Hi Leslie et al, On Wed, Oct 14, 2009 at 4:37 AM, Leslie P. Polzer <s...@viridian-project.de> wrote: > The attached patch makes BDB more robust against interrupts in various > places. It achieves this mainly by wrapping critical paths in > WITHOUT-INTERRUPTS and by registering cursors on the Lisp level > (and cleaning up any dangling ones when the txn ends).
Why do these sections require WITHOUT-INTERRUPTS instead of locking? WITHOUT-INTERRUPTS is deprecated in Allegro, and in lisps running on multiple cores, it seems to have no atomicity guarantees that are immediately relevant to me. Quoted below is the Allegro documentation. I'm not sure if WITHOUT-INTERRUPTS has the same semantics in other lisps: "Because Symmetric Multiprocessing (SMP) will be introduced into Allegro CL 9.0 on some platforms, use of multiprocessing macros without-interrupts and sys:without-scheduling, whose behavior is significantly different in an SMP environment, is deprecated, particularly for those users who intend to use the SMP facility. See smp.htm for full details, but in brief, without-interrupts and sys:without-scheduling effectively provided object locking -- because they prevented process switches, and only one Lisp process could ever run at a time, no object could be modified by another process while code wrapped in the macros was being run. In an SMP Lisp, that is no longer true because processes can run on separate processors simultaneously. Therefore, object locking must be achieved in some other fashion. See smp.htm for links to object locking functionality." > > This is work in progress, although it passes the test suite. > > Leslie > > -- > http://www.linkedin.com/in/polzer > _______________________________________________ > elephant-devel site list > elephant-devel@common-lisp.net > http://common-lisp.net/mailman/listinfo/elephant-devel > Best, Red Daly _______________________________________________ elephant-devel site list elephant-devel@common-lisp.net http://common-lisp.net/mailman/listinfo/elephant-devel
