From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id C82B21F5AE for ; Thu, 30 Jul 2020 22:24:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730454AbgG3WYw (ORCPT ); Thu, 30 Jul 2020 18:24:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730424AbgG3WYt (ORCPT ); Thu, 30 Jul 2020 18:24:49 -0400 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02F35C061575 for ; Thu, 30 Jul 2020 15:24:49 -0700 (PDT) Received: by mail-wm1-x341.google.com with SMTP id p14so7023731wmg.1 for ; Thu, 30 Jul 2020 15:24:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=/R5LWWXKMmJRdlNwqXfPKs3HG+n52TuWAZYKO2N8KvA=; b=dit74pY4t+qxUdyx6M/ZLbReeNW8q1UjjHRHM5+06QMmiEYNiprxmQElBJXR6AXJ8Z yOvTL+/pQ9RDFx0R5aB6kqQOomteGY+oYCVLN9GE8Z0Cs1IRbFfBlyqz5r4YA1UEs/mU jRKZApj43pFHkztAU8Xu4PtvlYJXPmPYuTGBb/qEXnVJhAjptmk3R2hV/a++SyFYSqLp FFRxPn1WlfjBjPmlH1+FRGdw6qUKsEcAKvtIoRfiE0oTMmx9DYA2EvvIfSq1s9fvIe5v xKBjzFHt8b7MrYOOLFx1k3wVKEP+d9q0eX6GRW5xqCg70rhxd7d8RcS9bLEYVR8AL6R8 24XQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=/R5LWWXKMmJRdlNwqXfPKs3HG+n52TuWAZYKO2N8KvA=; b=G03D4szn1VSXCtOQ4QRdkeWf+o8HhMzcXxglmd8gjCAEN7TY5IaiXDBW7jkjU6cZ8r 6Pi1lBZo2BUyxWUxplYkgKmidFGQZbCfTBtHHPWOyJu6+xp9Fb1gQb46IspReN5nFAb7 Xn5mAP0AOBKIzX2cGLJeUUZIt+3XGIIbT7zk4XszNMmQXL3uGHlTd3lXSDYu54Aor3GS ISEHrSii65PNVpS4k9yK2Daw9X1J30li9hjaPTrkd8g0v68A34NweiqG9UL2jfVNgxKp 1R4x6UNpCf9bapMc5zlkkvnUScl/5hlfy6XE6FpW4WKxY0UozX+sfkPoXRm40/FIw//2 ynwQ== X-Gm-Message-State: AOAM532aLG4bxAB65MrSMbbBMTqydhZI2f5iVWIj33g/6R2OXbPT5OWt f5M1Bz7CG2sgUQnWSAgPaPnyun9v X-Google-Smtp-Source: ABdhPJxu7//6q3j6cv4sSMdh/UdYZSMtpCs574sZN2bFxZv7qn9DcO0+onOJj4MU1bNGFDnMD9OzRA== X-Received: by 2002:a1c:b7c2:: with SMTP id h185mr1221009wmf.168.1596147887319; Thu, 30 Jul 2020 15:24:47 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id l18sm11328819wrm.52.2020.07.30.15.24.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2020 15:24:46 -0700 (PDT) Message-Id: <0128fdfd1ab286ea27437bfe93a9dbb532444277.1596147867.git.gitgitgadget@gmail.com> In-Reply-To: References: From: "Derrick Stolee via GitGitGadget" Date: Thu, 30 Jul 2020 22:24:16 +0000 Subject: [PATCH v3 10/20] maintenance: add loose-objects task Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit MIME-Version: 1.0 To: git@vger.kernel.org Cc: Johannes.Schindelin@gmx.de, sandals@crustytoothpaste.net, steadmon@google.com, jrnieder@gmail.com, peff@peff.net, congdanhqx@gmail.com, phillip.wood123@gmail.com, emilyshaffer@google.com, sluongng@gmail.com, jonathantanmy@google.com, Derrick Stolee , Derrick Stolee Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Derrick Stolee One goal of background maintenance jobs is to allow a user to disable auto-gc (gc.auto=0) but keep their repository in a clean state. Without any cleanup, loose objects will clutter the object database and slow operations. In addition, the loose objects will take up extra space because they are not stored with deltas against similar objects. Create a 'loose-objects' task for the 'git maintenance run' command. This helps clean up loose objects without disrupting concurrent Git commands using the following sequence of events: 1. Run 'git prune-packed' to delete any loose objects that exist in a pack-file. Concurrent commands will prefer the packed version of the object to the loose version. (Of course, there are exceptions for commands that specifically care about the location of an object. These are rare for a user to run on purpose, and we hope a user that has selected background maintenance will not be trying to do foreground maintenance.) 2. Run 'git pack-objects' on a batch of loose objects. These objects are grouped by scanning the loose object directories in lexicographic order until listing all loose objects -or- reaching 50,000 objects. This is more than enough if the loose objects are created only by a user doing normal development. We noticed users with _millions_ of loose objects because VFS for Git downloads blobs on-demand when a file read operation requires populating a virtual file. This has potential of happening in partial clones if someone runs 'git grep' or otherwise evades the batch-download feature for requesting promisor objects. This step is based on a similar step in Scalar [1] and VFS for Git. [1] https://github.com/microsoft/scalar/blob/master/Scalar.Common/Maintenance/LooseObjectsStep.cs Signed-off-by: Derrick Stolee --- Documentation/git-maintenance.txt | 11 ++++ builtin/gc.c | 97 +++++++++++++++++++++++++++++++ t/t7900-maintenance.sh | 39 +++++++++++++ 3 files changed, 147 insertions(+) diff --git a/Documentation/git-maintenance.txt b/Documentation/git-maintenance.txt index d134192fa8..077929b691 100644 --- a/Documentation/git-maintenance.txt +++ b/Documentation/git-maintenance.txt @@ -76,6 +76,17 @@ gc:: It can