RE: [Axiom-developer] Memory leak in Axiom

[Vanuxem Grégory]

Hi,

Le mardi 21 juin 2005 à 21:49 -0400, Page, Bill a écrit : 
> I wrote:
> > ...
> > If you repeat this process several times:
> >
> > 1) Open Axiom
> > 2) Allocate Matrix
> > 3) Close Axiom
> > 4) display residual and virtural memory
> >
> > For example do this 5 times in a row, do you find that the
> > total available memory is constantly decreasing?
> > ...
> >
> > Could you describe the test you use on GCL? What version of
> > gcl are you using?
> 
> On Tuesday, June 21, 2005 9:10 PM Vanuxem Grégory wrote:
> 
> > (make-array '(1000 1000) :element-type 'long-float :initial-element 0)
> >
> > about 50 times
> >
> 
> I GCL I am not certain that this function will necessarily allocate
> all of the memory that might be required if each element of the
> array was explicitly given some value.
> 
> > ...
> > Sorry,
> > 1) Open Axiom
> > 4) display residual and virtural memory
> > -- avoid printing
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > new(1000,1000,0)$Matrix(SF);
> > -- memory has increased of 10Mb
> > .
> > .
> > .
> > a lot of times (axiom will crash) => xmalloc failed
> 
> Why do say that this sort of test represents a "memory leak"?
> If you do not close Axiom between these allocations of memory
> you can not be testing for the conditional called a "memory leak".
> A memory leak is a serious problem that occurs when a process does
> not give back to the operating system some memory that it allocated
> when it closes.

I thought it's a forgotten allocated memory.

example in C language:
a = malloc(x)
do work and never release this memory.

Memory is released when the process exit.


Cheers,

Greg

> 
> It seems quite normal to me that allocating many large arrays
> eventually uses up all available virtual memory. It is possible
> that Axiom is using a different data structure for representing
> a Matrix then the GCL make-array.
> 
> Regards,
> Bill Page.
>