From patchwork Thu Jan 20 11:21:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Han Xin X-Patchwork-Id: 12718536 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DB6AC433F5 for ; Thu, 20 Jan 2022 11:22:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231173AbiATLWr (ORCPT ); Thu, 20 Jan 2022 06:22:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231233AbiATLWo (ORCPT ); Thu, 20 Jan 2022 06:22:44 -0500 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D544C06175D for ; Thu, 20 Jan 2022 03:22:30 -0800 (PST) Received: by mail-pf1-x431.google.com with SMTP id i17so5224183pfk.11 for ; Thu, 20 Jan 2022 03:22:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=PTAZHWjWzKv9abjH/CePc2uNxRFWpH0jwXf9oaBslEk=; b=l+RO9+w1CSK77Tx+D+7N0M+rXzd/JXGuqInWsp1lq+kTi9ScSKWq+BcD3vosK3aR4w w/2bp/VOyk4+7F6yyd1h6q+vplovIuTuYmVSgqTKzr+OGmXkVkqYHH7YluQmTk4bB4XM OzgXxaMfBxPdUklAkRQ1sl6Sr41BDV+WsjsGAuKsNswr03CX/o5FdxseORrFE3GkJILy JTS5n+ydQSTUsq2L4t7gw36KE/o/TOXlXvgz3wwJ82AzvkYIlG09i/l2eitlmwKVc8Ff nKLKBiK/PlRIcu5cXWnTDzpAy+MI1onJdd+ytrZd7pRHonu8Jt+d1lUkrHPh15WCCBH8 oNiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=PTAZHWjWzKv9abjH/CePc2uNxRFWpH0jwXf9oaBslEk=; b=py4Ukoo94G4H8aIyR8iJyXpHhi5WZRqDNFGE+LBoLIUTPLszJoaiZn5H0tv4g8gyco b1LHD1pJb0wcO/sx3pbs7Png38G5or5fwyb+/Wd/NkC43KiWKjdASNf8YeLQhhKHhdfw 2HSd4hQ5O1W+9SEVOzsQ7TDnpHFYUvmGA9s6VliFHn2JKZ9DyTPPCvgeyfWufIXKgKvN QWf9EOYJCHaCpvzezh8MAoHXvOSXG/ATqy8lN9HWNRkYq57EJggSPjt4C9yjqxzlGICM 60jPkNtbfkonnYSvCChkWYpDqRAFjYp1zrMPP/p5I2XkN348DgkyCmJRJrAafoxG4ZEz INyA== X-Gm-Message-State: AOAM530RzvDX5/StX07+blqcLe5XmjmZSonLrDgic4NpRv1gLHhj5AEJ vOqEWDCTD5lzLgLM4wQy0/A= X-Google-Smtp-Source: ABdhPJyMVofh7B70gEi2jn+sR09JvGEkYknTmIM1iZa3iWtNrt84+83IuCDFCljQ057oQlaZ4QVa9g== X-Received: by 2002:a63:1d1:: with SMTP id 200mr16570844pgb.290.1642677749707; Thu, 20 Jan 2022 03:22:29 -0800 (PST) Received: from localhost.localdomain ([58.100.34.57]) by smtp.gmail.com with ESMTPSA id x18sm2998989pfh.192.2022.01.20.03.22.26 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Jan 2022 03:22:29 -0800 (PST) From: Han Xin To: Junio C Hamano , Git List , Jeff King , Jiang Xin , Philip Oakley , =?utf-8?b?w4Z2YXIgQXJuZmrDtnLDsCBC?= =?utf-8?b?amFybWFzb24=?= , Derrick Stolee , =?utf-8?q?Ren=C3=A9_Scharfe?= , Jiang Xin Cc: Han Xin Subject: [PATCH v9 1/5] unpack-objects: low memory footprint for get_data() in dry_run mode Date: Thu, 20 Jan 2022 19:21:10 +0800 Message-Id: <20220120112114.47618-2-chiyutianyi@gmail.com> X-Mailer: git-send-email 2.34.1.52.gc288e771b4.agit.6.5.6 In-Reply-To: <20220108085419.79682-1-chiyutianyi@gmail.com> References: <20220108085419.79682-1-chiyutianyi@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han Xin As the name implies, "get_data(size)" will allocate and return a given size of memory. Allocating memory for a large blob object may cause the system to run out of memory. Before preparing to replace calling of "get_data()" to unpack large blob objects in latter commits, refactor "get_data()" to reduce memory footprint for dry_run mode. Because in dry_run mode, "get_data()" is only used to check the integrity of data, and the returned buffer is not used at all, we can allocate a smaller buffer and reuse it as zstream output. Therefore, in dry_run mode, "get_data()" will release the allocated buffer and return NULL instead of returning garbage data. Suggested-by: Jiang Xin Signed-off-by: Han Xin --- builtin/unpack-objects.c | 39 +++++++++++++++++++-------- t/t5328-unpack-large-objects.sh | 48 +++++++++++++++++++++++++++++++++ 2 files changed, 76 insertions(+), 11 deletions(-) create mode 100755 t/t5328-unpack-large-objects.sh diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c index 4a9466295b..c6d6c17072 100644 --- a/builtin/unpack-objects.c +++ b/builtin/unpack-objects.c @@ -96,15 +96,31 @@ static void use(int bytes) display_throughput(progress, consumed_bytes); } +/* + * Decompress zstream from stdin and return specific size of data. + * The caller is responsible to free the returned buffer. + * + * But for dry_run mode, "get_data()" is only used to check the + * integrity of data, and the returned buffer is not used at all. + * Therefore, in dry_run mode, "get_data()" will release the small + * allocated buffer which is reused to hold temporary zstream output + * and return NULL instead of returning garbage data. + */ static void *get_data(unsigned long size) { git_zstream stream; - void *buf = xmallocz(size); + unsigned long bufsize; + void *buf; memset(&stream, 0, sizeof(stream)); + if (dry_run && size > 8192) + bufsize = 8192; + else + bufsize = size; + buf = xmallocz(bufsize); stream.next_out = buf; - stream.avail_out = size; + stream.avail_out = bufsize; stream.next_in = fill(1); stream.avail_in = len; git_inflate_init(&stream); @@ -124,8 +140,15 @@ static void *get_data(unsigned long size) } stream.next_in = fill(1); stream.avail_in = len; + if (dry_run) { + /* reuse the buffer in dry_run mode */ + stream.next_out = buf; + stream.avail_out = bufsize; + } } git_inflate_end(&stream); + if (dry_run) + FREE_AND_NULL(buf); return buf; } @@ -325,10 +348,8 @@ static void unpack_non_delta_entry(enum object_type type, unsigned long size, { void *buf = get_data(size); - if (!dry_run && buf) + if (buf) write_object(nr, type, buf, size); - else - free(buf); } static int resolve_against_held(unsigned nr, const struct object_id *base, @@ -358,10 +379,8 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size, oidread(&base_oid, fill(the_hash_algo->rawsz)); use(the_hash_algo->rawsz); delta_data = get_data(delta_size); - if (dry_run || !delta_data) { - free(delta_data); + if (!delta_data) return; - } if (has_object_file(&base_oid)) ; /* Ok we have this one */ else if (resolve_against_held(nr, &base_oid, @@ -397,10 +416,8 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size, die("offset value out of bound for delta base object"); delta_data = get_data(delta_size); - if (dry_run || !delta_data) { - free(delta_data); + if (!delta_data) return; - } lo = 0; hi = nr; while (lo < hi) { diff --git a/t/t5328-unpack-large-objects.sh b/t/t5328-unpack-large-objects.sh new file mode 100755 index 0000000000..45a3316e06 --- /dev/null +++ b/t/t5328-unpack-large-objects.sh @@ -0,0 +1,48 @@ +#!/bin/sh +# +# Copyright (c) 2022 Han Xin +# + +test_description='git unpack-objects with large objects' + +. ./test-lib.sh + +prepare_dest () { + test_when_finished "rm -rf dest.git" && + git init --bare dest.git +} + +test_no_loose () { + glob=dest.git/objects/?? && + echo "$glob" >expect && + eval "echo $glob" >actual && + test_cmp expect actual +} + +test_expect_success "create large objects (1.5 MB) and PACK" ' + test-tool genrandom foo 1500000 >big-blob && + test_commit --append foo big-blob && + test-tool genrandom bar 1500000 >big-blob && + test_commit --append bar big-blob && + PACK=$(echo HEAD | git pack-objects --revs test) +' + +test_expect_success 'set memory limitation to 1MB' ' + GIT_ALLOC_LIMIT=1m && + export GIT_ALLOC_LIMIT +' + +test_expect_success 'unpack-objects failed under memory limitation' ' + prepare_dest && + test_must_fail git -C dest.git unpack-objects err && + grep "fatal: attempting to allocate" err +' + +test_expect_success 'unpack-objects works with memory limitation in dry-run mode' ' + prepare_dest && + git -C dest.git unpack-objects -n