On Fri, Mar 21, 2003 at 02:04:39PM +0100, Michael Van Canneyt wrote: > > > On Fri, 21 Mar 2003, Anton Tichawa wrote: > > > On Friday 21 March 2003 13:09, you wrote: > > > > On Friday 21 March 2003 12:29, you wrote: > > > >> >> > But, when I use fail in my simple example program, it returns > > > >> >> > > > >> >> NIL okay but > > > >> >> > > > >> >> > the Heaptrace function tells me I have two unfreed memory blocks > > > >> > > > >> (36 > > > >> > > > >> >> > bytes). > > > >> >> > I can't see a memory leak anywhere else in that program, what > > > >> >> > > > >> >> could cause > > > >> >> > > > >> >> > this? (Heaptrace output is as follows: I am using FPC 1.0.6 btw) > > > >> >> > > > >> >> [snip heap dump] > > > >> >> > > > >> >> That is the exception frame that is left on the heap. I don't have > > > >> > > > >> the > > > >> > > > >> >> time to analyze what the cause is that the exception frame is not > > > >> >> removed. > > > >> > > > > >> > It may be a bug in 1.0.6 which has subsequently been fixed. I > > > >> > > > >> downloaded > > > >> > > > >> > and > > > >> > installed the 1.1 snapshots and compiled the same source code, and the > > > >> > memory leak vanishes.... > > > >> > > > >> The reason why 1.1 has no leak is that it uses the stack to store the > > > >> exception frames. The real problem is still there, because exception > > > >> stack > > > >> is still not updated > > > > > > > > some months ago i had a discussion with a friend, converning global > > > > (static, > > > > absolute) variables. his point of view was that they're not necessary > > > > when using oop; mine was, sometimes they're absoulutely necessary. > > > > > > > > if we have just one level of exception processing above normal program > > > > execution (i. e. while an exception is being processed, no other > > > > exception will gain control), we can use absolute variables for the > > > > exception frame. > > > > > > > > it's even possible to define a fixed whole number of exception layers and > > > > allocate absolute memory for N exception levels. > > > > > > > > that memory space would not get lost, as it can be saved by allocating > > > > the 'normal' stack or 'normal' heap more tightly - the old system has to > > > > reserve > > > > exception spae implicitely on the stack or on the heap. > > > > > > > > what do you think about that? > > > > > > It does not fix the problem, the frame is then still left on the stack. > > > > > > The allocation on the heap has already been changed to allocation on the > > > stack in 1.1, because hat is much faster. Using a predefined storage of N > > > exception levels is adding a limit and that is something we want to > > > prevent. > > > > but also the power-switch, the data bus width, and the exception vectors in > > ROM now are limits. i think limits cannot be prevented, but they can be > > chosen knowingly, harmonic, and safe or so. every limit should include the > > overhead to overcome it later, as things get better. > > Not in this case. For instance recursive routines will get in trouble. > There is no way to know how deep the stack can be nested, so you cannot > foresee this. Putting a limit on that is out of the question.
Agreed. If you put a limit on that, you will disallow algorithms that use resursive loops. There are many that do ... cheers James > > Michael. > > _______________________________________________ > fpc-pascal maillist - [EMAIL PROTECTED] > http://lists.freepascal.org/mailman/listinfo/fpc-pascal _______________________________________________ fpc-pascal maillist - [EMAIL PROTECTED] http://lists.freepascal.org/mailman/listinfo/fpc-pascal
