fortran test memory overflow

Question

I am running a FORTRAN program that allocates memory dynamically for rather large arrays, and sometimes they do not fit into memory.

Thus the allocation

 allocate(my_array(really big_number))

will give the error

Operating system error: Cannot allocate memory
Allocation would exceed memory limit

and the program would exit. I would like to know if there is any way to capture this or test that the memory will be available, so that i can take appropriate measures if I'm not allowed to allocate such a big array?

Michael Burr · Accepted Answer · 2014-10-26 09:28:20Z

1

Use: allocate(my_array(really big_number),stat=ierror)

With the stat= specifier, the status of the allocation will be stored in the specified variable (ierror in the example). Zero means the allocation succeeded, non-zero means it failed.

From the Fortran 90 standard (ftp://ftp.nag.co.uk/sc22wg5/N001-N1100/N692.pdf) on the ALLOCATE statement:

If the STAT= specifier is present, successful execution of the ALLOCATE statement causes the stat-variable to become defined with a value of zero.

If an error condition occurs during the execution of the ALLOCATE statement, the stat-variable becomes defined with a processor-dependent positive integer value. If an error condition occurs during execution of an ALLOCATE statement that does not contain the STAT= specifier, execution of the executable program is terminated.

answered Oct 26, 2014 at 9:28

Michael Burr

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1 Comment

Vladimir F Героям слава Over a year ago

Worth to note it is not bomb proof. En error can still be encountered when accessing the array on some systems.

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