> My suspicion is that this is related to a growing number of files held open 
> by the underlying ImageCache, which will not be immediately closed or free 
> just because you clear() or even destroy the ImageBuf. Or possibly by the 
> overhead of what happens when the maximum number of open files is reached?

I was coming to a similar conclusion when I was trying to modify files in my 
test bed, and the OS was complaining that I still had open filehandles.

> The default is 100, I'm curious what happens if you just raise that. On 
> Linux/OSX it should be safe to go into thousands, but Windows usually has 
> some lower limit, to let's try 500 just to see what happens to your timings. 
> In particular, does the slowdown seem to come later, i.e. after more files 
> have been touched?

I ran some more tests locally and, unfortunately,  I actually didn't see any 
improvement using the cache. Nor do I see much improvement using the invalidate 
method you described.

I've attached a script and some graphs if you wanted to take a look. The only 
real requirement is that you populate a local directory with the same image 
2500x (if you can't get the attachments through here, let me know and I'll 
email them direct).

The interesting bit, is that I always get a linear-ish increase in time with 
the imagebuf, but if I graph the time it takes to open an ImageInput and query 
the spec, its pretty constant.

Curious to know if you have any other thoughts! Thanks again!
-J 


Attachment: oiiotest_imgbuf_perf.py
Description: oiiotest_imgbuf_perf.py

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