As I already mentioned, I have been developing an ACIS translator for CAD Exchanger designing its architecture for multi-core from the very beginning. Today I performed a series of performance tests of its Alpha version executing multiple-files (from 150Kb to 55Mb) on different hardware (2/4/8 cores). The same set of tests have been executed against another ACIS translator and I am proud to state that mine has fully outperformed it ! The lowest gain was about 15% on a smaller file and the highest gain was 10x on the biggest one (it took CAD Exchanger ACIS translator only 23 seconds while the competitor needed 230seconds to translate a model of 55Mb). Obviously the latter gain will be most noticeable for the user.

I made some video running a live test of one model to demonstrate parallelism on an Intel Core i7 workstation. Sorry for sound artifacts – I was simply using my laptop for video recording, so you may notice hard disk crunching :-(.



There are several phases in the ACIS translator – parsing a file, creating a transient file model in memory, converting it into Open CASCADE shape, and eventually shape analysis and correction. Conversion and correction which take the largest share of time are fully concurrent and scale very well in most cases. Parsing a file is obviously a single-threaded task. And a phase of creating a transient model, even though architecture allows to make it fully parallel I had to execute sequentially being a hostage of Microsoft STL bug mentioned in an earlier post. With growing number of cores this phase becomes considerable comparing to others thus making the whole translation worse scalable. Hope that Microsoft will fix it earlier than I decide to implement own string parsing ;-).

The code takes advantage of Intel Threading Building Blocks which I loved for its ease of use, excellent scalability and very low overhead (I did not notice much difference running TBB with only one thread vs simple sequential execution). There are also a couple of know-how architectural algorithms that made this concurrency possible, which I am quite proud of;-).

Development of the ACIS translator will continue and should make it into the CAD Exchanger GUI eventually. It will also be offered as a C++ software library that you could use in your Open CASCADE-based application to read ACIS-SAT files. By the way, I was impressed to find hundreds of ACIS files all over the internet which really underlines its popularity.
If you would like to evaluate it please let me know.

Thanks !