topic Allocate with STAT of a very large array on Mac outputs an inte in Intel® Fortran Compiler

Allocate with STAT of a very large array on Mac outputs an internal error message with -i8

Cross__Mat — Wed, 07 Mar 2012 10:54:50 GMT

$ uname -a
Darwin lion.nag.co.uk 11.2.0 Darwin Kernel Version 11.2.0: Tue Aug 9 20:54:00 PDT 2011; root:xnu-1699.24.8~1/RELEASE_X86_64 x86_64

$ ifort -V
Intel Fortran Intel 64 Compiler XE for applications running on Intel 64, Version 12.1.1.246 Build 20111011

$ cat big_alloc.f90
real, Allocatable :: x(:,:)
integer d, m, alloc_stat
d = int(1.6*huge(1)**0.25)
m = (d+1)*(d+2)/2 + 2
Allocate (x(d,m),Stat=alloc_stat)
end

$ ifort -i8 big_alloc.f90 ; ./a.out
a.out(81731) malloc: *** mmap(size=1371091381248000) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug

alloc_stat is correctly set as /= 0, so this is just a bit unsightly really.

It doesn't seem to happen on Linux.

I'm not really a Mac user, so I'm not sure what other info to send that would be helpful!

Allocate with STAT of a very large array on Mac outputs an inte

mecej4 — Wed, 07 Mar 2012 11:01:15 GMT

I am not a Mac user, either, so this is just a guess: the message is probably from the underlying C library rather than from the Intel Fortran runtime. Sometimes there is an environmental variable that can be set to control messages from MALLOC and even to control subsequent action.

Allocate with STAT of a very large array on Mac outputs an inte

jimdempseyatthecove — Wed, 07 Mar 2012 15:52:28 GMT

Mat,

The problem is:

with default integer(4) huge(1) == 2147483647
d becomes 344, n becomes 59687
x(344,59687) * 4 = 82,129,312 bytes

with default integer(8) huge(1) ==9223372036854775807
d becomes 88174, n becomes 3887459402
x(88174,3887459402) * 4 =1,371,091,381,247,792 bytes

Jim Dempsey

Allocate with STAT of a very large array on Mac outputs an inte

mecej4 — Wed, 07 Mar 2012 16:07:00 GMT

Jim, your estimate is

x(88174,3887459402) * 4 =1,371,091,381,247,792 bytes

which, when rounded up, matches the value in the MALLOC error message,

mmap(size=1371091381248000) failed (error code=12)

This is about 1.4 petabytes.

Allocate with STAT of a very large array on Mac outputs an inte

Cross__Mat — Wed, 07 Mar 2012 16:59:41 GMT

It's unfortunate though that it gets exposed like this. Wouldn't you expect the compiler to trap and control the subsequent action itself?

Allocate with STAT of a very large array on Mac outputs an inte

Cross__Mat — Wed, 07 Mar 2012 17:03:59 GMT

Thanks. I'm expecting the allocation to fail. The problem is that there's a nasty error message bubbling up from the guts of _somewhere_.

Allocate with STAT of a very large array on Mac outputs an inte

jimdempseyatthecove — Wed, 07 Mar 2012 20:46:24 GMT

>>The problem is that there's a nasty error message bubbling up from the guts of _somewhere_.

It is bubling up from the C Runtime Library in the malloc function.

This is not an Intel Visual Fortran issue. It is an issue with the C Runtime Library as it interfaces with the O/S. In your case this is the MAC O/S. Consult with/on the MAC forums relating to too large of allocations causing error trap as opposed to returning NULL.

Jim Dempsey