hook: allow hook.jobs=-1 to use all available CPU cores
Allow -1 as a value for hook.jobs, hook.<event>.jobs, and the -j CLI flag to mean "use as many jobs as there are CPU cores", matching the convention used by fetch.parallel and other Git subsystems. The value is resolved to online_cpus() at parse time so the rest of the code always works with a positive resolved count. Other non-positive values (0, -2, etc) are rejected with a warning (config) or die (CLI). Suggested-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Adrian Ratiu committed
Apr 10, 2026 at 12:06 UTC
495b7d54dc006556548e2fd3ca15c4f533917329
4 files changed
+108
-20
Documentation/config/hook.adoc
+3
-1
@@ -58,7 +58,8 @@ hook.<event>.jobs::
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hook event (e.g. `hook.post-receive.jobs = 4`). Overrides `hook.jobs`
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for this specific event. The same parallelism restrictions apply: this
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setting has no effect unless all configured hooks for the event have
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- `hook.<friendly-name>.parallel` set to `true`. Must be a positive int,
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+ `hook.<friendly-name>.parallel` set to `true`. Set to `-1` to use the
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+ number of available CPU cores. Must be a positive integer or `-1`;
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zero is rejected with a warning. See linkgit:git-hook[1].
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+
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Note on naming: although this key resembles `hook.<friendly-name>.*`
@@ -74,6 +75,7 @@ valid event name when setting `hook.<event>.jobs`.
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hook.jobs::
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Specifies how many hooks can be run simultaneously during parallelized
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hook execution. If unspecified, defaults to 1 (serial execution).
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+ Set to `-1` to use the number of available CPU cores.
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Can be overridden on a per-event basis with `hook.<event>.jobs`.
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Some hooks always run sequentially regardless of this setting because
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they operate on shared data and cannot safely be parallelized:
builtin/hook.c
+13
-2
@@ -5,6 +5,7 @@
5
#include "gettext.h"
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#include "hook.h"
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#include "parse-options.h"
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+#include "thread-utils.h"
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#define BUILTIN_HOOK_RUN_USAGE \
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N_("git hook run [--allow-unknown-hook-name] [--ignore-missing] [--to-stdin=<path>] [(-j|--jobs) <n>]\n" \
@@ -123,6 +124,7 @@ static int run(int argc, const char **argv, const char *prefix,
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struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
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int ignore_missing = 0;
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int allow_unknown = 0;
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+ int jobs = 0;
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const char *hook_name;
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struct option run_options[] = {
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OPT_BOOL(0, "allow-unknown-hook-name", &allow_unknown,
@@ -131,8 +133,8 @@ static int run(int argc, const char **argv, const char *prefix,
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N_("silently ignore missing requested <hook-name>")),
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OPT_STRING(0, "to-stdin", &opt.path_to_stdin, N_("path"),
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N_("file to read into hooks' stdin")),
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- OPT_UNSIGNED('j', "jobs", &opt.jobs,
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- N_("run up to <n> hooks simultaneously")),
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+ OPT_INTEGER('j', "jobs", &jobs,
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+ N_("run up to <n> hooks simultaneously (-1 for CPU count)")),
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OPT_END(),
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};
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int ret;
@@ -141,6 +143,15 @@ static int run(int argc, const char **argv, const char *prefix,
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builtin_hook_run_usage,
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PARSE_OPT_KEEP_DASHDASH);
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+ if (jobs == -1)
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+ opt.jobs = online_cpus();
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+ else if (jobs < 0)
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+ die(_("invalid value for -j: %d"
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+ " (use -1 for CPU count or a"
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+ " positive integer)"), jobs);
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+ else
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+ opt.jobs = jobs;
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+
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if (!argc)
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goto usage;
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hook.c
+43
-17
@@ -12,6 +12,7 @@
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#include "setup.h"
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#include "strbuf.h"
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#include "strmap.h"
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+#include "thread-utils.h"
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17
bool is_known_hook(const char *name)
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{
@@ -165,13 +166,17 @@ static int hook_config_lookup_all(const char *key, const char *value,
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/* Handle plain hook.<key> entries that have no hook name component. */
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if (!name) {
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if (!strcmp(subkey, "jobs") && value) {
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- unsigned int v;
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- if (!git_parse_uint(value, &v))
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- warning(_("hook.jobs must be a positive integer, ignoring: '%s'"), value);
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- else if (!v)
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- warning(_("hook.jobs must be positive, ignoring: 0"));
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- else
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+ int v;
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+ if (!git_parse_int(value, &v))
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+ warning(_("hook.jobs must be an integer, ignoring: '%s'"), value);
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+ else if (v == -1)
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+ data->jobs = online_cpus();
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+ else if (v > 0)
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data->jobs = v;
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+ else
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+ warning(_("hook.jobs must be a positive integer"
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+ " or -1, ignoring: '%s'"),
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+ value);
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}
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return 0;
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}
@@ -259,17 +264,21 @@ static int hook_config_lookup_all(const char *key, const char *value,
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" ignoring: '%s'"),
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hook_name, value);
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} else if (!strcmp(subkey, "jobs")) {
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- unsigned int v;
