[PATCH v4 0/8] use oidset for skiplist + docs + tests + comment support
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Aug 28, 2018, 09:52 UTC
- Message-ID
- <20180828095219.23296-1-avarab@gmail.com>
- In-Reply-To
- <87lg8refcr.fsf@evledraar.gmail.com>
On Mon, Aug 27 2018, Ævar Arnfjörð Bjarmason wrote:
Show 7 quoted lines
> On Mon, Aug 27 2018, Ævar Arnfjörð Bjarmason wrote: > Does that just mean that when cloning with --recursive with > transfer.fsckObjects=true we'll re-read the file for each "clone" > invocation, both for the main project and everything listed in > .gitmodules? > > If so, I think something like this commit message would be clearer:
Here's a version that does that, I also integrated the perf test René wrote and used it in the commit messages. The range-diff with v3 follows:
1: 09b52b0eae = 1: ba9ef73304 fsck tests: setup of bogus commit object
2: 294a4dfd69 = 2: 1d20e37d3f fsck tests: add a test for no skipList input
3: 15a6e16dc1 = 3: 953ad29f6d fsck: document and test sorted skipList input
4: b93fe502c3 = 4: c8a0bd1555 fsck: document and test commented & empty line skipList input
-: ---------- > 5: cbbb0326d3 fsck: add a performance test for skipList
5: 3cf7d4e9eb ! 6: ca6aca2994 fsck: use strbuf_getline() to read skiplist file
@@ -2,14 +2,33 @@
fsck: use strbuf_getline() to read skiplist file
- buffer is unlikely to contain a NUL character, so printing its contents
- using %s in a die() format is unsafe (detected with ASan).
+ The buffer is unlikely to contain a NUL character, so printing its
+ contents using %s in a die() format is unsafe (detected with ASan).
Use an idiomatic strbuf_getline() loop instead, which ensures the buffer
is always NUL-terminated, supports CRLF files as well, accepts files
without a newline after the last line, supports any hash length
automatically, and is shorter.
+ This fixes a bug where emitting an error about an invalid line on say
+ line 1 would continue printing subsequent lines, and usually continue
+ into uninitialized memory.
+
+ The performance impact of this, on a CentOS 7 box with RedHat GCC
+ 4.8.5-28:
+
+ $ GIT_PERF_REPEAT_COUNT=5 GIT_PERF_MAKE_OPTS='-j56 CFLAGS="-O3"' ./run HEAD~ HEAD p1450-fsck-skip-list.sh
+ Test HEAD~ HEAD
+ ----------------------------------------------------------------------------------------
+ 1450.3: fsck with 0 skipped bad commits 7.75(7.39+0.35) 7.68(7.29+0.39) -0.9%
+ 1450.5: fsck with 1 skipped bad commits 7.70(7.30+0.40) 7.80(7.42+0.37) +1.3%
+ 1450.7: fsck with 10 skipped bad commits 7.77(7.37+0.40) 7.87(7.47+0.40) +1.3%
+ 1450.9: fsck with 100 skipped bad commits 7.82(7.41+0.40) 7.88(7.43+0.44) +0.8%
+ 1450.11: fsck with 1000 skipped bad commits 7.88(7.49+0.39) 7.84(7.43+0.40) -0.5%
+ 1450.13: fsck with 10000 skipped bad commits 8.02(7.63+0.39) 8.07(7.67+0.39) +0.6%
+ 1450.15: fsck with 100000 skipped bad commits 8.01(7.60+0.41) 8.08(7.70+0.38) +0.9%
+ 1450.17: fsck with 1000000 skipped bad commits 7.60(7.10+0.50) 7.37(7.18+0.19) -3.0%
+
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
6: bd51de7c14 ! 7: 58bfd04d96 fsck: use oidset for skiplist
@@ -1,22 +1,33 @@
Author: René Scharfe <l.s.r@web.de>
- fsck: use oidset for skiplist
+ fsck: use oidset instead of oid_array for skipList
- Object IDs to skip are stored in a shared static oid_array. Lookups do
- a binary search on the sorted array. The code checks if the object IDs
- are already in the correct order while loading and skips sorting in that
- case. Lookups are done before reporting a (non-fatal) corruption and
- before checking .gitmodules files.
+ Change the implementation of the skipList feature to use oidset
+ instead of oid_array to store SHA-1s for later lookup.
- Simplify the code by using an oidset instead. Memory usage is a bit
- higher, but we don't need to worry about any sort order anymore. Embed
- the oidset into struct fsck_options to make its ownership clear (no
- hidden sharing) and avoid unnecessary pointer indirection.
