmapButton)    
                    return True
            
                def UpdatePicture(self, bmp):
                    # Called from the thread
                    self.bmp = bmp
            
                    # Sanity checks if the dialog is opened or eitehr the customUI is not defined
                    if self.IsOpen() and self.customUiBmp is not None:
            
                        self.customUiBmp.SetImage(self.bmp)
                        if c4d.threading.GeIsMainThread():
                            self.customUiBmp.Redraw()
                        else:
                            # If we are not on the main thread, redraw is not allowed, so add a special event with a unique ID
                            c4d.SpecialEventAdd(PLUGIN_ID_COMMAND_DATA, 0, 0)
                    return True
            
                def CoreMessage(self, id, msg):
                    if id == PLUGIN_ID_COMMAND_DATA:
                        self.customUiBmp.Redraw()
                    return True
            
            
            # The CommandData plugin which host the Dialog object alive
            class CommandDataDlg(c4d.plugins.CommandData):
                dialog = None
            
                def Execute(self, doc):
                    if self.dialog is None:
                        self.dialog = DialogWithBitmap()
                    return self.dialog.Open(dlgtype=c4d.DLG_TYPE_ASYNC, pluginid=PLUGIN_ID_COMMAND_DATA, xpos=-1, ypos=-1, defaultw=200, defaulth=150)
            
                def RestoreLayout(self, sec_ref):
                    if self.dialog is None:
                        self.dialog = DialogWithBitmap()
                    return self.dialog.Restore(pluginid=PLUGIN_ID_COMMAND_DATA, secret=sec_ref)
            
            
            # Handle our thread here
            def PluginMessage(id, data):
                global GlobalThread
            
                # At the start of Cinema 4D We lunch our thread
                if id == c4d.C4DPL_PROGRAM_STARTED:
                    GlobalThread = BGThread()
                    GlobalThread.Start()
            
                # At the end we clean our Thread + BC used to pass data
                elif id == c4d.C4DPL_ENDACTIVITY:
                    if GlobalThread:
                        GlobalThread.end = True
                        GlobalThread.End()
            
            
            # Main function
            def main():
                c4d.plugins.RegisterCommandPlugin(PLUGIN_ID_COMMAND_DATA, "GeDialog Example", 0, None, "GeDialog Example", CommandDataDlg())
            
            # Execute main()
            if __name__=='__main__':
                main()
            

            However your suggestion @lasselauch is very nice, so I will take care of it when I will come back from vacation.
            Note that due to the nature of Python, there is no real Multi-threading so don't expect performance boost, ( in reality you will only have a decreasing of performance, its better to use async stuff). The scope of thread in python is like the one in Example where you have something multiple things to do at the same time without the need to block everything, like GUI.
            I'm going to leave on vacation and should come back Monday, I will try to clean up the previous code and make it as an example and also an example about your decorator idea @lasselauch.

            Cheers,
            Maxime.

            MAXON SDK Specialist

            Development Blog, MAXON Registered Developer

            P 1 Reply Last reply Reply Quote 1
            • lasselauchL
              lasselauch
              last edited by

              Nice, thanks for the example @m_adam ! Have a great vacation and looking forward to the decorator example!

              BTW – This example might come in handy if we want to integrate animated images, kinda a like a gif but based on an image-sequence... hmmm, I have to think about this! 🙂

              Thanks & Cheers,
              Lasse

              1 Reply Last reply Reply Quote 0
              • P
                pim @m_adam
                last edited by

                @m_adam said in Best plugin type for background (thread) processing?:

                ( in reality you will only have a decreasing of performance, its better to use async stuff).

                Thanks for the example.
                Could you also clarify a bit more for me, how to improve performance (async stuff)?

                M 1 Reply Last reply Reply Quote 0
                • M
                  mp5gosu
                  last edited by

                  @m_adam I have a question about the following portion of your code:

                      # At the end we clean our Thread + BC used to pass data
                      elif id == c4d.C4DPL_ENDACTIVITY:
                          if GlobalThread:
                              GlobalThread.end = True # 1
                              GlobalThread.End() # 2
                  

                  Aren't 1 & 2 not redundant in this case?
                  TestDBreak() tests for self.end which is satisfied in the above example and therefore TestBreak() also returns True, so the thread exists.
                  Why the additional call to End()?

                  What am I missing here?

                  Cheers,
                  Robert

                  1 Reply Last reply Reply Quote 0
                  • M
                    m_adam @pim
                    last edited by m_adam

                    Hi @mp5gosu
                    Correct, it was just to demonstrate a possible usage.
                    The next code would not have the same sense since .end will be checked only the next TestDBreak is called, while End(False) will force the thread to be ended right now.

