Received: (at 45200) by debbugs.gnu.org; 12 Dec 2020 20:16:15 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Sat Dec 12 15:16:15 2020 Received: from localhost ([127.0.0.1]:46762 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1koBJP-0001K0-39 for submit <at> debbugs.gnu.org; Sat, 12 Dec 2020 15:16:15 -0500 Received: from eggs.gnu.org ([209.51.188.92]:53982) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <eliz@HIDDEN>) id 1koBJO-0001Jc-42 for 45200 <at> debbugs.gnu.org; Sat, 12 Dec 2020 15:16:14 -0500 Received: from fencepost.gnu.org ([2001:470:142:3::e]:51314) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from <eliz@HIDDEN>) id 1koBJH-0002dH-DS; Sat, 12 Dec 2020 15:16:08 -0500 Received: from [176.228.60.248] (port=1537 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from <eliz@HIDDEN>) id 1koBJG-000875-PR; Sat, 12 Dec 2020 15:16:07 -0500 Date: Sat, 12 Dec 2020 22:15:52 +0200 Message-Id: <83k0tmeq6f.fsf@HIDDEN> From: Eli Zaretskii <eliz@HIDDEN> To: Konstantin Kharlamov <hi-angel@HIDDEN> In-Reply-To: <dd4a240ab3ff14d8f04d02b2504611a4d9f3f816.camel@HIDDEN> (message from Konstantin Kharlamov on Sat, 12 Dec 2020 21:43:10 +0300) Subject: Re: bug#45200: Memory leaks: (garbage-collect) fails to reclaim memory References: <dd4a240ab3ff14d8f04d02b2504611a4d9f3f816.camel@HIDDEN> X-Spam-Score: -2.3 (--) X-Debbugs-Envelope-To: 45200 Cc: 45200 <at> debbugs.gnu.org X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -3.3 (---) > From: Konstantin Kharlamov <hi-angel@HIDDEN> > Date: Sat, 12 Dec 2020 21:43:10 +0300 > > # Steps to reproduce: > > 1. Run `mkdir /tmp/.emacs.d` > 2. Run emacs as `HOME=/tmp/ emacs`, and measure its PSS > 3. Create a file /tmp/.emacs.d/early-init.el with content: > > ;; only run garbage collection on idle > (setq gc-cons-threshold most-positive-fixnum) > (run-with-idle-timer 2 t (lambda () (garbage-collect))) > > 4. Run emacs as `HOME=/tmp/ emacs`, evaluate (garbage-collect), then measure its PSS > > ## Expected > > Size has no statistically-significant difference, because in both cases we garbage-collected memory. > > ## Actual > > Size without calling explicit garbage-collect, from 3 runs, varied around 41.2..41.7 MB. > > Size afterwards, also 3 runs, varied around 45.4..45.5 MB. Could be simply the effect of different stack size, since Emacs's GC is conservative, and when there's doubt whether something is a live object, it won't GC it. I think more specific and detailed evidence is needed to prove your case: which objects were not GC'ed and why.
bug-gnu-emacs@HIDDEN:bug#45200; Package emacs.
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Subject: Memory leaks: (garbage-collect) fails to reclaim memory
From: Konstantin Kharlamov <hi-angel@HIDDEN>
To: bug-gnu-emacs@HIDDEN
Date: Sat, 12 Dec 2020 21:43:10 +0300
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The problem is basically: (garbage-collect) refuses to collect some of the memory. It is more visible if you delay garbage collection, which is what I do for for performance-related reasons. My config has the following snippet:
;; only run garbage collection on idle
(setq gc-cons-threshold most-positive-fixnum)
(run-with-idle-timer 2 t (lambda () (garbage-collect)))
How much memory gets lost depends on configuration. For me right after start the difference is 40 MB: ≈60 MB is Emacs PSS size without above code, and ≈100 MB it is when garbage-collection is delayed, *after* I run explicitly (garbage-collect). It is less visible without any other configs, nonetheless it's visible.
# Steps to reproduce:
1. Run `mkdir /tmp/.emacs.d`
2. Run emacs as `HOME=/tmp/ emacs`, and measure its PSS
3. Create a file /tmp/.emacs.d/early-init.el with content:
;; only run garbage collection on idle
(setq gc-cons-threshold most-positive-fixnum)
(run-with-idle-timer 2 t (lambda () (garbage-collect)))
4. Run emacs as `HOME=/tmp/ emacs`, evaluate (garbage-collect), then measure its PSS
## Expected
Size has no statistically-significant difference, because in both cases we garbage-collected memory.
## Actual
Size without calling explicit garbage-collect, from 3 runs, varied around 41.2..41.7 MB.
Size afterwards, also 3 runs, varied around 45.4..45.5 MB.
This is 4 MB lost. While not much, but as I mentioned it grows as much as to 40MB. The Emacs whose emacslient I'm using to write this email has size 218 MB, and now I wouldn't be surprised if much of that is actually a leaked memory.
# Version
Emacs-git 28.0.50, build from commit abd15e088e99
Konstantin Kharlamov <hi-angel@HIDDEN>:bug-gnu-emacs@HIDDEN.
Full text available.bug-gnu-emacs@HIDDEN:bug#45200; Package emacs.
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