mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Jeff King <>
To: John Cai <>
Cc: git <>, Christian Couder <>
Subject: [PATCH 0/3] reducing fsck memory usage
Date: Thu, 22 Sep 2022 06:09:01 -0400	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, Sep 20, 2022 at 04:41:51PM -0400, Jeff King wrote:

> And this is data we've allocated for trees. It kind of looks like
> fsck_walk_tree() never bothers to clean up the trees it parses, leaving
> the buffers attached to the tree structs. But that can't be the case,
> because linux.git has something like 16GB of trees. These may be entries
> we keep in the internal delta cache, though it should be a bit smaller
> than what you have here (the default is 96MB; you can drop it with
> core.deltaBaseCacheLimit, but runtime may suffer).
> There's a call to free_tree_buffer() in builtin/fsck.c:traverse_one();
> that may be what ends up freeing things. It's been a while since I've
> traced through the call paths for fsck.

I dug into this a bit more. We do indeed free the trees correctly in
most of the code paths, but there's one where we don't, and you can
convince it to hold all of the trees in memory at once (though in
practice few people are likely to hit this case).

So here's a fix for that, plus a cleaned up version of the patch I sent
earlier which should drop your memory usage, plus a bonus small memory
reduction and cleanup in the third patch.

  [1/3]: fsck: free tree buffers after walking unreachable objects
  [2/3]: fsck: turn off save_commit_buffer
  [3/3]: parse_object_buffer(): respect save_commit_buffer

 builtin/fsck.c | 6 +++---
 object.c       | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)


  reply	other threads:[~2022-09-22 10:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20 19:27 [INVESTIGATION] why is fsck --connectivity-only so much more expensive than rev-list --objects --all? John Cai
2022-09-20 20:41 ` Jeff King
2022-09-22 10:09   ` Jeff King [this message]
2022-09-22 10:11     ` [PATCH 1/3] fsck: free tree buffers after walking unreachable objects Jeff King
2022-09-22 18:40       ` Junio C Hamano
2022-09-22 18:58         ` Jeff King
2022-09-22 19:27           ` Junio C Hamano
2022-09-22 22:16             ` Jeff King
2022-09-22 10:13     ` [PATCH 2/3] fsck: turn off save_commit_buffer Jeff King
2022-09-22 10:15     ` [PATCH 3/3] parse_object_buffer(): respect save_commit_buffer Jeff King

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

  List information:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).