[PATCHv7 0/8] Expose submodule parallelism to the user

[PATCHv7 0/8] Expose submodule parallelism to the user

[Stefan Beller]

This is a resend of sb/submodule-parallel-update and is available at github[1] as well.
It applies on top of sb/submodule-parallel-fetch

What does it do?
---
This series should finish the on going efforts of parallelizing
submodule network traffic. The patches contain tests for
  clone
  fetch
  submodule update
to use the actual parallelism both via command line as well as a
configured option. I decided to go with "submodule.fetchJobs" for
all three for now.

What changed to v5,6?
---
No major changes, I just made it compile again as the order of parameters
to the parallel processing engine changed.

Thanks,
Stefan

[1] https://github.com/stefanbeller/git/tree/submodule-parallel-update-v7

Stefan Beller (8):
  submodule-config: keep update strategy around
  submodule-config: drop check against NULL
  submodule-config: remove name_and_item_from_var
  submodule-config: introduce parse_generic_submodule_config
  fetching submodules: respect `submodule.fetchJobs` config option
  git submodule update: have a dedicated helper for cloning
  submodule update: expose parallelism to the user
  clone: allow an explicit argument for parallel submodule clones

 Documentation/config.txt        |   7 ++
 Documentation/git-clone.txt     |   6 +-
 Documentation/git-submodule.txt |   7 +-
 builtin/clone.c                 |  19 +++-
 builtin/fetch.c                 |   2 +-
 builtin/submodule--helper.c     | 239 ++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh                |  54 ++++-----
 submodule-config.c              | 109 +++++++++++-------
 submodule-config.h              |   3 +
 submodule.c                     |   5 +
 t/t5526-fetch-submodules.sh     |  14 +++
 t/t7400-submodule-basic.sh      |   4 +-
 t/t7406-submodule-update.sh     |  27 +++++
 13 files changed, 413 insertions(+), 83 deletions(-)

-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 1/8] submodule-config: keep update strategy around

[Stefan Beller]

We need the submodule update strategies in a later patch.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 submodule-config.c | 11 +++++++++++
 submodule-config.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/submodule-config.c b/submodule-config.c
index afe0ea8..4239b0e 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -194,6 +194,7 @@ static struct submodule *lookup_or_create_by_name(struct submodule_cache *cache,
 
 	submodule->path = NULL;
 	submodule->url = NULL;
+	submodule->update = NULL;
 	submodule->fetch_recurse = RECURSE_SUBMODULES_NONE;
 	submodule->ignore = NULL;
 
@@ -311,6 +312,16 @@ static int parse_config(const char *var, const char *value, void *data)
 			free((void *) submodule->url);
 			submodule->url = xstrdup(value);
 		}
+	} else if (!strcmp(item.buf, "update")) {
+		if (!value)
+			ret = config_error_nonbool(var);
+		else if (!me->overwrite && submodule->update != NULL)
+			warn_multiple_config(me->commit_sha1, submodule->name,
+					     "update");
+		else {
+			free((void *) submodule->update);
+			submodule->update = xstrdup(value);
+		}
 	}
 
 	strbuf_release(&name);
diff --git a/submodule-config.h b/submodule-config.h
index 9061e4e..f9e2a29 100644
--- a/submodule-config.h
+++ b/submodule-config.h
@@ -14,6 +14,7 @@ struct submodule {
 	const char *url;
 	int fetch_recurse;
 	const char *ignore;
+	const char *update;
 	/* the sha1 blob id of the responsible .gitmodules file */
 	unsigned char gitmodules_sha1[20];
 };
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 2/8] submodule-config: drop check against NULL

[Stefan Beller]

Adhere to the common coding style of Git and not check explicitly
for NULL throughout the file. There are still other occurrences in the
code base but that is usually inside of conditions with side effects.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 submodule-config.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/submodule-config.c b/submodule-config.c
index 4239b0e..6d01941 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -265,7 +265,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	if (!strcmp(item.buf, "path")) {
 		if (!value)
 			ret = config_error_nonbool(var);
-		else if (!me->overwrite && submodule->path != NULL)
+		else if (!me->overwrite && submodule->path)
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					"path");
 		else {
@@ -289,7 +289,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	} else if (!strcmp(item.buf, "ignore")) {
 		if (!value)
 			ret = config_error_nonbool(var);
-		else if (!me->overwrite && submodule->ignore != NULL)
+		else if (!me->overwrite && submodule->ignore)
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					"ignore");
 		else if (strcmp(value, "untracked") &&
@@ -305,7 +305,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	} else if (!strcmp(item.buf, "url")) {
 		if (!value) {
 			ret = config_error_nonbool(var);
-		} else if (!me->overwrite && submodule->url != NULL) {
+		} else if (!me->overwrite && submodule->url) {
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					"url");
 		} else {
@@ -315,7 +315,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	} else if (!strcmp(item.buf, "update")) {
 		if (!value)
 			ret = config_error_nonbool(var);
-		else if (!me->overwrite && submodule->update != NULL)
+		else if (!me->overwrite && submodule->update)
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					     "update");
 		else {
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 3/8] submodule-config: remove name_and_item_from_var