+ This list is parsed once on startup by fsck, fetch-pack or
+ receive-pack depending on the *.skipList config in use. I.e. only once
+ per invocation, but note that for "clone --recurse-submodules" each
+ submodule will re-parse the list, in addition to the main project.
- Performance on repositories with a low number of reported issues and
- .gitmodules files (i.e. the usual case) won't be affected much. The
- oidset should be a bit quicker with higher numbers of bad objects in
- the skipList.
+ Memory usage is a bit higher, but we don't need to keep track of the
+ sort order anymore. Embed the oidset into struct fsck_options to make
+ its ownership clear (no hidden sharing) and avoid unnecessary pointer
+ indirection.
+
+ The cumulative impact on performance of this & the preceding change,
+ using the test setup described in the previous commit:
+
+ Test HEAD~2 HEAD~ HEAD
+ ----------------------------------------------------------------------------------------------------------------
+ 1450.3: fsck with 0 skipped bad commits 7.70(7.31+0.38) 7.72(7.33+0.38) +0.3% 7.70(7.30+0.40) +0.0%
+ 1450.5: fsck with 1 skipped bad commits 7.84(7.47+0.37) 7.69(7.32+0.36) -1.9% 7.71(7.29+0.41) -1.7%
+ 1450.7: fsck with 10 skipped bad commits 7.81(7.40+0.40) 7.94(7.57+0.36) +1.7% 7.92(7.55+0.37) +1.4%
+ 1450.9: fsck with 100 skipped bad commits 7.81(7.42+0.38) 7.95(7.53+0.41) +1.8% 7.83(7.42+0.41) +0.3%
+ 1450.11: fsck with 1000 skipped bad commits 7.99(7.62+0.36) 7.90(7.50+0.40) -1.1% 7.86(7.49+0.37) -1.6%
+ 1450.13: fsck with 10000 skipped bad commits 7.98(7.57+0.40) 7.94(7.53+0.40) -0.5% 7.90(7.45+0.44) -1.0%
+ 1450.15: fsck with 100000 skipped bad commits 7.97(7.57+0.39) 8.03(7.67+0.36) +0.8% 7.84(7.43+0.41) -1.6%
+ 1450.17: fsck with 1000000 skipped bad commits 7.72(7.22+0.50) 7.28(7.07+0.20) -5.7% 7.13(6.87+0.25) -7.6%
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
7: 17838cf68c ! 8: 0125461f13 fsck: support comments & empty lines in skipList
@@ -11,6 +11,20 @@
since this on-disk format can be expected to be used by multiple
versions of git.
+ There is no notable performance impact from this change, using the
+ test setup described a couple of commist back:
+
+ Test HEAD~ HEAD
+ ----------------------------------------------------------------------------------------
+ 1450.3: fsck with 0 skipped bad commits 7.81(7.42+0.39) 7.72(7.34+0.38) -1.2%
+ 1450.5: fsck with 1 skipped bad commits 7.75(7.36+0.38) 7.66(7.26+0.39) -1.2%
+ 1450.7: fsck with 10 skipped bad commits 7.81(7.43+0.38) 7.70(7.30+0.39) -1.4%
+ 1450.9: fsck with 100 skipped bad commits 7.85(7.42+0.42) 7.73(7.31+0.41) -1.5%
+ 1450.11: fsck with 1000 skipped bad commits 7.81(7.43+0.38) 7.84(7.46+0.38) +0.4%
+ 1450.13: fsck with 10000 skipped bad commits 7.87(7.47+0.40) 7.86(7.46+0.40) -0.1%
+ 1450.15: fsck with 100000 skipped bad commits 7.77(7.39+0.38) 7.83(7.48+0.34) +0.8%
+ 1450.17: fsck with 1000000 skipped bad commits 7.17(6.92+0.24) 7.11(6.85+0.26) -0.8%
+
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
diff --git a/Documentation/config.txt b/Documentation/config.txtRené Scharfe (3): fsck: add a performance test for skipList fsck: use strbuf_getline() to read skiplist file fsck: use oidset instead of oid_array for skipList
Ævar Arnfjörð Bjarmason (5): fsck tests: setup of bogus commit object fsck tests: add a test for no skipList input fsck: document and test sorted skipList input fsck: document and test commented & empty line skipList input fsck: support comments & empty lines in skipList
Documentation/config.txt | 22 ++++++++++---- fsck.c | 48 ++++++++++------------------- fsck.h | 8 +++-- t/perf/p1450-fsck-skip-list.sh | 40 +++++++++++++++++++++++++ t/t5504-fetch-receive-strict.sh | 53 ++++++++++++++++++++++++++++++--- 5 files changed, 126 insertions(+), 45 deletions(-) create mode 100755 t/perf/p1450-fsck-skip-list.sh
-- 2.19.0.rc0.228.g281dcd1b4d0