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[REBOL] Re: Severe bug with large sizes of 'mold values in Windows 2000 with Reb

From: nitsch-lists::netcologne::de at: 3-Nov-2001 3:46

RE: [REBOL] Severe bug with large sizes of 'mold values in Windows 2000 with Rebol/View Hi Andrew [Al--Bri--xtra--co--nz] wrote:
> I've only just come across this bug and I'm not sure if it's confined to > Windows 2000 and Rebol/View. I had a large block of 699 objects. Each object > could be 'save-d in a text file that is 17 Kbytes in size (I found this out > later on). So the total 'mold-ed value is nearly 12 megabytes in size. > Rebol/View failed in this task (no error message though), and Windows 2000 > popped up with the error message (IIRC): > > Your virtual memory ... is too small. > While this ... is being enlarged, allocations will fail. > > I clicked OK and waited, nothing happened. I checked with the task manager > program and saw that the Rebol.exe process was using nearly 100% processor > time and consuming around 21Megabytes of memory. Then Rebol would release it > all to nearly 14 megabytes and ramp up again to 21, much like a sawtooth > pattern. It did this for around 8 minutes, before I finally stopped Rebol > with the task manager. > > Unfortunately, I haven't got a test program, as my script created these 699 > objects in a block from a 4 megabyte long BASIC data file. > > When I used a 'foreach and 'save-d the objects individually, everything > worked fine (with small objects). When I went back to 'save-ing the block, > the same problem occured. > > I suspect that this problem might occur with any mold value that results in > output greater than 10 - 12 megabytes, but I haven't confirmed it. It may > also be a similar problem to the problem that occurs when trying to 'probe > system from inside Rebol/View. > > I've emailed this to [feedback--rebol--com] as well. > > Anyone got any suggestions? >
looks like a bad increasion scheme. like following: lets say, we have a block/string and this gets to small. so automatic allocates old size + 1000, copies old stuff, changes refence and ok. well, if there is a lot to copy, it will trigger garbage collection. now it depends: if rebol does it right, it will allocate old buffer + 100% or that, based on block size. if it does it wrong, it adds a fixed amount. lets say we have 10000K and rebol increases with 1K, it would have to do 10000 copies of some mb, and a gc each time. that would give this saw-tooth. with 100% it would go to needed size very quick, but waste quarter of memory. i had a similar behavior once when i filled a very large block, unusable. then i checkt size before inserting and reallocated by hand, and it worked. -Volker