[Stefan Beller]

`name_and_item_from_var` does not provide the proper abstraction
we need here in a later patch.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 submodule-config.c | 48 ++++++++++++++++--------------------------------
 1 file changed, 16 insertions(+), 32 deletions(-)

diff --git a/submodule-config.c b/submodule-config.c
index 6d01941..b826841 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -161,31 +161,17 @@ static struct submodule *cache_lookup_name(struct submodule_cache *cache,
 	return NULL;
 }
 
-static int name_and_item_from_var(const char *var, struct strbuf *name,
-				  struct strbuf *item)
-{
-	const char *subsection, *key;
-	int subsection_len, parse;
-	parse = parse_config_key(var, "submodule", &subsection,
-			&subsection_len, &key);
-	if (parse < 0 || !subsection)
-		return 0;
-
-	strbuf_add(name, subsection, subsection_len);
-	strbuf_addstr(item, key);
-
-	return 1;
-}
-
 static struct submodule *lookup_or_create_by_name(struct submodule_cache *cache,
-		const unsigned char *gitmodules_sha1, const char *name)
+						  const unsigned char *gitmodules_sha1,
+						  const char *name_ptr, int name_len)
 {
 	struct submodule *submodule;
 	struct strbuf name_buf = STRBUF_INIT;
+	char *name = xmemdupz(name_ptr, name_len);
 
 	submodule = cache_lookup_name(cache, gitmodules_sha1, name);
 	if (submodule)
-		return submodule;
+		goto out;
 
 	submodule = xmalloc(sizeof(*submodule));
 
@@ -201,7 +187,8 @@ static struct submodule *lookup_or_create_by_name(struct submodule_cache *cache,
 	hashcpy(submodule->gitmodules_sha1, gitmodules_sha1);
 
 	cache_add(cache, submodule);
-
+out:
+	free(name);
 	return submodule;
 }
 
@@ -251,18 +238,18 @@ static int parse_config(const char *var, const char *value, void *data)
 {
 	struct parse_config_parameter *me = data;
 	struct submodule *submodule;
-	struct strbuf name = STRBUF_INIT, item = STRBUF_INIT;
-	int ret = 0;
+	int subsection_len, ret = 0;
+	const char *subsection, *key;
 
-	/* this also ensures that we only parse submodule entries */
-	if (!name_and_item_from_var(var, &name, &item))
+	if (parse_config_key(var, "submodule", &subsection,
+			     &subsection_len, &key) < 0 || !subsection_len)
 		return 0;
 
 	submodule = lookup_or_create_by_name(me->cache,
 					     me->gitmodules_sha1,
-					     name.buf);
+					     subsection, subsection_len);
 
-	if (!strcmp(item.buf, "path")) {
+	if (!strcmp(key, "path")) {
 		if (!value)
 			ret = config_error_nonbool(var);
 		else if (!me->overwrite && submodule->path)
@@ -275,7 +262,7 @@ static int parse_config(const char *var, const char *value, void *data)
 			submodule->path = xstrdup(value);
 			cache_put_path(me->cache, submodule);
 		}
-	} else if (!strcmp(item.buf, "fetchrecursesubmodules")) {
+	} else if (!strcmp(key, "fetchrecursesubmodules")) {
 		/* when parsing worktree configurations we can die early */
 		int die_on_error = is_null_sha1(me->gitmodules_sha1);
 		if (!me->overwrite &&
@@ -286,7 +273,7 @@ static int parse_config(const char *var, const char *value, void *data)
 			submodule->fetch_recurse = parse_fetch_recurse(
 								var, value,
 								die_on_error);
-	} else if (!strcmp(item.buf, "ignore")) {
+	} else if (!strcmp(key, "ignore")) {
 		if (!value)
 			ret = config_error_nonbool(var);
 		else if (!me->overwrite && submodule->ignore)
@@ -302,7 +289,7 @@ static int parse_config(const char *var, const char *value, void *data)
 			free((void *) submodule->ignore);
 			submodule->ignore = xstrdup(value);
 		}
-	} else if (!strcmp(item.buf, "url")) {
+	} else if (!strcmp(key, "url")) {
 		if (!value) {
 			ret = config_error_nonbool(var);
 		} else if (!me->overwrite && submodule->url) {
@@ -312,7 +299,7 @@ static int parse_config(const char *var, const char *value, void *data)
 			free((void *) submodule->url);
 			submodule->url = xstrdup(value);
 		}
-	} else if (!strcmp(item.buf, "update")) {
+	} else if (!strcmp(key, "update")) {
 		if (!value)
 			ret = config_error_nonbool(var);
 		else if (!me->overwrite && submodule->update)
@@ -324,9 +311,6 @@ static int parse_config(const char *var, const char *value, void *data)
 		}
 	}
 
-	strbuf_release(&name);
-	strbuf_release(&item);
-
 	return ret;
 }
 
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 4/8] submodule-config: introduce parse_generic_submodule_config

[Stefan Beller]

This rewrites parse_config to distinguish between configs specific to
one submodule and configs which apply generically to all submodules.
We do not have generic submodule configs yet, but the next patch will
introduce "submodule.fetchJobs".

