Re: [RFC PATCH] object-file.c: batched disk flushes for stream_loose_object()
From: Johannes Schindelin <hidden>
Date: 2022-06-09 09:31:25
Hi, On Thu, 9 Jun 2022, Han Xin wrote:
Neeraj Singh[1] pointed out that if batch fsync is enabled, we should still call prepare_loose_object_bulk_checkin() to potentially create the bulk checkin objdir. 1. https://lore.kernel.org/git/7ba4858a-d1cc-a4eb-b6d6-4c04a5dd6ce7@gmail.com/ (local) Signed-off-by: Han Xin <redacted>
I like a good commit message that is concise and yet has all the necessary information. Well done!
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--- object-file.c | 3 +++ t/t5351-unpack-large-objects.sh | 15 ++++++++++++++- 2 files changed, 17 insertions(+), 1 deletion(-)diff --git a/object-file.c b/object-file.c index 2dd828b45b..3a1be74775 100644 --- a/object-file.c +++ b/object-file.c@@ -2131,6 +2131,9 @@ int stream_loose_object(struct input_stream *in_stream, size_t len, char hdr[MAX_HEADER_LEN]; int hdrlen; + if (batch_fsync_enabled(FSYNC_COMPONENT_LOOSE_OBJECT)) + prepare_loose_object_bulk_checkin(); +
Makes sense.
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/* Since oid is not determined, save tmp file to odb path. */ strbuf_addf(&filename, "%s/", get_object_directory()); hdrlen = format_object_header(hdr, sizeof(hdr), OBJ_BLOB, len);diff --git a/t/t5351-unpack-large-objects.sh b/t/t5351-unpack-large-objects.sh index 461ca060b2..a66a51f7df 100755 --- a/t/t5351-unpack-large-objects.sh +++ b/t/t5351-unpack-large-objects.sh@@ -18,7 +18,10 @@ test_expect_success "create large objects (1.5 MB) and PACK" ' test_commit --append foo big-blob && test-tool genrandom bar 1500000 >big-blob && test_commit --append bar big-blob && - PACK=$(echo HEAD | git pack-objects --revs pack) + PACK=$(echo HEAD | git pack-objects --revs pack) && + git verify-pack -v pack-$PACK.pack | + grep -E "commit|tree|blob" | + sed -n -e "s/^\([0-9a-f]*\).*/\1/p" >obj-list
Here, I would recommend avoiding the pipe, to ensure that we would catch problems in the `verify-pack` invocation, and I think we can avoid the `grep` altogether: git verify-pack -v pack-$PACK.pack >out && sed -n 's/^\([0-9a-f][0-9a-f]*\).*\(commit\|tree\|blob\)/\1/p' \ <out >obj-list
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' test_expect_success 'set memory limitation to 1MB' '@@ -45,6 +48,16 @@ test_expect_success 'unpack big object in stream' ' test_dir_is_empty dest.git/objects/pack ' +BATCH_CONFIGURATION='-c core.fsync=loose-object -c core.fsyncmethod=batch' + +test_expect_success 'unpack big object in stream (core.fsyncmethod=batch)' ' + prepare_dest 1m && + git $BATCH_CONFIGURATION -C dest.git unpack-objects <pack-$PACK.pack &&
I think the canonical way would be to use `test_config core.fsync ...`, but the presented way works, too.
+ test_dir_is_empty dest.git/objects/pack && + git -C dest.git cat-file --batch-check="%(objectname)" <obj-list >current &&
Good. The `--batch-check="%(objectname)"` part forces `cat-file` to read the actual object.
+ cmp obj-list current +'
My main question about this test case is whether it _actually_ verifies that the batch-mode `fsync()`ing took place. I kind of had expected to see Trace2 enabled and a `grep` for `fsync/hardware-flush`. Do you think that would still make sense to add? Thank you for working on the `fsync()` aspects of Git! Dscho
+ test_expect_success 'do not unpack existing large objects' ' prepare_dest 1m && git -C dest.git index-pack --stdin <pack-$PACK.pack && -- 2.36.1