I'm a new member of this site. I am making a game where I need to use a lot event listeners.
Problem:
There'll be around 300 event listeners in my game, I'm worried about if this will affect my game?
Yes it will affect your game, primarily because you will need to control all 300 so that they won't create memory leaks in form of defunct (released) objects left in memory because they have a listener attached to say stage. Secondary aspect is performance, each listener taking actions is several function calls below the curtains, thus it's better to organize those listeners somehow. It's fine to have a button listen on itself for say MouseEvent.CLICK and to have 300 buttons like that, because each time you click only a few (ideally one) listeners would react. It's not as fine to have 300 listeners listen for Event.ENTER_FRAME because each frame all of them would be invoked, and it's better to have one listener instead, but every subsystem or every object would then get called from that listener. This approach will also lessen the overhead on Flash event subsystem to direct calls, and lessen your hassle about unattached listeners.
There may be more performance aspects regarding listeners, especially since Flash engine developers started placing security checks into the engine, slowing event processing by a significant margin, these are however obscure and the only thing is known about them is "use fewer listeners". You will still have to rely on Flash event cycle at least on the top level, even if you devise an event processing system of your own, or use a system made by another, but the main point stands, "the fewer, the better". If you can lessen the number of listeners, please do so.
Well you are very vague on the kind of event listeners you use if they are enterframes it could be a issue try not using enterframs on objects and use them on the stage but if you are using 300.
I'm sure only a subset would be Enter_Frames and most will be mouse events. And i don't think most of them would be on active MovieClips.
So only a subset would be active at a time so mostly nothing to be worried about as long as there isn't any unwanted behaviour. I feel you should be good to go . But do Manage all of your enterframes.
Related
I have encountered the following issue. I have an interactive Swing application. It basically creates a bunch of graphical objects on a canvas. You pick the kind you want to create from a palette (oval, circle, etc.) and click on the canvas. Everything works as expected. Now I want to record a test using Abbot/Costello testing framework. It is pretty simple. Fire up Costello app, create a new script and start recording events. Let's say I want to record this sequence: click on a palette and drop a graphic on canvas. It is natural to expect that testing app would record a click before the canvas component had a chance to process it and added a new graphic. For various reasons I need to capture the app's state before any changes are made to it, not after. It turns out that my app gets first crack at the click event resulting in creation of a new graphic and only after that my testing app receives the event for recording. At this point it is too late for me, the state has been irretrievably changed and I am basically recording a future state and not the state that preceded it.
I understand that this is a result of listeners firing in different order. I also understand that Swing makes no guarantees as to the order of firing listeners. Have I reached limits of possible or there is a solution?
As far as I've read in the manuals, when you have to play a sound, you need a Sound object, and make a temporary SoundChannel object that will control the actual playback. I want to know if there is a memory-efficient way of managing those SoundChannel objects. So far it seems that these are of "fire-and-forget" type of objects, and the only way to make them semi-persistent is make the call to Sound.play() with a really great number of plays. But this approach will not work for one-time sounds, like an arrow shot or a button click, for example. And if I call SoundChannel.stop() I can as well discard the object as there is no means to make it resume playing. Is there any solution to not to spawn SoundChannel objects like crazy, and to be able to handle both one-time sound plays and infinite-time sounds aka background music?
SoundChannel is indeed meant to be throw-away, and this kind of heap usage comes with the territory of using a language like ActionScript.
You shouldn't worry about GC usage from sounds - premature optimization is evil! The best you can do is just reuse your Sound object instead of creating a new one each play. There shouldn't be much of a GC issue if you are playing a reasonable number of sounds per frame, say, in a game. SoundChannels are lightweight and reference a single copy of the audio data, so they aren't such a big deal. There will probably be much heavier allocations to worry about, such as game objects or bitmaps.
You could avoid using SoundChannel by dynamically mixing the audio using SampleDataEvent, but this will certainly have the opposite effect and be much more processor-intensive, not to mention more difficult to code.
If you are really worried about the GC, you could use System.pauseForGCIfCollectionImminent method to hint the GC to run during a non-intrusive time, such as during a transition in a game.