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 submodule-config.c | 41 ++++++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 9 deletions(-)

diff --git a/submodule-config.c b/submodule-config.c
index b826841..29e21b2 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -234,17 +234,22 @@ struct parse_config_parameter {
 	int overwrite;
 };
 
-static int parse_config(const char *var, const char *value, void *data)
+static int parse_generic_submodule_config(const char *key,
+					  const char *var,
+					  const char *value,
+					  struct parse_config_parameter *me)
 {
-	struct parse_config_parameter *me = data;
-	struct submodule *submodule;
-	int subsection_len, ret = 0;
-	const char *subsection, *key;
-
-	if (parse_config_key(var, "submodule", &subsection,
-			     &subsection_len, &key) < 0 || !subsection_len)
-		return 0;
+	return 0;
+}
 
+static int parse_specific_submodule_config(const char *subsection, int subsection_len,
+					   const char *key,
+					   const char *var,
+					   const char *value,
+					   struct parse_config_parameter *me)
+{
+	int ret = 0;
+	struct submodule *submodule;
 	submodule = lookup_or_create_by_name(me->cache,
 					     me->gitmodules_sha1,
 					     subsection, subsection_len);
@@ -314,6 +319,24 @@ static int parse_config(const char *var, const char *value, void *data)
 	return ret;
 }
 
+static int parse_config(const char *var, const char *value, void *data)
+{
+	struct parse_config_parameter *me = data;
+	int subsection_len;
+	const char *subsection, *key;
+
+	if (parse_config_key(var, "submodule", &subsection,
+			     &subsection_len, &key) < 0)
+		return 0;
+
+	if (!subsection_len)
+		return parse_generic_submodule_config(key, var, value, me);
+	else
+		return parse_specific_submodule_config(subsection,
+						       subsection_len, key,
+						       var, value, me);
+}
+
 static int gitmodule_sha1_from_commit(const unsigned char *commit_sha1,
 				      unsigned char *gitmodules_sha1)
 {
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 5/8] fetching submodules: respect `submodule.fetchJobs` config option

[Stefan Beller]

This allows to configure fetching and updating in parallel
without having the command line option.

This moved the responsibility to determine how many parallel processes
to start from builtin/fetch to submodule.c as we need a way to communicate
"The user did not specify the number of parallel processes in the command
line options" in the builtin fetch. The submodule code takes care of
the precedence (CLI > config > default)

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 Documentation/config.txt    |  7 +++++++
 builtin/fetch.c             |  2 +-
 submodule-config.c          | 15 +++++++++++++++
 submodule-config.h          |  2 ++
 submodule.c                 |  5 +++++
 t/t5526-fetch-submodules.sh | 14 ++++++++++++++
 6 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 2d06b11..eda3276 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2646,6 +2646,13 @@ submodule.<name>.ignore::
 	"--ignore-submodules" option. The 'git submodule' commands are not
 	affected by this setting.
 
+submodule.fetchJobs::
+	This is used to determine how many submodules will be
+	fetched/cloned at the same time. Specifying a positive integer
+	allows up to that number of submodules being fetched in parallel.
+	This is used in fetch and clone operations only. A value of 0 will
+	give some reasonable configuration. It defaults to 1.
+
 tag.sort::
 	This variable controls the sort ordering of tags when displayed by
 	linkgit:git-tag[1]. Without the "--sort=<value>" option provided, the
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 586840d..5aa1c2d 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -37,7 +37,7 @@ static int prune = -1; /* unspecified */
 static int all, append, dry_run, force, keep, multiple, update_head_ok, verbosity;
 static int progress = -1, recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
 static int tags = TAGS_DEFAULT, unshallow, update_shallow;
-static int max_children = 1;
+static int max_children = -1;
 static const char *depth;
 static const char *upload_pack;
 static struct strbuf default_rla = STRBUF_INIT;
diff --git a/submodule-config.c b/submodule-config.c
index 29e21b2..a32259e 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -32,6 +32,7 @@ enum lookup_type {
 
 static struct submodule_cache cache;
 static int is_cache_init;
+static int parallel_jobs = -1;
 
 static int config_path_cmp(const struct submodule_entry *a,
 			   const struct submodule_entry *b,
@@ -239,6 +240,15 @@ static int parse_generic_submodule_config(const char *key,
 					  const char *value,
 					  struct parse_config_parameter *me)
 {
+	if (!strcmp(key, "fetchjobs")) {
+		parallel_jobs = strtol(value, NULL, 10);
+		if (parallel_jobs < 0) {
+			warning("submodule.fetchJobs not allowed to be negative.");
+			parallel_jobs = 1;
+			return 1;
+		}
+	}
+
 	return 0;
 }
 
@@ -482,3 +492,8 @@ void submodule_free(void)
 	cache_free(&cache);
 	is_cache_init = 0;
 }
+
+int config_parallel_submodules(void)
+{
+	return parallel_jobs;
+}
diff --git a/submodule-config.h b/submodule-config.h
index f9e2a29..d9bbf9a 100644
--- a/submodule-config.h
+++ b/submodule-config.h
@@ -27,4 +27,6 @@ const struct submodule *submodule_from_path(const unsigned char *commit_sha1,
 		const char *path);
 void submodule_free(void);
 
