On 10/13/2016 08:16 AM, Janne Blomqvist wrote:
Currently GFortran newer reuses unit numbers allocated with NEWUNIT=, instead having a simple counter that is decremented each time such a unit is opened. For a long running program which repeatedly opens files with NEWUNIT= and closes them, the counter can wrap around and cause an abort. This patch replaces the counter with an allocator that keeps track of which units numbers are allocated, and can reuse them once they have been deallocated. Since operating systems tend to limit the number of simultaneous open files for a process to a relatively modest number, a relatively simple approach with a linear scan through an array suffices. Though as a small optimization there is a low water indicator keeping track of the index for which all unit numbers below are already allocated. This linear scan also ensures that we always allocate the smallest available unit number.2016-10-13 Janne Blomqvist <j...@gcc.gnu.org> PR libfortran/48587 * io/io.h (get_unique_unit_number): Remove prototype. (newunit_alloc): New prototype. * io/open.c (st_open): Call newunit_alloc. * io/unit.c (newunits,newunit_size,newunit_lwi): New static variables. (GFC_FIRST_NEWUNIT): Rename to NEWUNIT_START. (next_available_newunit): Remove variable. (get_unit): Call newunit_alloc. (close_unit_1): Call newunit_free. (close_units): Free newunits array. (get_unique_number): Remove function. (newunit_alloc): New function. (newunit_free): New function. Regtested on x86_64-pc-linux-gnu. Ok for trunk?
Yes, OK, clever! Thanks! Jerry
