ThreadRequest : yet another plugin for multithread processing

[Gavino]

Originally Posted by CruNcher

Interesting it seem combining SetMtMode(2) + .ThreadRequest for only the heaviest parts (tried with filter like yadif and unblock) seems to be faster then to use .ThreadRequest in every line alone
for example this was more efficient

SetMTMode(2)
directshowsource("E:\test.ts", audio=false)
Yadif(mode=0,order=1).ThreadRequest()
...

Be careful about drawing general conclusions from a very simple script. It's no surprise that SetMTMode will give almost 100% CPU usage here, since by default it creates a thread for each processor and the script has a simple temporal behaviour. I suspect you would see similar performance with just SetMTMode alone, without ThreadRequest. Did you try that?

On a separate but related note, I have some thoughts on the relative usefulness of ThreadRequest v SetMTMode, based on the different ways they work...

Each instance of ThreadRequest effectively divides the filter chain (or in the general case, a branch of the filter graph) into two parts - the part above it is run in a different thread, in parallel with the part below, which it feeds in a pipeline-like manner. Therefore, it will be most effective when these two parts are doing equal work; otherwise the slower thread will spend time waiting for the faster one.

Similarly, in a chain of filters and ThreadRequests, each section of the chain should be balanced. Therefore, if you have n processors, you want to divide the filter chain into n parts, each of which takes roughly the same amount of time, and apply ThreadRequest to each part. Simply adding ThreadRequest on each line is unlikely to be the optimum strategy.

By contrast, both SetMTMode and MT() automatically provide this 'load balancing' as they divide the frames either temporally (SetMTMode) or spatially (MT) to give equal work to each thread. This makes them IMHO much simpler to use effectively.

[Frank K Abbott]

What is the correct usage of threadrequest in order to have some assurance that it won't crash on the 2000'th or 3000'th frame?

[dansrfe]

Ok so I tried running this in my script on a few lines and I get peculiar results.

Total frames: 210,439

~120,000 the script runes at 2x then without ThreadRequest()

after ~120,000 frames the script starts running at 1/3 fps then the normal script and it becomes unbearablly slow with the same amount of cpu usage and memory usage.

I have a feeling this might have to do with me not using synchronize mainly because I don't know how to use it effectively I guess.

[dansrfe]

Can some kind and generous person please look at the source code for this plugin and explain how it works and possibly improve it? This plugin EXTREMELY increases my on-the-fly ffdshow/AviSynth speed with filters that usually just barely make the cut on my cpu an stutter a little bit. I really, truly think this filter has some potential and it runs fairly stable with certain types of filters on-the-fly and possibly for encoding.

[Overdrive80]

Do you get this filter more efficiency than MT????

[Sparktank]

Since the original link(s) don't work, and the site is down, and I can't really find an archive of the site, I uploaded the original (last version) with the source included.

original + source
http://www.mediafire.com/download/4x...quest_102a.rar

In case anyone wants to take a stab at updating (for anything) or just for archival purposes.

[Reel.Deel]

Thanks Sparktank. Archive.org has the author's page archived but not the downloads.

https://web.archive.org/web/20130124...avisynth.shtml