[PATCH v3 0/2] perf: show that wildmatch() regressed for pathological cases in v2.0

[PATCH v3 0/2] perf: show that wildmatch() regressed for pathological cases in v2.0

[Ævar Arnfjörð Bjarmason]

Fixes the issues noted in v3, see
<20170510225316.31680-1-avarab@gmail.com>
(https://public-inbox.org/git/20170510225316.31680-1-avarab@gmail.com/).

In addition I was wrong about for-each-ref not being subjected to this
slowdown, I was just screwing up the testcase. Fix that. Now:

    $ GIT_PERF_REPEAT_COUNT=1 GIT_PERF_MAKE_OPTS="-j6 NO_OPENSSL=Y NO_WILDMATCH=YesPlease" ./run v1.9.5 v2.12.0 p0100-globbing.sh
    Test                                                       v1.9.5            v2.12.0
    -------------------------------------------------------------------------------------------------
    0100.2: refglob((a*)^nb) against tag (a^100).t; n = 1      0.00(0.00+0.00)   0.00(0.00+0.00) =
    0100.3: refglob((a*)^nb) against tag (a^100).t; n = 2      0.00(0.00+0.00)   0.00(0.00+0.00) =
    0100.4: refglob((a*)^nb) against tag (a^100).t; n = 3      0.00(0.00+0.00)   0.00(0.00+0.00) =
    0100.5: refglob((a*)^nb) against tag (a^100).t; n = 4      0.00(0.00+0.00)   0.01(0.00+0.00) +inf
    0100.6: refglob((a*)^nb) against tag (a^100).t; n = 5      0.00(0.00+0.00)   0.16(0.15+0.00) +inf
    0100.7: refglob((a*)^nb) against tag (a^100).t; n = 6      0.00(0.00+0.00)   2.73(2.71+0.00) +inf
    0100.8: fileglob((a*)^nb) against file (a^100).t; n = 1    0.00(0.00+0.00)   0.00(0.00+0.00) =
    0100.9: fileglob((a*)^nb) against file (a^100).t; n = 2    0.00(0.00+0.00)   0.00(0.00+0.00) =
    0100.10: fileglob((a*)^nb) against file (a^100).t; n = 3   0.00(0.00+0.00)   0.00(0.00+0.00) =
    0100.11: fileglob((a*)^nb) against file (a^100).t; n = 4   0.00(0.00+0.00)   0.01(0.00+0.00) +inf
    0100.12: fileglob((a*)^nb) against file (a^100).t; n = 5   0.00(0.00+0.00)   0.16(0.15+0.00) +inf
    0100.13: fileglob((a*)^nb) against file (a^100).t; n = 6   0.00(0.00+0.00)   2.75(2.73+0.00) +inf

Ævar Arnfjörð Bjarmason (2):
  perf: add function to setup a fresh test repo
  perf: add test showing exponential growth in path globbing

 t/perf/README            |  1 +
 t/perf/p0100-globbing.sh | 43 +++++++++++++++++++++++++++++++++++++++++++
 t/perf/perf-lib.sh       | 17 +++++++++++++----
 3 files changed, 57 insertions(+), 4 deletions(-)
 create mode 100755 t/perf/p0100-globbing.sh

-- 
2.11.0

[PATCH v3 1/2] perf: add function to setup a fresh test repo

[Ævar Arnfjörð Bjarmason]

Add a function to setup a fresh test repo via 'git init' to compliment
the existing functions to copy over a normal & large repo.

Some performance tests don't need any existing repository data at all
to be significant, e.g. tests which stress glob matches against single
pathological revisions or files, which I'm about to add in a
subsequent commit.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/perf/README      |  1 +
 t/perf/perf-lib.sh | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/t/perf/README b/t/perf/README
index 49ea4349be..de2fe15696 100644
--- a/t/perf/README
+++ b/t/perf/README
@@ -106,6 +106,7 @@ sources perf-lib.sh:
 
 After that you will want to use some of the following:
 
+	test_perf_fresh_repo    # sets up an empty repository
 	test_perf_default_repo  # sets up a "normal" repository
 	test_perf_large_repo    # sets up a "large" repository
 
diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index ab4b8b06ae..f51fc773e8 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -78,6 +78,10 @@ if test -z "$GIT_PERF_LARGE_REPO"; then
 	GIT_PERF_LARGE_REPO=$TEST_DIRECTORY/..
 fi
 