                    GlobalThread.end = True # 1
                    GlobalThread.End(False) # 2
                    

                    @lasselauch Here an implementation example of an execute_on_own_thread decorator.

                    import c4d
                    import functools
                    import time
                    import random
                    
                    global globalThreadStorage
                    globalThreadStorage = []
                    
                    
                    class BGThread(c4d.threading.C4DThread):
                    
                        def __init__(self, func, *args, **kwargs):
                            self.func = func
                            self.args = args
                            self.kwargs = kwargs
                    
                        def Main(self):
                            self.func(*self.args, **self.kwargs)
                            return
                    
                    
                    class CleanupThread(c4d.threading.C4DThread):
                    
                        def Main(self):
                            while True:
                                time.sleep(3)
                    
                                c4d.threading.GeThreadLock()
                                global globalThreadStorage
                    
                                # If there is only 1 thread in the global list and its self, leave since there is nothing else to clean.
                                if len(globalThreadStorage) == 1 and globalThreadStorage[0] == self:
                                    c4d.threading.GeThreadUnlock()
                                    return
                    
                                # Removes all threads that are finished, so the garbage collector can delete them.
                                for thread in reversed(globalThreadStorage):
                                    if not thread.IsRunning():
                                        thread.End(False)
                                        globalThreadStorage.remove(thread)
                    
                                c4d.threading.GeThreadUnlock()
                    
                                if self.TestBreak():
                                    return
                    
                            return
                    
                    
                    # Creates the decorator with argument
                    def execute_on_own_thread(wait=False):
                    
                        # The decorated function
                        def decorated(func):
                            @functools.wraps(func)
                    
                            # The wrapper
                            def wrapper(*args, **kwargs):
                                thread = BGThread(func, *args, **kwargs)
                                thread.Start()
                    
                                # If we don't wait for the thread to be finalized, that means the created thread should live even after
                                # this function is executed. So we store a thread reference in a global list and we also initialize
                                # the cleanup thread, which as its name suggest will have the role to delete other thread.
                                if not wait:
                                    c4d.threading.GeThreadLock()
                    
                                    # Adds the thread that encapsulates the function to the global list
                                    global globalThreadStorage
                                    globalThreadStorage.append(thread)
                    
                                    # Checks if there is already a cleanup thread, and if not create it
                                    cleanupThreadPresent = False
                                    for thread in globalThreadStorage:
                                        if isinstance(thread, CleanupThread):
                                            cleanupThreadPresent = True
                                            break
                    
                                    if not cleanupThreadPresent:
                                        cleanupThread = CleanupThread()
                                        cleanupThread.Start()
                                        globalThreadStorage.append(cleanupThread)
                    
                                    c4d.threading.GeThreadUnlock()
                    
                                if wait:
                                    thread.End(wait)
                                    del thread
                    
                                return
                            return wrapper
                        return decorated
                    
                    
                    @execute_on_own_thread(False)
                    def randomAction(a):
                        rTime = random.random() * 5
                        time.sleep(rTime)
                        print(a, rTime)
                    
                    
                    def main():
                        for x in xrange(10):
                            randomAction(x)
                    
                        print("main done")
                    
                    # Execute main()
                    if __name__=='__main__':
                        main()
                    

                    @pim Here a safer and appropriate version for a GeDialog background thread, this does not rely on a global variable but only live as long as the dialog object lives while my previous example was something genric.

                    import c4d
                    import time, random, weakref
                    
                    PLUGIN_ID_COMMAND_DATA = 1000000
                    
                    # Background Thread is driven from Thread class to make it run in the background.
                    class BGThread(c4d.threading.C4DThread):
                    
                        def __init__(self, dlg):
                            self.dlg = weakref.ref(dlg)
                    
                        def GenerateBitmap(self):
                            # Generate a basebitmap with a random color"
                            clipMap = c4d.bitmaps.GeClipMap()
                            clipMap.Init(100, 100)
                            clipMap.BeginDraw()
                            clipMap.SetColor(int(random.random() * 255), int(random.random() * 255), int(random.random() * 255))
                            clipMap.FillRect(0, 0, 100, 100)
                            clipMap.EndDraw()
                    
                            # It's important to return a clone since the original basebtimap is owned by the GeClipMap.
                            # So if the GeClipMap is destructed (and it will be the case after the return statement), the BaseBtimap will also be destructed.
                            return clipMap.GetBitmap().GetClone()
                    
                        # Starts the thread to start listing to the port.
                        def Main(self):
                    
                            while True:
                                # Creates a global try/except block since at any time the dlg can be destructed.
                                try:
                                    # Checks if the thread needs to be closed e.g. a call of GlobalThread.End()
                                    if self.TestBreak():
                                        return
                    
                                    # Sleeps to not bother too much the CPU
                                    time.sleep(0.1)
                    
                                    if not self.dlg().IsOpen():
                                        continue
                    
                                    # Simulates a random update
                                    randomEvent = bool(random.randint(1, 100) <= 10)
                                    if randomEvent:
                                        bmp = self.GenerateBitmap()
                                        self.dlg().UpdatePicture(bmp)
                    
