Re: [Caml-list] concurrent gc?

["John F. Carr" <jfc@MIT.EDU>]

 > I should have noted that my main concern is with pauses, not with
 > overall speedup. In other words: in interactive apps, pauses are
 > eeeeeevil.
 > 
 > > For technical reasons, offloading major collections in OCaml is easier
 > > than offloading minor collections, so the potential benefit is less.
 > 
 > I am guessing you mean that major collections just don't happen that
 > often, at least if people write their code in a non-pathalogical
 > fashion? :)

OCaml's runtime is designed around the assumption that access to the
minor heap is fast and the minor heap is only emptied when the program
is stopped.  More generally, no object moves except when the program
is stopped.  Every minor collection moves objects, while most major
collections do not.  The runtime can even be told not to move objects
during a major collection.

So minor collections have to happen while the main program is stopped,
or you have a large rather than a small change to the compiler-runtime
interface.

Full major collections are infrequent.  The runtime is designed to do
some amount of major collection work after each minor GC.  For
example, it might mark 10000 objects before restarting the program,
even though there are a million objects in the heap.  It is this
"slice" of work that could be overlapped with execution of the main
program.

Before writing a concurrent garbage collector, try

1. Turn down the amount of work done at each major collection slice.

2. Reduce the size of the minor heap.

See the Gc module and OCAMLRUNPARAM environment variable.