+test_perf_do_repo_symlink_config_ () {
+	test_have_prereq SYMLINKS || git config core.symlinks false
+}
+
 test_perf_create_repo_from () {
 	test "$#" = 2 ||
 	error "bug in the test script: not 2 parameters to test-create-repo"
@@ -102,15 +106,20 @@ test_perf_create_repo_from () {
 	) &&
 	(
 		cd "$repo" &&
-		"$MODERN_GIT" init -q && {
-			test_have_prereq SYMLINKS ||
-			git config core.symlinks false
-		} &&
+		"$MODERN_GIT" init -q &&
+		test_perf_do_repo_symlink_config_ &&
 		mv .git/hooks .git/hooks-disabled 2>/dev/null
 	) || error "failed to copy repository '$source' to '$repo'"
 }
 
 # call at least one of these to establish an appropriately-sized repository
+test_perf_fresh_repo () {
+	repo="${1:-$TRASH_DIRECTORY}"
+	"$MODERN_GIT" init -q "$repo" &&
+	cd "$repo" &&
+	test_perf_do_repo_symlink_config_
+}
+
 test_perf_default_repo () {
 	test_perf_create_repo_from "${1:-$TRASH_DIRECTORY}" "$GIT_PERF_REPO"
 }
-- 
2.11.0

[PATCH v3 2/2] perf: add test showing exponential growth in path globbing

[Ævar Arnfjörð Bjarmason]

Add a test showing that runtimes of the wildmatch() function used for
globbing in git grow exponentially in the face of some pathological
globs.

This issue affects both globs matching filenames via e.g. ls-files,
and globs matching refnames via e.g. for-each-ref.

As noted in the test description this is a test to see whether Git
suffers from the issue noted in an article Russ Cox posted today about
common bugs in various glob implementations:
https://research.swtch.com/glob

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/perf/p0100-globbing.sh | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100755 t/perf/p0100-globbing.sh

diff --git a/t/perf/p0100-globbing.sh b/t/perf/p0100-globbing.sh
new file mode 100755
index 0000000000..dd18a9ce2b
--- /dev/null
+++ b/t/perf/p0100-globbing.sh
@@ -0,0 +1,43 @@
+#!/bin/sh
+
+test_description="Tests pathological globbing performance
+
+Shows how Git's globbing performance performs when given the sort of
+pathological patterns described in at https://research.swtch.com/glob
+"
+
+. ./perf-lib.sh
+
+test_globs_big='10 25 50 75 100'
+test_globs_small='1 2 3 4 5 6'
+
+test_perf_fresh_repo
+
+test_expect_success 'setup' '
+	for i in $(test_seq 1 100)
+	do
+		printf "a" >>refname &&
+		for j in $(test_seq 1 $i)
+		do
+			printf "a*" >>refglob.$i
+		done &&
+		echo b >>refglob.$i
+	done &&
+	test_commit test $(cat refname).t "" $(cat refname).t
+'
+
+for i in $test_globs_small
+do
+	test_perf "refglob((a*)^nb) against tag (a^100).t; n = $i" '
+		git for-each-ref "refs/tags/$(cat refglob.'$i')b"
+	'
+done
+
+for i in $test_globs_small
+do
+	test_perf "fileglob((a*)^nb) against file (a^100).t; n = $i" '
+		git ls-files "$(cat refglob.'$i')b"
+	'
+done
+
+test_done
-- 
2.11.0

[PATCH v4 0/2] perf: show that wildmatch() regressed for pathological cases in v2.0

[Ævar Arnfjörð Bjarmason]

Fixes a brainfart in v3. I thought I'd fixed that subshell cd issue,
but turns out I didn't, actually fix that.

Ævar Arnfjörð Bjarmason (2):
  perf: add function to setup a fresh test repo
  perf: add test showing exponential growth in path globbing

 t/perf/README            |  1 +
 t/perf/p0100-globbing.sh | 43 +++++++++++++++++++++++++++++++++++++++++++
 t/perf/perf-lib.sh       | 19 +++++++++++++++----
 3 files changed, 59 insertions(+), 4 deletions(-)
 create mode 100755 t/perf/p0100-globbing.sh

-- 
2.11.0

Re: [PATCH v4 0/2] perf: show that wildmatch() regressed for pathological cases in v2.0

[Jonathan Nieder]

Ævar Arnfjörð Bjarmason wrote:

> Ævar Arnfjörð Bjarmason (2):
>   perf: add function to setup a fresh test repo
>   perf: add test showing exponential growth in path globbing
> 
>  t/perf/README            |  1 +
>  t/perf/p0100-globbing.sh | 43 +++++++++++++++++++++++++++++++++++++++++++
>  t/perf/perf-lib.sh       | 19 +++++++++++++++----
>  3 files changed, 59 insertions(+), 4 deletions(-)
>  create mode 100755 t/perf/p0100-globbing.sh

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>

Thanks.

