From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 306B04FE2D2 for ; Tue, 13 Oct 2026 12:07:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893279; cv=none; b=suZmf880Cguckzpt2y9l3KcuPbohGU401uIe6ggUXmohH5w+DrA5ScX07rkOoU25+iszuz64zYw9STt88/ykW0WE7Pl5v78DJ892Mg72yveEjKMXttbpEJvnKxRwrNwftkVLrkAG00DfLB61Y1V4xyn5uq+48nv51KGVFrPX0Pc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893279; c=relaxed/simple; bh=x5mVYq9a9g0vFy8tFmJh3GCyqww6NYdyJO9fqlVSNbM=; h=Message-Id:In-Reply-To:References:From:Date:Subject:Content-Type: MIME-Version:To:Cc; b=i9xxOljhqTG5J+zgRRq1Kd7z/QdnfEyaaJ4A30KjsLO/wml9Z4cJZO1cyKTAlKIdTvZ3KagtXo9TtujhyjbUT9D3umOxUHtfs+/F5H03ur0HGSU0HGuGNt1A6g8dt4ucPA0lhjGnquN2Ji3yY/SHgTZukOMd3BBTfeYu3EupGKc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Y5/yx/Fe; arc=none smtp.client-ip=209.85.216.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Y5/yx/Fe" Received: by mail-pj1-f46.google.com with SMTP id 98e67ed59e1d1-3ab752f6244so2307946a91.2 for ; Tue, 13 Oct 2026 05:07:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1791893278; x=1792498078; darn=vger.kernel.org; h=cc:to:mime-version:content-transfer-encoding:content-type:fcc :subject:date:from:references:in-reply-to:message-id:from:to:cc :subject:date:message-id:reply-to:content-type; bh=YkbZijw5mwT1PpIL3niKHI0cVd83KclI50y/REcLdd4=; b=Y5/yx/FeF7jlcjhFyLto6GTQNLgCQltfn49naXJ2BtVrKmi44hQlSCag0IaThHW26w P3dLPvmqMiKTmJSMfLaCXBPPNq36tzdiQNBBxSwFRFwlJfZ6LsgpSQccgv/ZQdAUaTS6 8iQWTW/LeqIxG6kedEEqYDgPlxlk0vfuzNQkzoWKP2OZEQoSKGKRrdh0f1MR9JXpv3eO 4gE5Z1yMQu+xGjlTesIR2I6mQdFmnVgqSCOJC5AMpoMUbeiT9hJLClc8gfOxlLyn8hBg 7UC1JMu4L5SrnxKMGD5W5ayXLzZVgJn/Akobajb743DJGvj5DLwtUCae6M3XZ3aDFozE eEKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791893278; x=1792498078; h=cc:to:mime-version:content-transfer-encoding:content-type:fcc :subject:date:from:references:in-reply-to:message-id:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=YkbZijw5mwT1PpIL3niKHI0cVd83KclI50y/REcLdd4=; b=q3j21HmdoMJ8MO750myzw/tWm8AY5hOj/s0rUlwvK0kKgfHuutBCCWZS01jhPYlRqE nQoRO9hWvRT6cmtfEMCACSTPJ+Smr17eQiZtoACBQHTDapY12jQaRkG8Yr734EatObgS YF6qAbxCl5jC0YSGxi3gssr2DAJJdY15gUQFJVTgPzdrtxJTMM0QLWfvKj++aP7wYHwK dfCutighDDAWxnEkrkdZ2D5Kvnzyz1k0ItjNY0wgWRqs1PrLt5j9n+1s9gDi0dNJUA6K VY1Xk9Z8fe3bHEDE0rZZ0MzpHutEkFYF/IRjJ821HbOhUY8W08iRy6s4SW23KpWvHkhH MEkQ== X-Gm-Message-State: AFq9FYJwbyQ1Mw09z07aQuPBLm9XnkqcmnJFo340k8NW5VFSiUu2UWmu mJI5AmfJJvJWSkslCdOLcznNbrEmFQusogl/igXyfgcGbKsJKAOGy54ij1CM1Q== X-Gm-Gg: AYBFou25UJ5PV1YtcGDOJhnZlhgVaCQmgob0OsNPHQcVQ/sJEI6lvbosJSfSgqltJuL pnoiAZI2OL2U/+FNuQRa50opJZKThKuy+BWwyR7rG8b37vmoEyibbtfjwbaFDlp0paIKQYJgEAs nAx4yrJ1rS8AmrpQOTtwqDAIcjwBaFf4J2xqxe/HOoGI1NPVgpQkQe9QKNvcQxqnM0QWNxIAfMW KQxeSTvsLP8JcvzzvqenOJKo7hgQpDNLj53RsbxO10ATbs8xPXvHEQKwcZXCPkiPeUk+2D/UeGJ uEtPdp7yKsbJhZXdRoPLwHXSY+Vq3jg58hplKIOurlNgf2U3wRUDfRBC69SCrfWCB8gfOYVxC05 WSuWGICpAKpSctcjr06Uw+I4+8mh+IkFWtldyNhbL6nGczOvVOLLlHudE0RBYS9yPCEUoDHoK+V qZ79Mp7EGtq6nyn+f2Ib3T9ebHmsA+7XPO/b+bzkJEr7YJw0aeymjAGgaWkKiUyY7RgPZRuRZ0h ss= X-Received: by 2002:a17:90b:2ec4:b0:39e:574d:3d2f with SMTP id 98e67ed59e1d1-3ab3a39ee2fmr10521712a91.7.1791893277485; Tue, 13 Oct 2026 05:07:57 -0700 (PDT) Received: from [127.0.0.1] ([52.159.247.232]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ab36ca0033sm20748094a91.2.2026.10.13.05.07.