+int config_parallel_submodules(void);
+
 #endif /* SUBMODULE_CONFIG_H */
diff --git a/submodule.c b/submodule.c
index b83939c..eb7d54b 100644
--- a/submodule.c
+++ b/submodule.c
@@ -751,6 +751,11 @@ int fetch_populated_submodules(const struct argv_array *options,
 	argv_array_push(&spf.args, "--recurse-submodules-default");
 	/* default value, "--submodule-prefix" and its value are added later */
 
+	if (max_parallel_jobs < 0)
+		max_parallel_jobs = config_parallel_submodules();
+	if (max_parallel_jobs < 0)
+		max_parallel_jobs = 1;
+
 	calculate_changed_submodule_paths();
 	run_processes_parallel(max_parallel_jobs,
 			       get_next_submodule,
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 1241146..954d0e4 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -471,4 +471,18 @@ test_expect_success "don't fetch submodule when newly recorded commits are alrea
 	test_i18ncmp expect.err actual.err
 '
 
+test_expect_success 'fetching submodules respects parallel settings' '
+	git config fetch.recurseSubmodules true &&
+	(
+		cd downstream &&
+		GIT_TRACE=$(pwd)/trace.out git fetch --jobs 7 &&
+		grep "7 tasks" trace.out &&
+		git config submodule.fetchJobs 8 &&
+		GIT_TRACE=$(pwd)/trace.out git fetch &&
+		grep "8 tasks" trace.out &&
+		GIT_TRACE=$(pwd)/trace.out git fetch --jobs 9 &&
+		grep "9 tasks" trace.out
+	)
+'
+
 test_done
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 6/8] git submodule update: have a dedicated helper for cloning

[Stefan Beller]

This introduces a new helper function in git submodule--helper
which takes care of cloning all submodules, which we want to
parallelize eventually.

Some tests (such as empty URL, update_mode=none) are required in the
helper to make the decision for cloning. These checks have been
moved into the C function as well (no need to repeat them in the
shell script).