                                # Catch the case self.dlg() return None, because the dlg object is destructed.
                                # This should not happen because in the dialog.__del__ method, this thread is ended.
                                # This also why a weakref is used, cause if the thread store directly a ref to the GeDialog,
                                # Due to Python refcounting, the Dialog will never be deleted, so __end__ will never be called.
                                except AttributeError:
                                    return
                    
                    
                    # The Dialog class
                    class DialogWithBitmap(c4d.gui.GeDialog):
                    
                        def __init__(self):
                            self.thread = BGThread(self)
                            self.thread.Start()
                    
                            self.bmp = None
                            self.customUiBmp = None
                    
                        def __del__(self):
                            self.thread.End()
                    
                        # Define our Layout
                        def CreateLayout(self):
                            w = c4d.gui.SizePix(100)
                            h = c4d.gui.SizePix(100)
                    
                            bcBitmapButton = c4d.BaseContainer()
                            bcBitmapButton[c4d.BITMAPBUTTON_BUTTON] = True
                            bcBitmapButton[c4d.BITMAPBUTTON_BORDER] = c4d.BORDER_IN
                    
                            self.customUiBmp = self.AddCustomGui(1000, c4d.CUSTOMGUI_BITMAPBUTTON, "", c4d.BFH_FIT | c4d.BFV_TOP, w, h,
                                                                 bcBitmapButton)
                            return True
                    
                        def UpdatePicture(self, bmp):
                            # Called from the thread
                            self.bmp = bmp
                    
                            # Sanity checks if the dialog is opened or eitehr the customUI is not defined
                            if self.IsOpen() and self.customUiBmp is not None:
                    
                                self.customUiBmp.SetImage(self.bmp)
                                if c4d.threading.GeIsMainThread():
                                    self.customUiBmp.Redraw()
                                else:
                                    # If we are not on the main thread, redraw is not allowed, so add a special event with a unique ID
                                    c4d.SpecialEventAdd(PLUGIN_ID_COMMAND_DATA, 0, 0)
                            return True
                    
                        def CoreMessage(self, id, msg):
                            if id == PLUGIN_ID_COMMAND_DATA:
                                self.customUiBmp.Redraw()
                            return True
                    
                    
                    # The CommandData plugin which host the Dialog object alive
                    class CommandDataDlg(c4d.plugins.CommandData):
                        dialog = None
                    
                        def Execute(self, doc):
                            if self.dialog is None:
                                self.dialog = DialogWithBitmap()
                            return self.dialog.Open(dlgtype=c4d.DLG_TYPE_ASYNC, pluginid=PLUGIN_ID_COMMAND_DATA, xpos=-1, ypos=-1,
                                                    defaultw=200, defaulth=150)
                    
                        def RestoreLayout(self, sec_ref):
                            if self.dialog is None:
                                self.dialog = DialogWithBitmap()
                            return self.dialog.Restore(pluginid=PLUGIN_ID_COMMAND_DATA, secret=sec_ref)
                    
                    
                    # Main function
                    def main():
                        c4d.plugins.RegisterCommandPlugin(PLUGIN_ID_COMMAND_DATA, "GeDialog Example", 0, None, "GeDialog Example",
                                                          CommandDataDlg())
                    
                    
                    # Execute main()
                    if __name__ == '__main__':
                        main()
                    

                    Regarding async, I can only forward you to Async IO in Python: A Complete Walkthrough. The main idea is Python does not support MultiThreading, this is the nature of the GIL so only one instruction can be executed in the Python VM machine at a given time. So as an example I write to a file a very very long string of few Gb, The python call is pretty short, what takes the most time is the write into the file (hardware limitation) so instead to wait until the file is written with async stuff you tell, to the python VM it can execute some stuff during this lost time of waiting for hardware (this is a very rough explanation). However, note this is not well supported in Python2.7 but this is in Python3.

                    Cheers,
                    Maxime.

                    MAXON SDK Specialist

                    Development Blog, MAXON Registered Developer

                    1 Reply Last reply Reply Quote 3
                    • lasselauchL
                      lasselauch
                      last edited by m_adam

                      Whoooooooooooop, whoooooooooooop!

                      Thank you so much, @m_adam !!!

                      1 Reply Last reply Reply Quote 0
                      • M
                        m_adam
                        last edited by

                        Since this topic is older than a week I marked is as closed, but feel free to reopen it if you have further questions.

                        Cheers,
                        Maxime

                        MAXON SDK Specialist

                        Development Blog, MAXON Registered Developer

                        1 Reply Last reply Reply Quote 0
                        • B bentraje referenced this topic on
                        • First post
                          Last post