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- if (!git_parse_uint(value, &v))
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- warning(_("hook.%s.jobs must be a positive integer,"
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+ int v;
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+ if (!git_parse_int(value, &v))
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+ warning(_("hook.%s.jobs must be an integer,"
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" ignoring: '%s'"),
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hook_name, value);
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- else if (!v)
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- warning(_("hook.%s.jobs must be positive,"
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- " ignoring: 0"), hook_name);
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- else
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+ else if (v == -1)
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+ strmap_put(&data->event_jobs, hook_name,
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+ (void *)(uintptr_t)online_cpus());
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+ else if (v > 0)
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strmap_put(&data->event_jobs, hook_name,
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(void *)(uintptr_t)v);
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+ else
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+ warning(_("hook.%s.jobs must be a positive"
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+ " integer or -1, ignoring: '%s'"),
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+ hook_name, value);
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}
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free(hook_name);
@@ -688,6 +697,25 @@ static void warn_non_parallel_hooks_override(unsigned int jobs,
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}
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}
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+/* Resolve a hook.jobs config key, handling -1 as online_cpus(). */
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+static void resolve_hook_config_jobs(struct repository *r,
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+ const char *key,
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+ unsigned int *jobs)
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+{
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+ int v;
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+
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+ if (repo_config_get_int(r, key, &v))
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+ return;
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+
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+ if (v == -1)
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+ *jobs = online_cpus();
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+ else if (v > 0)
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+ *jobs = v;
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+ else
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+ warning(_("%s must be a positive integer or -1,"
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+ " ignoring: %d"), key, v);
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+}
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+
719
/* Determine how many jobs to use for hook execution. */
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static unsigned int get_hook_jobs(struct repository *r,
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struct run_hooks_opt *options,
@@ -721,14 +749,12 @@ static unsigned int get_hook_jobs(struct repository *r,
749
if (event_jobs)
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options->jobs = (unsigned int)(uintptr_t)event_jobs;
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} else {
724
- unsigned int event_jobs;
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char *key;
753
727
- repo_config_get_uint(r, "hook.jobs", &options->jobs);
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+ resolve_hook_config_jobs(r, "hook.jobs", &options->jobs);
755
756
key = xstrfmt("hook.%s.jobs", hook_name);
730
- if (!repo_config_get_uint(r, key, &event_jobs) && event_jobs)
731
- options->jobs = event_jobs;
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+ resolve_hook_config_jobs(r, key, &options->jobs);
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free(key);
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}
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}
t/t1800-hook.sh
+49
@@ -1058,6 +1058,55 @@ test_expect_success 'hook.<event>.jobs does not warn for a real event name' '
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test_grep ! "friendly-name" err
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'
1060
1061
+test_expect_success 'hook.jobs=-1 resolves to online_cpus()' '
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+ test_config hook.hook-1.event test-hook &&
1063
+ test_config hook.hook-1.command "true" &&
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+ test_config hook.hook-1.parallel true &&
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+
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+ test_config hook.jobs -1 &&
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+
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+ cpus=$(test-tool online-cpus) &&
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+ GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
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+ git hook run --allow-unknown-hook-name test-hook >out 2>err &&
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+ grep "\"region_enter\".*\"hook\".*\"test-hook\".*\"max:$cpus\"" trace.txt
1072
+'
1073
+
1074
+test_expect_success 'hook.<event>.jobs=-1 resolves to online_cpus()' '
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+ test_config hook.hook-1.event test-hook &&
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+ test_config hook.hook-1.command "true" &&
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+ test_config hook.hook-1.parallel true &&
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+
1079
+ test_config hook.test-hook.jobs -1 &&
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+
1081
+ cpus=$(test-tool online-cpus) &&
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+ GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
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+ git hook run --allow-unknown-hook-name test-hook >out 2>err &&
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+ grep "\"region_enter\".*\"hook\".*\"test-hook\".*\"max:$cpus\"" trace.txt
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+'
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+
1087
+test_expect_success 'git hook run -j-1 resolves to online_cpus()' '
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+ test_config hook.hook-1.event test-hook &&
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+ test_config hook.hook-1.command "true" &&
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+ test_config hook.hook-1.parallel true &&
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+
1092
+ cpus=$(test-tool online-cpus) &&
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+ GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
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+ git hook run --allow-unknown-hook-name -j-1 test-hook >out 2>err &&
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+ grep "\"region_enter\".*\"hook\".*\"test-hook\".*\"max:$cpus\"" trace.txt
1096
+'
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+
1098
+test_expect_success 'hook.jobs rejects values less than -1' '
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+ test_config hook.jobs -2 &&
1100
+ git hook run --allow-unknown-hook-name --ignore-missing test-hook >out 2>err &&
1101
+ test_grep "hook.jobs must be a positive integer or -1" err
1102
+'
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+
1104
+test_expect_success 'hook.<event>.jobs rejects values less than -1' '
1105
+ test_config hook.test-hook.jobs -5 &&
1106
+ git hook run --allow-unknown-hook-name --ignore-missing test-hook >out 2>err &&
1107
+ test_grep "hook.test-hook.jobs must be a positive integer or -1" err
1108
+'
1109
+
1110
test_expect_success 'hook.<event>.enabled=false skips all hooks for event' '
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test_config hook.hook-1.event test-hook &&
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test_config hook.hook-1.command "echo ran" &&