[Bug libfortran/35063] [Regression wrt g77] I/O leaks handles/memory on Windows XP

[jvdelisle at gcc dot gnu dot org]

------- Comment #25 from jvdelisle at gcc dot gnu dot org  2008-02-08 14:26 -------
Reply to comment #23.  With external units we have a treap structure which
holds pointers to the unit structures so that we reuse them as needed  The
treap is searched first for an existing unit and returns that if it exists. 
This keys off of the unit number.  This one handle per unit.

With internal units we do not have a unit number to key off.  I could use the
address of the string itself. I have not pursued that avebue yet because it is
not the simplest approach.

I have successfully tested a patch that uses a single static unit structure for
all internal units, relying on the locking mechanism to assure that it is used
only by one operation at a time.  It works great and improves performance by
avoiding the memory allocation overhead. It uses at most only one handle.
Unfortunately, it breaks write_recursive.f90.  Recursive I/O is permitted on
internal units in F2003.

Reply to comment #24
The patch from Danny adds a new function to gthr-win32.c that does a
CloseHandle.  I will be testing this approach soon.

Regardless, I am leaning toward not locking the internal units because of some
performance gain and the need to retain recursive IO.  I will do some
comparative tests between the CloseHandle approach and the no lock approach
before proposing to the list the final patch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35063