[PATCH v4 1/2] perf: add function to setup a fresh test repo

[Ævar Arnfjörð Bjarmason]

Add a function to setup a fresh test repo via 'git init' to compliment
the existing functions to copy over a normal & large repo.

Some performance tests don't need any existing repository data at all
to be significant, e.g. tests which stress glob matches against single
pathological revisions or files, which I'm about to add in a
subsequent commit.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/perf/README      |  1 +
 t/perf/perf-lib.sh | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/t/perf/README b/t/perf/README
index 49ea4349be..de2fe15696 100644
--- a/t/perf/README
+++ b/t/perf/README
@@ -106,6 +106,7 @@ sources perf-lib.sh:
 
 After that you will want to use some of the following:
 
+	test_perf_fresh_repo    # sets up an empty repository
 	test_perf_default_repo  # sets up a "normal" repository
 	test_perf_large_repo    # sets up a "large" repository
 
diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index ab4b8b06ae..b6fc880395 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -78,6 +78,10 @@ if test -z "$GIT_PERF_LARGE_REPO"; then
 	GIT_PERF_LARGE_REPO=$TEST_DIRECTORY/..
 fi
 
+test_perf_do_repo_symlink_config_ () {
+	test_have_prereq SYMLINKS || git config core.symlinks false
+}
+
 test_perf_create_repo_from () {
 	test "$#" = 2 ||
 	error "bug in the test script: not 2 parameters to test-create-repo"
@@ -102,15 +106,22 @@ test_perf_create_repo_from () {
 	) &&
 	(
 		cd "$repo" &&
-		"$MODERN_GIT" init -q && {
-			test_have_prereq SYMLINKS ||
-			git config core.symlinks false
-		} &&
+		"$MODERN_GIT" init -q &&
+		test_perf_do_repo_symlink_config_ &&
 		mv .git/hooks .git/hooks-disabled 2>/dev/null
 	) || error "failed to copy repository '$source' to '$repo'"
 }
 
 # call at least one of these to establish an appropriately-sized repository
+test_perf_fresh_repo () {
+	repo="${1:-$TRASH_DIRECTORY}"
+	"$MODERN_GIT" init -q "$repo" &&
+	(
+		cd "$repo" &&
+		test_perf_do_repo_symlink_config_
+	)
+}
+
 test_perf_default_repo () {
 	test_perf_create_repo_from "${1:-$TRASH_DIRECTORY}" "$GIT_PERF_REPO"
 }
-- 
2.11.0

[PATCH v4 2/2] perf: add test showing exponential growth in path globbing

[Ævar Arnfjörð Bjarmason]

Add a test showing that runtimes of the wildmatch() function used for
globbing in git grow exponentially in the face of some pathological
globs.

This issue affects both globs matching filenames via e.g. ls-files,
and globs matching refnames via e.g. for-each-ref.

As noted in the test description this is a test to see whether Git
suffers from the issue noted in an article Russ Cox posted today about
common bugs in various glob implementations:
https://research.swtch.com/glob

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/perf/p0100-globbing.sh | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100755 t/perf/p0100-globbing.sh

diff --git a/t/perf/p0100-globbing.sh b/t/perf/p0100-globbing.sh
new file mode 100755
index 0000000000..dd18a9ce2b
--- /dev/null
+++ b/t/perf/p0100-globbing.sh
@@ -0,0 +1,43 @@
+#!/bin/sh
+
+test_description="Tests pathological globbing performance
+
+Shows how Git's globbing performance performs when given the sort of
+pathological patterns described in at https://research.swtch.com/glob
+"
+
+. ./perf-lib.sh
+
+test_globs_big='10 25 50 75 100'
+test_globs_small='1 2 3 4 5 6'
+
+test_perf_fresh_repo
+
+test_expect_success 'setup' '
+	for i in $(test_seq 1 100)
+	do
+		printf "a" >>refname &&
+		for j in $(test_seq 1 $i)
+		do
+			printf "a*" >>refglob.$i
+		done &&
+		echo b >>refglob.$i
+	done &&
+	test_commit test $(cat refname).t "" $(cat refname).t
+'
+
+for i in $test_globs_small
+do
+	test_perf "refglob((a*)^nb) against tag (a^100).t; n = $i" '
+		git for-each-ref "refs/tags/$(cat refglob.'$i')b"
+	'
+done
+
+for i in $test_globs_small
+do
+	test_perf "fileglob((a*)^nb) against file (a^100).t; n = $i" '
+		git ls-files "$(cat refglob.'$i')b"
+	'
+done
+
+test_done
-- 
2.11.0