[Python-Dev] _sre changes (original) (raw)

Michael Hudson mwh@python.net
Sun, 25 May 2003 17:27:22 +0100

Andrew MacIntyre <andymac@bullseye.apana.org.au> writes:

On Sat, 24 May 2003, Gustavo Niemeyer wrote:

to backport some of the fixes we have introduced in the regular expression engine in 2.3 to 2.2.3, or is it too late? We have a sf patch open about that, but I'd like to port only the changes that don't require major changes in the engine. These sre changes are giving me fits on FreeBSD. The fix (recursion limit down to 7500 for gcc 3.x) applied for 2.3b1 now needs to be extended to gcc 2.95, and the limit for gcc 3.x lowered further - not a particularly satisfactory outcome. I have identified that the problem is not the compiler specifically, but an interaction with FreeBSD's pthreads implementation (libcr) - ./configure --without-threads produces an interpreter which survives testre with a recursion limit of 10000 regardless of compiler.

This is to be expected. If you run a threads disabled Python with ulimit -s you can recurse until you run out of VIRTUAL MEMORY!

When there are threads in the picture is significantly more complex... (which is another way of stating that I don't understand it, but you can understand that with multiple stacks you can't just say "here's a really high address, work down from here"[1]).

Cheers, M.

[1] or vice versa depending on architecture.

-- -Dr. Olin Shivers, Ph.D., Cranberry-Melon School of Cucumber Science -- seen in comp.lang.scheme