Hello all, This post is a follow-up to the previous one from Frank and memory management issues.
Some of you may have noticed the 'MMGT_OPT' env variable that is set up after OpenCASCADE6.3.0 installation. According to the documentation, setting this flag to '1' tells OpenCASCADE to use a Memory ManaGemenT OPTimizer. Information about this flag can be read from the official OCC documentation or from the OCC forum. It appears this optimizer is actually a speed optimizer for memory freeing. Instead of a theoretical explanation (that I'm incapable of), here are the results from a simple test script (see document attached). This script simply: - calls the creation of 10.000 elementary boxes, - displays the memory consumed - delete objects and display the time required for this operation, - display the memory consumed after objects are deleted. * tests condition: Test machine: MacBookPro - 2.53GHz Intel Core 2 Duo - 4Go DDR3 Test OS: MacOSX 10.6 (Snow Leopard) pythonOCC svn rev. 924 * First test: run test_mmgt_opt.py script with MMGT_OPT enabled: The output is: macbook-pro-de-thomas-paviot:unittest thomas$ export MMGT_OPT=1 macbook-pro-de-thomas-paviot:unittest thomas$ python test_mmgt_opt.py Creating 10000 boxes... done. Consumed memory: 156.011719 Mb before deleting objects deleting objects... done in 0.208458s. Consumed memory: 156.027344 Mb after deleting objects macbook-pro-de-thomas-paviot:unittest thomas$ This test shows that OpenCASCADE doesn't free the memory after the memory is deleted. OCC manages memory blocks in a smart way to speed up. * Second test: run test_mmgt_opt.py script when MMGT_OPT disabled The output is: macbook-pro-de-thomas-paviot:unittest thomas$ export MMGT_OPT=0 macbook-pro-de-thomas-paviot:unittest thomas$ python test_mmgt_opt.py Creating 10000 boxes... done. Consumed memory: 148.441406 Mb before deleting objects deleting objects... done in 0.484035s. Consumed memory: 19.460938 Mb after deleting objects macbook-pro-de-thomas-paviot:unittest thomas$ 2 interesting results: - at first, we can see that the memory is freed immediately after the objects are deleted, - the time required to delete the objects is about 2X more important compared to the first test (I ran each test about 10 times to check that this time is constant). Conclusion: ======== If your function/method/app requires speed, enable MMGT_OPT. Otherwise, it's better to disable it. Best Regards, Thomas
test_mmgt_opt.py
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