also be disruptive in some situations, as it deletes stale data. +loose-objects:: + The `loose-objects` job cleans up loose objects and places them into + pack-files. In order to prevent race conditions with concurrent Git + commands, it follows a two-step process. First, it deletes any loose + objects that already exist in a pack-file; concurrent Git processes + will examine the pack-file for the object data instead of the loose + object. Second, it creates a new pack-file (starting with "loose-") + containing a batch of loose objects. The batch size is limited to 50 + thousand objects to prevent the job from taking too long on a + repository with many loose objects. + OPTIONS ------- --auto:: diff --git a/builtin/gc.c b/builtin/gc.c index 1f20428286..96ded73b2f 100644 --- a/builtin/gc.c +++ b/builtin/gc.c @@ -832,6 +832,98 @@ static int maintenance_task_gc(void) return run_command(&child); } +static int prune_packed(void) +{ + struct child_process child = CHILD_PROCESS_INIT; + + child.git_cmd = 1; + strvec_push(&child.args, "prune-packed"); + + if (opts.quiet) + strvec_push(&child.args, "--quiet"); + + return !!run_command(&child); +} + +struct write_loose_object_data { + FILE *in; + int count; + int batch_size; +}; + +static int bail_on_loose(const struct object_id *oid, + const char *path, + void *data) +{ + return 1; +} + +static int write_loose_object_to_stdin(const struct object_id *oid, + const char *path, + void *data) +{ + struct write_loose_object_data *d = (struct write_loose_object_data *)data; + + fprintf(d->in, "%s\n", oid_to_hex(oid)); + + return ++(d->count) > d->batch_size; +} + +static int pack_loose(void) +{ + struct repository *r = the_repository; + int result = 0; + struct write_loose_object_data data; + struct child_process pack_proc = CHILD_PROCESS_INIT; + + /* + * Do not start pack-objects process + * if there are no loose objects. + */ + if (!for_each_loose_file_in_objdir(r->objects->odb->path, + bail_on_loose, + NULL, NULL, NULL)) + return 0; + + pack_proc.git_cmd = 1; + + strvec_push(&pack_proc.args, "pack-objects"); + if (opts.quiet) + strvec_push(&pack_proc.args, "--quiet"); + strvec_pushf(&pack_proc.args, "%s/pack/loose", r->objects->odb->path); + + pack_proc.in = -1; + + if (start_command(&pack_proc)) { + error(_("failed to start 'git pack-objects' process")); + return 1; + } + + data.in = xfdopen(pack_proc.in, "w"); + data.count = 0; + data.batch_size = 50000; + + for_each_loose_file_in_objdir(r->objects->odb->path, + write_loose_object_to_stdin, + NULL, + NULL, + &data); + + fclose(data.in); + + if (finish_command(&pack_proc)) { + error(_("failed to finish 'git pack-objects' process")); + result = 1; + } + + return result; +} + +static int maintenance_task_loose_objects(void) +{ + return prune_packed() || pack_loose(); +} + typedef int maintenance_task_fn(void); struct maintenance_task { @@ -844,6 +936,7 @@ struct maintenance_task { enum maintenance_task_label { TASK_PREFETCH, + TASK_LOOSE_OBJECTS, TASK_GC, TASK_COMMIT_GRAPH, @@ -856,6 +949,10 @@ static struct maintenance_task tasks[] = { "prefetch", maintenance_task_prefetch, }, + [TASK_LOOSE_OBJECTS] = { + "loose-objects", + maintenance_task_loose_objects, + }, [TASK_GC] = { "gc", maintenance_task_gc, diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh index 5294396a24..27a423a4f2 100755 --- a/t/t7900-maintenance.sh +++ b/t/t7900-maintenance.sh @@ -67,4 +67,43 @@ test_expect_success 'prefetch multiple remotes' ' git log prefetch/remote2/two ' +test_expect_success 'loose-objects task' ' + # Repack everything so we know the state of the object dir + git repack -adk && + + # Hack to stop maintenance from running during "git commit" + echo in use >.git/objects/maintenance.lock && + + # Assuming that "git commit" creates at least one loose object + test_commit create-loose-object && + rm .git/objects/maintenance.lock && + + ls .git/objects >obj-dir-before && + test_file_not_empty obj-dir-before && + ls .git/objects/pack/*.pack >packs-before && + test_line_count = 1 packs-before && + + # The first run creates a pack-file + # but does not delete loose objects. + git maintenance run --task=loose-objects && + ls .git/objects >obj-dir-between && + test_cmp obj-dir-before obj-dir-between && + ls .git/objects/pack/*.pack >packs-between && + test_line_count = 2 packs-between && + ls .git/objects/pack/loose-*.pack >loose-packs && + test_line_count = 1 loose-packs && + + # The second run deletes loose objects + # but does not create a pack-file. + git maintenance run --task=loose-objects && + ls .git/objects >obj-dir-after && + cat >expect <<-\EOF && + info + pack + EOF + test_cmp expect obj-dir-after && + ls .git/objects/pack/*.pack >packs-after && + test_cmp packs-between packs-after +' + test_done -- gitgitgadget