As we can only access the stderr channel from within the parallel
processing engine, we need to reroute the error message for
specified but initialized submodules to stderr. As it is an error
message, this should have gone to stderr in the first place, so it
is a bug fix along the way.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/submodule--helper.c | 229 ++++++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh            |  45 +++------
 t/t7400-submodule-basic.sh  |   4 +-
 3 files changed, 242 insertions(+), 36 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index f4c3eff..9441f20 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -255,6 +255,234 @@ static int module_clone(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+static int git_submodule_config(const char *var, const char *value, void *cb)
+{
+	return parse_submodule_config_option(var, value);
+}
+
+struct submodule_update_clone {
+	/* states */
+	int count;
+	int print_unmatched;
+	/* configuration */
+	int quiet;
+	const char *reference;
+	const char *depth;
+	const char *update;
+	const char *recursive_prefix;
+	const char *prefix;
+	struct module_list list;
+	struct string_list projectlines;
+	struct pathspec pathspec;
+};
+#define SUBMODULE_UPDATE_CLONE_INIT {0, 0, 0, NULL, NULL, NULL, NULL, NULL, MODULE_LIST_INIT, STRING_LIST_INIT_DUP}
+
+static void fill_clone_command(struct child_process *cp, int quiet,
+			       const char *prefix, const char *path,
+			       const char *name, const char *url,
+			       const char *reference, const char *depth)
+{
+	cp->git_cmd = 1;
+	cp->no_stdin = 1;
+	cp->stdout_to_stderr = 1;
+	cp->err = -1;
+	argv_array_push(&cp->args, "submodule--helper");
+	argv_array_push(&cp->args, "clone");
+	if (quiet)
+		argv_array_push(&cp->args, "--quiet");
+
+	if (prefix)
+		argv_array_pushl(&cp->args, "--prefix", prefix, NULL);
+
+	argv_array_pushl(&cp->args, "--path", path, NULL);
+	argv_array_pushl(&cp->args, "--name", name, NULL);
+	argv_array_pushl(&cp->args, "--url", url, NULL);
+	if (reference)
+		argv_array_push(&cp->args, reference);
+	if (depth)
+		argv_array_push(&cp->args, depth);
+}
+
+static int update_clone_get_next_task(struct child_process *cp,
+				      struct strbuf *err,
+				      void *pp_cb,
+				      void **pp_task_cb)
+{
+	struct submodule_update_clone *pp = pp_cb;
+
+	for (; pp->count < pp->list.nr; pp->count++) {
+		const struct submodule *sub = NULL;
+		const char *displaypath = NULL;
+		const struct cache_entry *ce = pp->list.entries[pp->count];
+		struct strbuf sb = STRBUF_INIT;
+		const char *update_module = NULL;
+		char *url = NULL;
+		int needs_cloning = 0;
+
+		if (ce_stage(ce)) {
+			if (pp->recursive_prefix)
+				strbuf_addf(err, "Skipping unmerged submodule %s/%s\n",
+					pp->recursive_prefix, ce->name);
+			else
+				strbuf_addf(err, "Skipping unmerged submodule %s\n",
+					ce->name);
+			continue;
+		}
+
+		sub = submodule_from_path(null_sha1, ce->name);
+		if (!sub) {
+			strbuf_addf(err, "BUG: internal error managing submodules. "
+				    "The cache could not locate '%s'", ce->name);
+			pp->print_unmatched = 1;
+			continue;
+		}
+
+		if (pp->recursive_prefix)
+			displaypath = relative_path(pp->recursive_prefix, ce->name, &sb);
+		else
+			displaypath = ce->name;
+
+		if (pp->update)
+			update_module = pp->update;
+		if (!update_module)
+			update_module = sub->update;
+		if (!update_module)
+			update_module = "checkout";
+		if (!strcmp(update_module, "none")) {
+			strbuf_addf(err, "Skipping submodule '%s'\n", displaypath);
+			continue;
+		}
+
+		/*
+		 * Looking up the url in .git/config.
+		 * We must not fall back to .gitmodules as we only want to process
+		 * configured submodules.
+		 */
+		strbuf_reset(&sb);
+		strbuf_addf(&sb, "submodule.%s.url", sub->name);
+		git_config_get_string(sb.buf, &url);
+		if (!url) {
+			/*
+			 * Only mention uninitialized submodules when its
+			 * path have been specified
+			 */
+			if (pp->pathspec.nr)
+				strbuf_addf(err, _("Submodule path '%s' not initialized\n"
+					"Maybe you want to use 'update --init'?"), displaypath);
+			continue;
+		}
+
+		strbuf_reset(&sb);
+		strbuf_addf(&sb, "%s/.git", ce->name);
+		needs_cloning = !file_exists(sb.buf);
+
+		strbuf_reset(&sb);
+		strbuf_addf(&sb, "%06o %s %d %d\t%s\n", ce->ce_mode,
+				sha1_to_hex(ce->sha1), ce_stage(ce),
+				needs_cloning, ce->name);
+		string_list_append(&pp->projectlines, sb.buf);
+
+		if (needs_cloning) {
+			fill_clone_command(cp, pp->quiet, pp->prefix, ce->name,
+					   sub->name, url, pp->reference, pp->depth);
+			pp->count++;
+			free(url);
+			return 1;
+		} else
+			free(url);
+	}
+	return 0;
+}
+
+static int update_clone_start_failure(struct child_process *cp,
+				      struct strbuf *err,
+				      void *pp_cb,
+				      void *pp_task_cb)
+{
+	struct submodule_update_clone *pp = pp_cb;
+
+	strbuf_addf(err, "error when starting a child process");
+	pp->print_unmatched = 1;
+
+	return 1;
+}
+
+static int update_clone_task_finished(int result,
+				      struct child_process *cp,
+				      struct strbuf *err,
+				      void *pp_cb,
+				      void *pp_task_cb)
+{
+	struct submodule_update_clone *pp = pp_cb;
+
+	if (!result) {
+		return 0;
+	} else {
+		strbuf_addf(err, "error in one child process");
+		pp->print_unmatched = 1;
+		return 1;
+	}
+}
+
+static int update_clone(int argc, const char **argv, const char *prefix)
+{
+	struct string_list_item *item;
+	struct submodule_update_clone pp = SUBMODULE_UPDATE_CLONE_INIT;
+
+	struct option module_list_options[] = {
+		OPT_STRING(0, "prefix", &prefix,
+			   N_("path"),
+			   N_("path into the working tree")),
+		OPT_STRING(0, "recursive_prefix", &pp.recursive_prefix,
+			   N_("path"),
+			   N_("path into the working tree, across nested "
+			      "submodule boundaries")),
+		OPT_STRING(0, "update", &pp.update,
+			   N_("string"),
+			   N_("update command for submodules")),
+		OPT_STRING(0, "reference", &pp.reference, "<repository>",
+			   N_("Use the local reference repository "
+			      "instead of a full clone")),
+		OPT_STRING(0, "depth", &pp.depth, "<depth>",
+			   N_("Create a shallow clone truncated to the "
+			      "specified number of revisions")),
+		OPT__QUIET(&pp.quiet, N_("do't print cloning progress")),
+		OPT_END()
+	};
+
+	const char *const git_submodule_helper_usage[] = {
+		N_("git submodule--helper list [--prefix=<path>] [<path>...]"),
+		NULL
+	};
+	pp.prefix = prefix;
+
+	argc = parse_options(argc, argv, prefix, module_list_options,
+			     git_submodule_helper_usage, 0);
+
+	if (module_list_compute(argc, argv, prefix, &pp.pathspec, &pp.list) < 0) {
+		printf("#unmatched\n");
+		return 1;
+	}
+
+	gitmodules_config();
+	/* Overlay the parsed .gitmodules file with .git/config */
+	git_config(git_submodule_config, NULL);
+	run_processes_parallel(1, update_clone_get_next_task,
+				  update_clone_start_failure,
+				  update_clone_task_finished,
+				  &pp);
+
+	if (pp.print_unmatched) {
+		printf("#unmatched\n");
+		return 1;
+	}
+
+	for_each_string_list_item(item, &pp.projectlines)
+		utf8_fprintf(stdout, "%s", item->string);
+
+	return 0;
+}
+
 struct cmd_struct {
 	const char *cmd;
 	int (*fn)(int, const char **, const char *);
@@ -264,6 +492,7 @@ static struct cmd_struct commands[] = {
 	{"list", module_list},
 	{"name", module_name},
 	{"clone", module_clone},
+	{"update-clone", update_clone}
 };
 
 int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
diff --git a/git-submodule.sh b/git-submodule.sh
index 9bc5c5f..9f554fb 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -664,17 +664,18 @@ cmd_update()
 		cmd_init "--" "$@" || return
 	fi
 
