multiprocessing error

Hi

I have a annoying problem, I am rendering out a heavy project with multiprocessing. I use a 4 core with 6gb of RAM.

All works fine for an hour or so, then suddenly I see that it only uses one of the cores?? it started with all four of them..

anyone?

/James

are you looking at the processes thru the activity monitor utility (or similar system process viewer for pc) and seeing that the 'aeselflink' processes aren't being used or are inactive? and does it happen in the same point in the comp?

the particle playground effect seems to disable multiprocessing for some reason. i noticed when using the effect, when doing a ram preview that the info panel stated 'incompatible comp, multiprocessing disabled'. so there may be other effects that inhibit ae's multiprocessing. so, i was thinking if the render switches multiprocessing off at the same point, that point may coincide with an effect that is not multiprocessing friendly.

i'm not sure why ae would switch off multiprocessing due to ram use, but if multiprocessing disables at the point that the 'ram usage' value (as seen in the render queue) hits the maximum ram cache setting you have set in the memory and cache settings, then it may be a problem with the ram cache not clearing (although that usually results in a crash). however, if you think that is the case, you can set ae to purge the cache at set intervals in the secret preference (hold the shift key, then select preferences>general, then click the pref pulldown menu and choose 'secret', from there enter a value in frames to force ae to purge the cache, use a value that is less than where the multiprocessing seems to stop).

the hack that dave mentions was posted by adobe as a workaround to a problem with machines with 8 or more cores, but many people use t to limit the number of cores that can be used by ae, allowing them to be used by other applications or the system. it has also been used to try to give each core the optimal 2gb of ram (note, in the one test i did, i didn't see much of a difference). however, if you think this may be your issue, you can read the post here. the basic steps are this:
1. Quit After Effects.
2. Open the After Effects text preferences file, Adobe After Effects 8.0 Prefs.txt, located in the following folder:
Mac OS: Users//Library/Preferences/Adobe/After Effects/8.0
Windows XP: C:Documents and SettingsApplication DataAdobeAfter Effects8.0
Windows Vista: C:UsersAppDataRoamingAdobeAfter Effects8.0
3. Find the ['MP'] section.
4. Change the "MaxNumberOfProcesses" value to "6".
5. Save and close the preferences file.



Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

it's interesting, i haven't noticed or heard of this before.

you can actually do the hack, if you wanted to try it. it was a specific workaround for 8-core machines before the latest cs3 update, but you can set the "MaxNumberOfProcesses" to 2 or 3 to see if it helps. you don't really need to be concerned about messing up the pref file, since ae will make a new one if you simply remove it from the folder (or if you wanted to keep all your current settings, make a copy of it on the desktop so you can replace it later). many people are using this hack to give some processing power to other applications while rendering.

what are some of the other details about your system, like drives and drive arrays/controllers? and what are your disk cache settings? i'm wondering if you have a data bottle neck somewhere. it's recommended that your disk cache be on a separate controller than your media and render destination. so, if you have a separate drive and controller (like and external sata card, or firewire drive) for your media, make sure the disk cache is on a different drive and controller, like the main drive. if you only have one drive, try disabling disk caching and see if that helps.

another potential issue may be the codec... when writing a single media file (like mov or avi), it's my understanding that one core has to do all the encoding. you might try rendering to an image sequence, which should allow each core to write its own frame.... i'm kind of reaching on this one, but it seems plausible.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

I run into this problem frequently. Are you using BCC effects by any chance? I have noticed BCC is involved nearly every time I have encountered this. The other thing I have noticed is that Avid may be running concurrently but not always. I have solved the problem by removing one or both of these factors. I highly suspect BCC is conflicting with another plugin. But I cannot seem to prove it since during tests removing the BCC will correct but removing other effects does not. (Guess that's a sign it isn't the case.) maybe a better scenario is that the BCC AVX plugins are competing for resources. Hope this helps.