Hello! I merged `master' in the `boehm-demers-weiser-gc' branch yesterday, which hadn't been done since before 1.9.0 (no, you won't see the 4 MiB+ commit message on `guile-commits'...).
So now is a good time to test it and report back! It requires libgc 7.1 or later, which isn't packaged in Debian, although it was released in May 2008. I'll post updated comparative benchmarks hopefully in the next few days. I hope we can merge it by the time 2.0 is released, which leaves us with just a couple of months (in theory, at least). Thus I encourage people enthusiastic about it to try it and report back. Otherwise we'll have to wait for Guile 3.0, which is due in 2017 Q4. You've been warned. :-) Thanks, Ludo'.