-	cloned_modules=
-	git submodule--helper list --prefix "$wt_prefix" "$@" | {
+	git submodule--helper update-clone ${GIT_QUIET:+--quiet} \
+		${wt_prefix:+--prefix "$wt_prefix"} \
+		${prefix:+--recursive_prefix "$prefix"} \
+		${update:+--update "$update"} \
+		${reference:+--reference "$reference"} \
+		${depth:+--depth "$depth"} \
+		"$@" | {
 	err=
-	while read mode sha1 stage sm_path
+	while read mode sha1 stage just_cloned sm_path
 	do
 		die_if_unmatched "$mode"
-		if test "$stage" = U
-		then
-			echo >&2 "Skipping unmerged submodule $prefix$sm_path"
-			continue
-		fi
+
 		name=$(git submodule--helper name "$sm_path") || exit
 		url=$(git config submodule."$name".url)
 		branch=$(get_submodule_config "$name" branch master)
@@ -691,27 +692,10 @@ cmd_update()
 
 		displaypath=$(relative_path "$prefix$sm_path")
 
-		if test "$update_module" = "none"
-		then
-			echo "Skipping submodule '$displaypath'"
-			continue
-		fi
-
-		if test -z "$url"
-		then
-			# Only mention uninitialized submodules when its
-			# path have been specified
-			test "$#" != "0" &&
-			say "$(eval_gettext "Submodule path '\$displaypath' not initialized
-Maybe you want to use 'update --init'?")"
-			continue
-		fi
-
-		if ! test -d "$sm_path"/.git && ! test -f "$sm_path"/.git
+		if test $just_cloned -eq 1
 		then
-			git submodule--helper clone ${GIT_QUIET:+--quiet} --prefix "$prefix" --path "$sm_path" --name "$name" --url "$url" "$reference" "$depth" || exit
-			cloned_modules="$cloned_modules;$name"
 			subsha1=
+			update_module=checkout
 		else
 			subsha1=$(clear_local_git_env; cd "$sm_path" &&
 				git rev-parse --verify HEAD) ||
@@ -751,13 +735,6 @@ Maybe you want to use 'update --init'?")"
 				die "$(eval_gettext "Unable to fetch in submodule path '\$displaypath'")"
 			fi
 
-			# Is this something we just cloned?
-			case ";$cloned_modules;" in
-			*";$name;"*)
-				# then there is no local change to integrate
-				update_module=checkout ;;
-			esac
-
 			must_die_on_failure=
 			case "$update_module" in
 			checkout)
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index 540771c..5991e3c 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -462,7 +462,7 @@ test_expect_success 'update --init' '
 	git config --remove-section submodule.example &&
 	test_must_fail git config submodule.example.url &&
 
-	git submodule update init > update.out &&
+	git submodule update init 2> update.out &&
 	cat update.out &&
 	test_i18ngrep "not initialized" update.out &&
 	test_must_fail git rev-parse --resolve-git-dir init/.git &&
@@ -480,7 +480,7 @@ test_expect_success 'update --init from subdirectory' '
 	mkdir -p sub &&
 	(
 		cd sub &&
-		git submodule update ../init >update.out &&
+		git submodule update ../init 2>update.out &&
 		cat update.out &&
 		test_i18ngrep "not initialized" update.out &&
 		test_must_fail git rev-parse --resolve-git-dir ../init/.git &&
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 7/8] submodule update: expose parallelism to the user

[Stefan Beller]

Expose possible parallelism either via the "--jobs" CLI parameter or
the "submodule.fetchJobs" setting.

By having the variable initialized to -1, we make sure 0 can be passed
into the parallel processing machine, which will then pick as many parallel
workers as there are CPUs.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 Documentation/git-submodule.txt |  7 ++++++-
 builtin/submodule--helper.c     | 18 ++++++++++++++----
 git-submodule.sh                |  9 +++++++++
 t/t7406-submodule-update.sh     | 12 ++++++++++++
 4 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index 1572f05..13adebf 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -16,7 +16,7 @@ SYNOPSIS
 'git submodule' [--quiet] deinit [-f|--force] [--] <path>...
 'git submodule' [--quiet] update [--init] [--remote] [-N|--no-fetch]
 	      [-f|--force] [--rebase|--merge] [--reference <repository>]
-	      [--depth <depth>] [--recursive] [--] [<path>...]
+	      [--depth <depth>] [--recursive] [--jobs <n>] [--] [<path>...]
 'git submodule' [--quiet] summary [--cached|--files] [(-n|--summary-limit) <n>]
 	      [commit] [--] [<path>...]
 'git submodule' [--quiet] foreach [--recursive] <command>
@@ -377,6 +377,11 @@ for linkgit:git-clone[1]'s `--reference` and `--shared` options carefully.
 	clone with a history truncated to the specified number of revisions.
 	See linkgit:git-clone[1]
 
+-j <n>::
+--jobs <n>::
+	This option is only valid for the update command.
+	Clone new submodules in parallel with as many jobs.
+	Defaults to the `submodule.fetchJobs` option.
 
