CS3 Multiprocessor rendering problems

[Michael Linde]

I would like a bit of follow up with this. Are the MP crashes resolved with AE 8.0.2 (CS3), and the 8-core issues resolved by manually editing the prefs file to only use 4 cores (both documented on Adobe’s website)?

We are trying to determine if it’s worth upgrading the RAM in our Mac Pro systems from 4 to 12 or 16GB, specifically to set up multiprocessing. Here’s my logic, but I would like to know if anyone has it working in the real world already:

Although CS3 (and CS4) are not 64-bit, and cannot address above 3GB of RAM for the application itself, Adobe has done a few things that suggest a large amount of RAM is accessible to After Effects at different times.

Consider the RAM Cache setting. Since Adobe recommends keeping that at (or below) 60% of available RAM, in a system with 4GB, that means 2.4G is available for the RAM Cache. Tweaking this number to get as close to 3GB would maximize the RAM available to the application, so we’ll keep that in mind.

Next, consider multicore rendering. Mac Pro systems have 4 or 8 cores. Adobe recommends not going over 4 cores, and allocating 2GB per processor (core) for rendering when enabling multiprocessor render. This is a baseline of 8GB for rendering.

With those two things in mind, let’s start the math.

RAM totals
12GB Configuration:
8GB for Rendering
3GB for AE (25% RAM Cache setting) – leaves 1GB for the rest of the system

16GB Configuration
8GB for Rendering
3 GB for AE (18% RAM Cache setting) – leaves 5GB for the rest of the system

In conclusion, although AE itself cannot access more than that 3GB cap, by enabling multiprocessing (set to a maximum of 4 cores) and installing 12-16GB of RAM, you can have maximum performance out of AE in both production and rendering.

And that’s the argument for RAM

[David Chaudoir]

My Quad core renders fine with Multiprocessor switched on and in some instances more than halves the render time. However in order to work on the project I switch the Multiprocessor off – otherwise I suffer from diabolical time delays waiting for the damn thing to preview.

[Bryce Duncan]

I have experienced this using multiprocessor rendering in CS3–but when accessing source material on a network drive over ethernet. In my opinion, the multiple processes have trouble accessing the source material and then ‘time out.’ They render the footage as if it was missing and move on to the next frame. (This doesn’t seem to be an issue using one processor to render over the network.)

The error is also random because depending on how many processes you have running, the error could be generated by any one of them and that bad frame will be added to the finished render as soon as it is complete.

[Touko Maksimainen]

I’m in the same boat with you guys. I’ve got 8Gb RAM with a Quad-core setup. I get about half a dozen crashes on any given day. Most of the time everything works fine if I just leave the computer alone, but as soon as I touch anything AE will freeze. Needless to say this wastes huge amounts of my time.

The issues how I understand it is with how AE renders comps, caching (render into RAM) every layer individually and then stacking them up to make up the final render.

Now, the problem inherent in this approach is that it requires lots and lots of random access memory. As AE is still a 32-bit piece of software it has significant limitations on how much memory it can use. Adobe is circumventing this problem by spawning multiple instances of the application, each able to see 3GB.

So there can be up to 8 cores requesting their slice of the memory, which not many people have 3 times the number of cores, compounded by the fact that the OS needs 1-2 gigabytes on top of that.

So if, or rather when, the AE spawlings have insufficient RAM to fight over, AE can’t recognize or handle the situation properly (like dropping cores or start swapping to hard disk) and simply collapses on itself.

Hence the Adobe recommendation for not using the full 8 cores.