hook: add -j/--jobs option to git hook run
Expose the parallel job count as a command-line flag so callers can request parallelism without relying only on the hook.jobs config. Add tests covering serial/parallel execution and TTY behaviour under -j1 vs -jN. Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Emily Shaffer committed
Apr 10, 2026 at 12:06 UTC
091d2dbeb452b2c8223c622b54e96ebd273b5a78
4 files changed
+170
-10
Documentation/git-hook.adoc
+21
-2
index 318c637bd8..46ea52db55 100644
--- a/Documentation/git-hook.adoc
+++ b/Documentation/git-hook.adoc
@@ -8,7 +8,8 @@ git-hook - Run git hooks
SYNOPSIS
--------
[verse]
-'git hook' run [--allow-unknown-hook-name] [--ignore-missing] [--to-stdin=<path>] <hook-name> [-- <hook-args>]
+'git hook' run [--allow-unknown-hook-name] [--ignore-missing] [--to-stdin=<path>] [(-j|--jobs) <n>]
+ <hook-name> [-- <hook-args>]
'git hook' list [--allow-unknown-hook-name] [-z] [--show-scope] <hook-name>
DESCRIPTION
@@ -147,6 +148,23 @@ OPTIONS
mirroring the output style of `git config --show-scope`. Traditional
hooks from the hookdir are unaffected.
+-j::
+--jobs::
+ Only valid for `run`.
++
+Specify how many hooks to run simultaneously. If this flag is not specified,
+the value of the `hook.jobs` config is used, see linkgit:git-config[1]. If
+neither is specified, defaults to 1 (serial execution).
++
+When greater than 1, it overrides the per-hook `hook.<friendly-name>.parallel`
+setting, allowing all hooks for the event to run concurrently, even if they
+are not individually marked as parallel.
++
+Some hooks always run sequentially regardless of this flag or the
+`hook.jobs` config, because git knows they cannot safely run in parallel:
+`applypatch-msg`, `pre-commit`, `prepare-commit-msg`, `commit-msg`,
+`post-commit`, `post-checkout`, and `push-to-checkout`.
+
WRAPPERS
--------
@@ -169,7 +187,8 @@ running:
git hook run --allow-unknown-hook-name mywrapper-start-tests \
# providing something to stdin
--stdin some-tempfile-123 \
- # execute hooks in serial
+ # execute multiple hooks in parallel
+ --jobs 3 \
# plus some arguments of your own...
-- \
--testname bar \
builtin/hook.c
+4
-1
index c0585587e5..bea0668b47 100644
--- a/builtin/hook.c
+++ b/builtin/hook.c
@@ -8,7 +8,8 @@
#include "parse-options.h"
#define BUILTIN_HOOK_RUN_USAGE \
- N_("git hook run [--allow-unknown-hook-name] [--ignore-missing] [--to-stdin=<path>] <hook-name> [-- <hook-args>]")
+ N_("git hook run [--allow-unknown-hook-name] [--ignore-missing] [--to-stdin=<path>] [(-j|--jobs) <n>]\n" \
+ "<hook-name> [-- <hook-args>]")
#define BUILTIN_HOOK_LIST_USAGE \
N_("git hook list [--allow-unknown-hook-name] [-z] [--show-scope] <hook-name>")
@@ -132,6 +133,8 @@ static int run(int argc, const char **argv, const char *prefix,
N_("silently ignore missing requested <hook-name>")),
OPT_STRING(0, "to-stdin", &opt.path_to_stdin, N_("path"),
N_("file to read into hooks' stdin")),
+ OPT_UNSIGNED('j', "jobs", &opt.jobs,
+ N_("run up to <n> hooks simultaneously")),
OPT_END(),
};
int ret;
hook.c
+17
index 25762b6c8d..c0b71322cf 100644
--- a/hook.c
+++ b/hook.c
@@ -568,6 +568,22 @@ static void merge_output_if_parallel(struct run_hooks_opt *options)
options->stdout_to_stderr = 1;
}
+static void warn_non_parallel_hooks_override(unsigned int jobs,
+ struct string_list *hook_list)
+{
+ /* Don't warn for hooks running sequentially. */
+ if (jobs == 1)
+ return;
+
+ for (size_t i = 0; i < hook_list->nr; i++) {
+ struct hook *h = hook_list->items[i].util;
+ if (h->kind == HOOK_CONFIGURED && !h->parallel)
+ warning(_("hook '%s' is not marked as parallel=true, "
+ "running in parallel anyway due to -j%u"),
+ h->u.configured.friendly_name, jobs);
+ }
+}
+
/* Determine how many jobs to use for hook execution. */
static unsigned int get_hook_jobs(struct repository *r,
struct run_hooks_opt *options,
@@ -611,6 +627,7 @@ static unsigned int get_hook_jobs(struct repository *r,
cleanup:
merge_output_if_parallel(options);
+ warn_non_parallel_hooks_override(options->jobs, hook_list);
return options->jobs;
}
t/t1800-hook.sh
+128
-7
index 63fa25bca2..aa37a5181a 100755
--- a/t/t1800-hook.sh
+++ b/t/t1800-hook.sh
@@ -268,10 +268,20 @@ test_expect_success 'git -c core.hooksPath=<PATH> hook run' '
'
test_hook_tty () {
- cat >expect <<-\EOF
- STDOUT TTY
- STDERR TTY
- EOF
+ expect_tty=$1
+ shift
+
+ if test "$expect_tty" != "no_tty"; then
+ cat >expect <<-\EOF
+ STDOUT TTY
+ STDERR TTY
+ EOF
+ else
+ cat >expect <<-\EOF
+ STDOUT NO TTY
+ STDERR NO TTY
+ EOF
+ fi
test_when_finished "rm -rf repo" &&
git init repo &&
@@ -289,12 +299,21 @@ test_hook_tty () {
test_cmp expect repo/actual
}
-test_expect_success TTY 'git hook run: stdout and stderr are connected to a TTY' '
- test_hook_tty hook run pre-commit
+test_expect_success TTY 'git hook run -j1: stdout and stderr are connected to a TTY' '
+ # hooks running sequentially (-j1) are always connected to the tty for
+ # optimum real-time performance.