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Oct 2026 05:07:56 -0700 (PDT) Message-Id: <06f6c774391bf8d6d40a30d0b7fef6c80596afca.1791893274.git.gitgitgadget@gmail.com> In-Reply-To: References: From: "Thomas Bachem via GitGitGadget" Date: Tue, 13 Oct 2026 12:07:52 +0000 Subject: [PATCH v8 1/2] rerere: wait for MERGE_RR.lock before giving up Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 To: git@vger.kernel.org Cc: Patrick Steinhardt , Phillip Wood , Junio C Hamano , Phillip Wood , Thomas Bachem , Thomas Bachem From: Thomas Bachem setup_rerere() takes MERGE_RR.lock with LOCK_DIE_ON_ERROR, so when two processes want it at the same time, the second one dies. That used to be rare. Since 452b12c2e0 (builtin/maintenance: use "geometric" strategy by default, 2026-02-24) the auto maintenance after a commit runs "git rerere gc" whenever rr-cache has enough stale entries, and the gc holds the lock while it prunes. If a rebase's next pick conflicts while the gc holds the lock, the rebase dies inside repo_rerere(), before the sequencer has written what "git rebase --continue" needs. Every later "git rebase --continue" then fails with "you have staged changes in your working tree". Wait for the lock for up to rerere.lockTimeout milliseconds, 1000 by default, and only then fail as before. Pruning a few thousand entries takes well under a second, so the default covers a rebase that runs into the gc. Assisted-by: Claude Fable 5.1 Signed-off-by: Thomas Bachem --- Documentation/config/rerere.adoc | 7 +++++ rerere.c | 22 ++++++++++--- t/t4200-rerere.sh | 53 ++++++++++++++++++++++++++++++++ 3 files changed, 77 insertions(+), 5 deletions(-) diff --git a/Documentation/config/rerere.adoc b/Documentation/config/rerere.adoc index 3a78b5ebb1..ab035e2d7d 100644 --- a/Documentation/config/rerere.adoc +++ b/Documentation/config/rerere.adoc @@ -10,3 +10,10 @@ rerere.enabled:: enabled if there is an `rr-cache` directory under the `$GIT_DIR`, e.g. if "rerere" was previously used in the repository. + +rerere.lockTimeout:: + The length of time, in milliseconds, to wait for the rerere + lock when another process holds it, typically a background + `git rerere gc`. Value 0 means not to wait at all; -1 means + to wait indefinitely. Default is 1000 (i.e., wait for 1 + second). diff --git a/rerere.c b/rerere.c index 1c3745d9e3..64fac07c71 100644 --- a/rerere.c +++ b/rerere.c @@ -33,6 +33,9 @@ static int rerere_enabled = -1; /* automatically update cleanly resolved paths to the index */ static int rerere_autoupdate; +/* how long to wait for MERGE_RR.lock, in milliseconds */ +static int rerere_lock_timeout_ms = 1000; + #define RR_HAS_POSTIMAGE 1 #define RR_HAS_PREIMAGE 2 struct rerere_dir { @@ -850,6 +853,8 @@ static void git_rerere_config(void) { repo_config_get_bool(the_repository, "rerere.enabled", &rerere_enabled); repo_config_get_bool(the_repository, "rerere.autoupdate", &rerere_autoupdate); + repo_config_get_int(the_repository, "rerere.locktimeout", + &rerere_lock_timeout_ms); repo_config(the_repository, git_default_config, NULL); } @@ -882,12 +887,19 @@ int setup_rerere(struct repository *r, struct string_list *merge_rr, int flags) if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE)) rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE); - if (flags & RERERE_READONLY) + if (flags & RERERE_READONLY) { fd = 0; - else - fd = repo_hold_lock_file_for_update(r, &write_lock, - git_path_merge_rr(r), - LOCK_DIE_ON_ERROR); + } else { + /* + * Another process may hold the lock for a while, e.g. + * "git rerere gc" while it prunes rr-cache, so wait for + * it instead of dying right away. + */ + fd = repo_hold_lock_file_for_update_timeout(r, &write_lock, + git_path_merge_rr(r), + LOCK_DIE_ON_ERROR, + rerere_lock_timeout_ms); + } read_rr(r, merge_rr); return fd; } diff --git a/t/t4200-rerere.sh b/t/t4200-rerere.sh index 7bb601e117..94165c8417 100755 --- a/t/t4200-rerere.sh +++ b/t/t4200-rerere.sh @@ -242,6 +242,59 @@ test_expect_success 'old records rest in peace' ' test_path_is_missing $rr2/preimage ' +test_expect_success 'a held lock is waited out within rerere.lockTimeout' ' + git reset --hard && + rm -rf $rr && + test_when_finished "wait && rm -f .git/MERGE_RR.lock" && + >.git/MERGE_RR.lock && + { + ( sleep 1 && rm -f .git/MERGE_RR.lock ) & + } && + test_must_fail git -c rerere.lockTimeout=5000 merge first 2>err && + test_grep ! "Unable to create.*MERGE_RR\.lock" err && + test_grep "^=======\$" $rr/preimage +' + +test_expect_success 'merge fails on a lock it cannot take' ' + git reset --hard && + rm -rf $rr && + test_when_finished "rm -f .git/MERGE_RR.lock" && + >.git/MERGE_RR.lock && + test_must_fail git -c rerere.lockTimeout=0 merge first 2>err && + test_grep "Unable to create.*MERGE_RR\.lock" err && + test_grep "^=======\$" a1 && + test_path_is_missing $rr/preimage +' + +test_expect_success 'rerere, forget, clear and gc fail on a lock they cannot take' ' + test_when_finished "rm -f .git/MERGE_RR.lock" && + >.git/MERGE_RR.lock && + test_must_fail git -c rerere.lockTimeout=0 rerere 2>err && + test_grep "Unable to create.*MERGE_RR\.lock" err && + test_must_fail git -c rerere.lockTimeout=0 rerere forget a1 2>err && + test_grep "Unable to create.*MERGE_RR\.lock" err && + test_must_fail git -c rerere.lockTimeout=0 rerere clear 2>err && + test_grep "Unable to create.*MERGE_RR\.lock" err && + test_must_fail git -c rerere.lockTimeout=0 rerere gc 2>err && + test_grep "Unable to create.*MERGE_RR\.lock" err +' + +test_expect_success 'rebase --abort fails on a lock it cannot take' ' + git reset --hard && + git checkout -b lock-held-abort third && + test_when_finished "git checkout third && git branch -D lock-held-abort" && + test_must_fail git rebase first && + test_when_finished "test_might_fail git rebase --abort" && + test_when_finished "rm -f .git/MERGE_RR.lock" && + >.git/MERGE_RR.lock && + test_must_fail git -c rerere.lockTimeout=0 rebase --abort 2>err && + test_grep "Unable to create.*MERGE_RR\.lock" err && + test_path_is_dir .git/rebase-merge && + rm .git/MERGE_RR.lock && + git rebase --abort && + test_path_is_missing .git/rebase-merge +' + rerere_gc_custom_expiry_test () { five_days="$1" right_now="$2" test_expect_success "rerere gc with custom expiry ($five_days, $right_now)" ' -- gitgitgadget