 <path>...::
 	Paths to submodule(s). When specified this will restrict the command
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 9441f20..8002187 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -426,6 +426,7 @@ static int update_clone_task_finished(int result,
 
 static int update_clone(int argc, const char **argv, const char *prefix)
 {
+	int max_jobs = -1;
 	struct string_list_item *item;
 	struct submodule_update_clone pp = SUBMODULE_UPDATE_CLONE_INIT;
 
@@ -446,6 +447,8 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 		OPT_STRING(0, "depth", &pp.depth, "<depth>",
 			   N_("Create a shallow clone truncated to the "
 			      "specified number of revisions")),
+		OPT_INTEGER('j', "jobs", &max_jobs,
+			    N_("parallel jobs")),
 		OPT__QUIET(&pp.quiet, N_("do't print cloning progress")),
 		OPT_END()
 	};
@@ -467,10 +470,17 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 	gitmodules_config();
 	/* Overlay the parsed .gitmodules file with .git/config */
 	git_config(git_submodule_config, NULL);
-	run_processes_parallel(1, update_clone_get_next_task,
-				  update_clone_start_failure,
-				  update_clone_task_finished,
-				  &pp);
+
+	if (max_jobs < 0)
+		max_jobs = config_parallel_submodules();
+	if (max_jobs < 0)
+		max_jobs = 1;
+
+	run_processes_parallel(max_jobs,
+			       update_clone_get_next_task,
+			       update_clone_start_failure,
+			       update_clone_task_finished,
+			       &pp);
 
 	if (pp.print_unmatched) {
 		printf("#unmatched\n");
diff --git a/git-submodule.sh b/git-submodule.sh
index 9f554fb..10c5af9 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -645,6 +645,14 @@ cmd_update()
 		--depth=*)
 			depth=$1
 			;;
+		-j|--jobs)
+			case "$2" in '') usage ;; esac
+			jobs="--jobs=$2"
+			shift
+			;;
+		--jobs=*)
+			jobs=$1
+			;;
 		--)
 			shift
 			break
@@ -670,6 +678,7 @@ cmd_update()
 		${update:+--update "$update"} \
 		${reference:+--reference "$reference"} \
 		${depth:+--depth "$depth"} \
+		${jobs:+$jobs} \
 		"$@" | {
 	err=
 	while read mode sha1 stage just_cloned sm_path
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index dda3929..7fd5142 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -774,4 +774,16 @@ test_expect_success 'submodule update --recursive drops module name before recur
 	 test_i18ngrep "Submodule path .deeper/submodule/subsubmodule.: checked out" actual
 	)
 '
+
+test_expect_success 'submodule update can be run in parallel' '
+	(cd super2 &&
+	 GIT_TRACE=$(pwd)/trace.out git submodule update --jobs 7 &&
+	 grep "7 tasks" trace.out &&
+	 git config submodule.fetchJobs 8 &&
+	 GIT_TRACE=$(pwd)/trace.out git submodule update &&
+	 grep "8 tasks" trace.out &&
+	 GIT_TRACE=$(pwd)/trace.out git submodule update --jobs 9 &&
+	 grep "9 tasks" trace.out
+	)
+'
 test_done
-- 
2.7.0.rc1.7.gf4541cb.dirty

[PATCHv7 8/8] clone: allow an explicit argument for parallel submodule clones

[Stefan Beller]

Just pass it along to "git submodule update", which may pick reasonable
defaults if you don't specify an explicit number.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 Documentation/git-clone.txt |  6 +++++-
 builtin/clone.c             | 19 +++++++++++++------
 t/t7406-submodule-update.sh | 15 +++++++++++++++
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 6bf000d..6db7b6d 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -14,7 +14,7 @@ SYNOPSIS
 	  [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
 	  [--dissociate] [--separate-git-dir <git dir>]
 	  [--depth <depth>] [--[no-]single-branch]
-	  [--recursive | --recurse-submodules] [--] <repository>
+	  [--recursive | --recurse-submodules] [--jobs <n>] [--] <repository>
 	  [<directory>]
 
 DESCRIPTION
@@ -221,6 +221,10 @@ objects from the source repository into a pack in the cloned repository.
 	The result is Git repository can be separated from working
 	tree.
 
+-j <n>::
+--jobs <n>::
+	The number of submodules fetched at the same time.
+	Defaults to the `submodule.fetchJobs` option.
 