+ test_hook_tty tty hook run -j1 pre-commit
+'
+
+test_expect_success TTY 'git hook run -jN: stdout and stderr are not connected to a TTY' '
+ # Hooks are not connected to the tty when run in parallel, instead they
+ # output to a pipe through which run-command collects and de-interlaces
+ # their outputs, which then gets passed either to the tty or a sideband.
+ test_hook_tty no_tty hook run -j2 pre-commit
'
test_expect_success TTY 'git commit: stdout and stderr are connected to a TTY' '
- test_hook_tty commit -m"B.new"
+ test_hook_tty tty commit -m"B.new"
'
test_expect_success 'git hook list orders by config order' '
@@ -709,6 +728,108 @@ test_expect_success 'server push-to-checkout hook expects stdout redirected to s
check_stdout_merged_to_stderr push-to-checkout
'
+test_expect_success 'parallel hook output is not interleaved' '
+ test_when_finished "rm -rf .git/hooks" &&
+
+ write_script .git/hooks/test-hook <<-EOF &&
+ echo "Hook 1 Start"
+ sleep 1
+ echo "Hook 1 End"
+ EOF
+
+ test_config hook.hook-2.event test-hook &&
+ test_config hook.hook-2.command \
+ "echo \"Hook 2 Start\"; sleep 2; echo \"Hook 2 End\"" &&
+ test_config hook.hook-2.parallel true &&
+ test_config hook.hook-3.event test-hook &&
+ test_config hook.hook-3.command \
+ "echo \"Hook 3 Start\"; sleep 3; echo \"Hook 3 End\"" &&
+ test_config hook.hook-3.parallel true &&
+
+ git hook run --allow-unknown-hook-name -j3 test-hook >out 2>err.parallel &&
+
+ # Verify Hook 1 output is grouped
+ sed -n "/Hook 1 Start/,/Hook 1 End/p" err.parallel >hook1_out &&
+ test_line_count = 2 hook1_out &&
+
+ # Verify Hook 2 output is grouped
+ sed -n "/Hook 2 Start/,/Hook 2 End/p" err.parallel >hook2_out &&
+ test_line_count = 2 hook2_out &&
+
+ # Verify Hook 3 output is grouped
+ sed -n "/Hook 3 Start/,/Hook 3 End/p" err.parallel >hook3_out &&
+ test_line_count = 2 hook3_out
+'
+
+test_expect_success 'git hook run -j1 runs hooks in series' '
+ test_when_finished "rm -rf .git/hooks" &&
+
+ test_config hook.series-1.event "test-hook" &&
+ test_config hook.series-1.command "echo 1" --add &&
+ test_config hook.series-2.event "test-hook" &&
+ test_config hook.series-2.command "echo 2" --add &&
+
+ mkdir -p .git/hooks &&
+ write_script .git/hooks/test-hook <<-EOF &&
+ echo 3
+ EOF
+
+ cat >expected <<-\EOF &&
+ 1
+ 2
+ 3
+ EOF
+
+ git hook run --allow-unknown-hook-name -j1 test-hook 2>actual &&
+ test_cmp expected actual
+'
+
+test_expect_success 'git hook run -j2 runs hooks in parallel' '
+ test_when_finished "rm -f sentinel.started sentinel.done hook.order" &&
+ test_when_finished "rm -rf .git/hooks" &&
+
+ mkdir -p .git/hooks &&
+ write_sentinel_hook .git/hooks/test-hook &&
+
+ test_config hook.hook-2.event test-hook &&
+ test_config hook.hook-2.command \
+ "$(sentinel_detector sentinel hook.order)" &&
+ test_config hook.hook-2.parallel true &&
+
+ git hook run --allow-unknown-hook-name -j2 test-hook >out 2>err &&
+ echo parallel >expect &&
+ test_cmp expect hook.order
+'
+
+test_expect_success 'git hook run -j2 overrides parallel=false' '
+ test_when_finished "rm -f sentinel.started sentinel.done hook.order" &&
+ test_config hook.hook-1.event test-hook &&
+ test_config hook.hook-1.command \
+ "touch sentinel.started; sleep 2; touch sentinel.done" &&
+ # hook-1 intentionally has no parallel=true
+ test_config hook.hook-2.event test-hook &&
+ test_config hook.hook-2.command \
+ "$(sentinel_detector sentinel hook.order)" &&
+ # hook-2 also has no parallel=true
+
+ # -j2 overrides parallel=false; hooks run in parallel with a warning.
+ git hook run --allow-unknown-hook-name -j2 test-hook >out 2>err &&
+ echo parallel >expect &&
+ test_cmp expect hook.order
+'
+
+test_expect_success 'git hook run -j2 warns for hooks not marked parallel=true' '
+ test_config hook.hook-1.event test-hook &&
+ test_config hook.hook-1.command "true" &&
+ test_config hook.hook-2.event test-hook &&
+ test_config hook.hook-2.command "true" &&
+ # neither hook has parallel=true
+
+ git hook run --allow-unknown-hook-name -j2 test-hook >out 2>err &&
+ grep "hook .hook-1. is not marked as parallel=true" err &&
+ grep "hook .hook-2. is not marked as parallel=true" err
+'
+
test_expect_success 'hook.jobs=1 config runs hooks in series' '
test_when_finished "rm -f sentinel.started sentinel.done hook.order" &&