I'm new to Actionscript. There's probably a better way to do this, and if there is, I'm all ears.
What I'm trying to do is have a background layer run for, say 150 seconds in a loop. Then have another layer (we'll call it Layer 1) with a single object on it loop for 50 seconds. Is there a way to have Layer 1 loop 3 times inside of that 150 seconds that the background layer is looping?
Here's the reason I want Layer 1 to be shorter:
When a certain combination is entered (for example, A1), an item will pop out of and in front of the object on Layer 1.
I haven't written any code for it yet, but my hopeful plan is to have the background layer run continuously then have different scene sections on Layer 1 for each of the items coming out of the object on Layer 1. That way when A1 is entered, Layer1 can goToAndPlay(51) without messing up the background layer.
If it helps you understand it at all, it's a vending machine project. My group's vending machine is the TARDIS. The TARDIS is flying through space while you're entering what you want out of the vending machine and stuff is popping out of it.
If I understand correctly, the background is a MovieClip that loops within its own timeline. When Flash plays through a timeline, the timing is dependent on the performance of the computer and how complex the animation is. You can add an audio track set to 'streaming' to lock the timing down, which will then drop frames if the CPU is overloaded. I have used a silent sound set to loop infinitely and play mode 'streaming' to do this when there is no audio to be used.
Instead of using timeline animations I would recommend using TweenMax http://www.greensock.com/tweenmax/ as it allows tween chaining, that is creating a chain of sequential and parallel tweens. When you use a tween you define the timing in seconds and can use values like 1.25 seconds. It will be accurate to the timing you define. You can also run methods on complete, use easing and all sorts of goodies. If you get comfortable using this you will be able to create much more complex interactions in your Flash projects and also be able to change animations and timing much easier than messing with the timeline.
In fact when hiring Flash developers we always screen candidates by asking if they prefer to do animations on the timeline or programmatically. Although Flash is on its way out, still good to learn as the ideas will apply to javascript and whatever new technology comes about.
I am a student of Computer Science and have learned many of the basic concepts of what is going on "under the hood" while a computer program is running. But recently I realized that I do not understand how software events work efficiently.
In hardware, this is easy: instead of the processor "busy waiting" to see if something happened, the component sends an interrupt request.
But how does this work in, for example, a mouse-over event? My guess is as follows: if the mouse sends a signal ("moved"), the operating system calculates its new position p, then checks what program is being drawn on the screen, tells that program position p, then the program itself checks what object is at p, checks if any event handlers are associated with said object and finally fires them.
That sounds terribly inefficient to me, since a tiny mouse movement equates to a lot of cpu context switches (which I learned are relatively expensive). And then there are dozens of background applications that may want to do stuff of their own as well.
Where is my intuition failing me? I realize that even "slow" 500MHz processors do 500 million operations per second, but still it seems too much work for such a simple event.
Thanks in advance!
Think of events like network packets, since they're usually handled by similar mechanisms. Now think, your mouse sends a couple of hundred packets a second, maximum, and they're around 6 bytes each. That's nothing compared to the bandwidth capabilities of modern machines.
In fact, you could make a responsive GUI where every mouse motion literally sent a network packet (86 bytes including headers) on hardware built around 20 years ago: X11, the fundamental GUI mechanism for Linux and most other Unixes, can do exactly that, and frequently was used that way in the late 80s and early 90s. When I first used a GUI, that's what it was, and while it wasn't great by current standards, given that it was running on 20 MHz machines, it really was usable.
My understanding is as follows:
Every application/window has an event loop which is filled by the OS-interrupts.
The mouse move will come in there.
All windows have a separate queue/process by my knowledge (in windows since 3.1)
Every window has controls.
The window will bubble up this events to the controls.
The control will determine if the event is for him.
So its not necessary to "compute" which item is drawn under the mouse cursor.
The window, and then the control will determine if the event is for them.
By what criteria do you determine that it's too much? It's as much work as it needs to be. Mouse events happen in the millisecond range. The work required to get it to the handler code is probably measured in microseconds. It's just not an issue.
