>>>>> "DL" == Donald Leslie {74279} <[EMAIL PROTECTED]> writes:DL> I have an apache/mod-perl application that can results in large DL> xml strings which are then transformed by xslt into html. A DL> database query can result in an xml string with a length greater DL> than 300,000 . In a normal perl allocation you can pre-extend the DL> string to prevent repeated new allocations and copies. Does anyone DL> know what happens in a mod-perl application? Does pre-extending DL> have any benefit? i can't tell you about any mod-perl issues but in general pre-extending in perl doesn't gain you as much as you would think. the reason is that some storage isn't really truely freed to the main pool when it gets freed when its ref count goes to 0. perl will keep it around in anticipation of it be reallocated for this same item in a future call or loop iteration. so it is effectively doing the usual doubling its size to grow into the first large string and then it is already prextended the rest of the time via reusing the previous buffer. of course this could be totally wrong as i am not nuts enough to get into perl's guts but that is what i have understood to happen. this is can be benchmarked by comparing the first time something is allocated with doubling vs a preextend. you have to be careful to factor out the virtual ram allocation. one idea would be to preallocate and free a larger chunk before you run the benchmark so that virtual ram will likely be cached in real ram. and on a final note, these days 300k is not even a long string. uri -- Uri Guttman ------ [EMAIL PROTECTED] -------- http://www.stemsystems.com --Perl Consulting, Stem Development, Systems Architecture, Design and Coding- Search or Offer Perl Jobs ---------------------------- http://jobs.perl.org _______________________________________________ Boston-pm mailing list [email protected] http://mail.pm.org/mailman/listinfo/boston-pm
