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From: Eli Zaretskii <eliz@gnu.org>
To: Pip Cet <pipcet@gmail.com>
Cc: eggert@cs.ucla.edu, emacs-devel@gnu.org
Subject: Re: Changes in GC and in pure space (was: [Emacs-diffs] master 5d4dd55: Fix lifetime error in previous patch)
Date: Tue, 23 Jul 2019 17:56:14 +0300	[thread overview]
Message-ID: <83imrspzox.fsf@gnu.org> (raw)
In-Reply-To: <CAOqdjBez+8BeDzcqZLFWTDCHij8kjyuCU7pXudt0ArGN9Myr-Q@mail.gmail.com> (message from Pip Cet on Mon, 22 Jul 2019 19:05:43 +0000)

> From: Pip Cet <pipcet@gmail.com>
> Date: Mon, 22 Jul 2019 19:05:43 +0000
> Cc: eggert@cs.ucla.edu, emacs-devel@gnu.org
> 
> > The same goes for removing the pure space, IMO: another core feature
> > whose existence and traits many parts of Emacs came to take for
> > granted.
> 
> Let's not remove pure space for Emacs 27.
> 
> (The traits of pure space changed significantly, with the introduction
> of pdumper: CHECK_IMPURE is now a nop rather than a valuable debugging
> aid, and PURE_P is always false. That is something we should mention
> somewhere, along with all the good NEWS, because it will make Emacs 27
> harder to maintain.  But that's all we should do, I think, document
> the odd state we're in now and resolve to change it when it is more
> appropriate to do so.)
> 
> > I'm all for improving GC and simplifying our memory management, but
> > please keep the above in your minds when you play with this stuff.
> > Especially as, judging by the changes you are making, the details and
> > indeed some of the aspects of the idea of the changes, are not yet
> > sufficiently clear/finalized.
> 
> I'm forced to agree, as far as my ideas are concerned.
> 
> Eager rehashing of hash tables: needs to be timed precisely right for
> user-defined dumped hash tables to work, as Paul apparently wants them
> to, and my current proposal isn't (but let's fix Fclrhash to work on
> non-rehashed hash tables).
> 
> Hash tables without internal free vectors: change the interpretation
> of the hash table API (:size has to be reinterpreted to remain
> meaningful), and some trade-offs about when to use hash tables.
> 
> Four tag bits for "annotated" (e.g., immutable) objects: very far from
> ready, and problematic on 32-bit machines (perhaps this is no longer a
> concern for Emacs 28...)
> 
> Turning pseudovectors into their own tag type, as miscellaneous
> objects: not convinced it's worth the change, yet.

We can still have these on a branch, or on several branches.

> > An alternative would be to make these changes on a branch, and merge
> > that branch when it is sufficiently stable and mature.  Please
> > consider this possibility.  After all, these two issues are not
> > terribly urgent to fix (unlike, say, the unexec thingy).
> 
> I'm not quite sure which "unexec thingy" you're referring to.

A.k.a. "pdumper".



  reply	other threads:[~2019-07-23 14:56 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190721193221.1964.53182@vcs0.savannah.gnu.org>
     [not found] ` <20190721193222.8C19E20BE2@vcs0.savannah.gnu.org>
2019-07-22  4:12   ` [Emacs-diffs] master 5d4dd55: Fix lifetime error in previous patch Pip Cet
2019-07-22 13:40     ` Stefan Monnier
2019-07-23  1:06       ` Paul Eggert
2019-07-22 15:00     ` Changes in GC and in pure space (was: [Emacs-diffs] master 5d4dd55: Fix lifetime error in previous patch) Eli Zaretskii
2019-07-22 17:47       ` Paul Eggert
2019-07-22 18:19         ` Changes in GC and in pure space Eli Zaretskii
2019-07-22 19:58           ` Stefan Monnier
2019-07-23  1:43             ` Paul Eggert
2019-07-23 14:46               ` Eli Zaretskii
2019-07-23 16:27                 ` Paul Eggert
2019-07-23 16:58                   ` Eli Zaretskii
2019-07-23  2:25             ` Eli Zaretskii
2019-07-23  1:29         ` bug#36769: portable dumper mishandles user-defined hashtabs Paul Eggert
2019-07-23  2:06           ` Paul Eggert
2019-07-22 19:05       ` Changes in GC and in pure space (was: [Emacs-diffs] master 5d4dd55: Fix lifetime error in previous patch) Pip Cet
2019-07-23 14:56         ` Eli Zaretskii [this message]
2019-07-23 15:33         ` Changes in GC and in pure space Stefan Monnier
2019-07-24  3:06           ` Richard Stallman
2019-08-15  9:34         ` Changes in GC and in pure space (was: [Emacs-diffs] master 5d4dd55: Fix lifetime error in previous patch) Paul Eggert
2019-08-16 13:34           ` Pip Cet
2019-08-22  0:25             ` Paul Eggert
2019-08-22  2:06             ` Paul Eggert
2019-08-22  5:36             ` Paul Eggert
2019-09-04  6:05             ` Paul Eggert
2019-09-04 14:51               ` Eli Zaretskii
2019-09-04 16:56                 ` Paul Eggert
2019-09-04 17:36                 ` Daniel Colascione
2019-09-04 17:45                 ` Changes in GC and in pure space Stefan Monnier
2019-09-04 18:34                   ` Óscar Fuentes
2019-09-04 19:15                     ` Paul Eggert
2019-09-05  7:04                   ` Paul Eggert
2019-07-24  2:58       ` Changes in GC and in pure space (was: [Emacs-diffs] master 5d4dd55: Fix lifetime error in previous patch) Richard Stallman

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