You're pretty much right - though mouse events occur at a fixed rate(e.g. an USB mouse on linux gives you events 125 times a second by default - which really is not a lot),, and the OS or application might further merge mouse events that's close in time or position before sending it off to be handled
I'm building a remote presentation tool in AS3. In a nutshell, one user (the presenter) has access to a "table of contents" HTML page with links for each slide in the presentation, and an arbitrary number of viewers can watch the presentation on another page, which in turn is in the form of a SWF that polls the server every second to ensure that it's on the right slide. Whenever the admin clicks a slide link in the TOC, the database gets updated, and on its next request the presentation swf compares the label of the slide it's currently displaying to the response it got from the server. If the response differs from the current label, the swf scrubs through the timeline until it finds the right frame label; otherwise, it does nothing and waits for the next poll result (a second later).
Each slide consists of a movieclip with its own nested timeline that loops as long as the slide is displayed. There's no actionscript controlling any of the nested movieclips, nor is there any actionscript on the main timeline except the stop();s on each keyframe (each of which is a slide in the presentation).
Everything is built and working perfectly. The only thing that's troubling is that if the presentation swf is open for long enough (say, 20 minutes), the polling starts to have a noticeable effect on the framerate of the movieclips animating on any given slide. That is, every second, there's a noticeable drop in the framerate of the animations that lasts about three-tenths of a second, which is quite noticeable (and hence is a deal-breaker for the whole presentation suite!).
I know that AS3 has issues with memory management, and I've tried to be diligent in my re-use of objects and event listeners. The code itself is dead simple; there's a Timer instance that fires every second, which triggers a new URLRequest to be loaded by a URLLoader. The URLLoader is reused from call to call, while the URLRequest is not (it needs to be initialized with a new cache-killing value each time, retrieved from a call to new Date().time). The only objects instantiated in the entire class are the Timer, the URLLoader, the various URLRequests (which should be garbage-collected), and the only event listeners are on the Timer (added once), the URLLoader (added once), and on the routines that scrub backwards and forwards in the timeline to find the right slide (and they're removed once the correct slide is found).
I've been using mr doob's stats package to monitor memory usage, which definitely grows over time, so there's gotta be a leak somewhere (it grows from ~30 MB initially to > 200 MB after some scrubbing and about 25 minutes of uptime).
Does anyone have any ideas as to what might be causing the performance problems?
UPDATE: I'm not entirely sure the performance troubles are tied directly to memory; I ran an instance of the presentation swf for about 15 minutes and although memory usage only climbed to around 70 MB (and stayed there), a noticeable hiccup started appearing at one-second intervals, coinciding with the polling calls (tracked via Firebug's Net panel). What else might cause stuttering movieclips?
I know this is coming a bit late, but I have been using Flash Builder's profiler frequently and one thing I found is that the TimerEvent generated by the timer class
uses up quite a bit of memory individually and
seems to not get released properly during garbage collection (even if you stopped the timer and removed all references to it).
A new event is generated for each Timer tick. I use setInterval instead, even though a few AS3 evangelists seem to recommend against that. I don't know why. setInterval still generates timer events, but they appear to be garbage-collected properly over time.
So one strategy may be that
you replace the Timer with a call to setInterval() ... which is arguably more robust code anyway and
(CAUTION) force garbage collection on each slide scrub (but not on each poll). See this question for more details on the pros and cons.
The second suggestion is only a stop-gap measure. I really encourage you to use the profiling tools to find the leak. Flash Builder Pro has a 60-day trial that might help.
Finally, when moving to a completely new slide SWF (not a new timeline position in the current slide), how are you making sure that the previous slide SWF got unloaded properly? Or am I misunderstanding your setup and there is only one actual slide SWF?
Just two things that came into my mind:
Depending on the version of the Flash player and the cpu usage the garbage collections sometimes does not start before 250 MB (or even more) memory are consumed.
Moviesclips, Sprites, Loader and whatever that has an Eventlistener listening will not be killed by the garbage collection.
So I believe your problem is, that either the slides or the loader are not cleaned correctly after you used them, so the were keept in memory.
A good point to start reading: http://www.gskinner.com/blog/archives/2006/06/as3_resource_ma.html