 <repository>::
 	The (possibly remote) repository to clone from.  See the
diff --git a/builtin/clone.c b/builtin/clone.c
index a0b3cd9..b004fb4 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -50,6 +50,7 @@ static int option_progress = -1;
 static struct string_list option_config;
 static struct string_list option_reference;
 static int option_dissociate;
+static int max_jobs = -1;
 
 static struct option builtin_clone_options[] = {
 	OPT__VERBOSITY(&option_verbosity),
@@ -72,6 +73,8 @@ static struct option builtin_clone_options[] = {
 		    N_("initialize submodules in the clone")),
 	OPT_BOOL(0, "recurse-submodules", &option_recursive,
 		    N_("initialize submodules in the clone")),
+	OPT_INTEGER('j', "jobs", &max_jobs,
+		    N_("number of submodules cloned in parallel")),
 	OPT_STRING(0, "template", &option_template, N_("template-directory"),
 		   N_("directory from which templates will be used")),
 	OPT_STRING_LIST(0, "reference", &option_reference, N_("repo"),
@@ -95,10 +98,6 @@ static struct option builtin_clone_options[] = {
 	OPT_END()
 };
 
-static const char *argv_submodule[] = {
-	"submodule", "update", "--init", "--recursive", NULL
-};
-
 static const char *get_repo_path_1(struct strbuf *path, int *is_bundle)
 {
 	static char *suffix[] = { "/.git", "", ".git/.git", ".git" };
@@ -724,8 +723,16 @@ static int checkout(void)
 	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
 			   sha1_to_hex(sha1), "1", NULL);
 
-	if (!err && option_recursive)
-		err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
+	if (!err && option_recursive) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+		argv_array_pushl(&args, "submodule", "update", "--init", "--recursive", NULL);
+
+		if (max_jobs != -1)
+			argv_array_pushf(&args, "--jobs=%d", max_jobs);
+
+		err = run_command_v_opt(args.argv, RUN_GIT_CMD);
+		argv_array_clear(&args);
+	}
 
 	return err;
 }
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index 7fd5142..090891e 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -786,4 +786,19 @@ test_expect_success 'submodule update can be run in parallel' '
 	 grep "9 tasks" trace.out
 	)
 '
+
+test_expect_success 'git clone passes the parallel jobs config on to submodules' '
+	test_when_finished "rm -rf super4" &&
+	GIT_TRACE=$(pwd)/trace.out git clone --recurse-submodules --jobs 7 . super4 &&
+	grep "7 tasks" trace.out &&
+	rm -rf super4 &&
+	git config --global submodule.fetchJobs 8 &&
+	GIT_TRACE=$(pwd)/trace.out git clone --recurse-submodules . super4 &&
+	grep "8 tasks" trace.out &&
+	rm -rf super4 &&
+	GIT_TRACE=$(pwd)/trace.out git clone --recurse-submodules --jobs 9 . super4 &&
+	grep "9 tasks" trace.out &&
+	rm -rf super4
+'
+
 test_done
-- 
2.7.0.rc1.7.gf4541cb.dirty

Re: [PATCHv7 0/8] Expose submodule parallelism to the user

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> This is a resend of sb/submodule-parallel-update and is available
> at github[1] as well.  It applies on top of
> sb/submodule-parallel-fetch
>
> What does it do?
> ---
> This series should finish the on going efforts of parallelizing
> submodule network traffic. The patches contain tests for
>   clone
>   fetch
>   submodule update
> to use the actual parallelism both via command line as well as a
> configured option. I decided to go with "submodule.fetchJobs" for
> all three for now.
>
> What changed to v5,6?
> ---
> No major changes, I just made it compile again as the order of parameters
> to the parallel processing engine changed.

OK, I am in the process of replacing it but I am also rewinding
'next' and updating 'maint' today, so this update may not be
published until tomorrow's integration cycle.

Here are the changes I noticed, just to double check:

 - There is no change in [1-3/8] relative to the previous round;
   I'll keep the one that has been in my tree to preserve their
   committer/author dates.

 - In the log message of [4/8], the misspelt "submodule.jobs" in the
   previous round now reads "submodule.fetchJobs".

 - There is no change in [5-8/8] relative to the previous round.

Thanks.

Re: [PATCHv7 0/8] Expose submodule parallelism to the user

[Stefan Beller]

On Tue, Jan 12, 2016 at 3:50 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Stefan Beller <sbeller@google.com> writes:
>
>> This is a resend of sb/submodule-parallel-update and is available
>> at github[1] as well.  It applies on top of
>> sb/submodule-parallel-fetch
>>
>> What does it do?
>> ---
>> This series should finish the on going efforts of parallelizing
>> submodule network traffic. The patches contain tests for
>>   clone
>>   fetch
>>   submodule update
>> to use the actual parallelism both via command line as well as a
>> configured option. I decided to go with "submodule.fetchJobs" for
>> all three for now.
>>
>> What changed to v5,6?
>> ---
>> No major changes, I just made it compile again as the order of parameters
>> to the parallel processing engine changed.
>
> OK, I am in the process of replacing it but I am also rewinding
> 'next' and updating 'maint' today, so this update may not be
> published until tomorrow's integration cycle.
>
> Here are the changes I noticed, just to double check:
>
>  - There is no change in [1-3/8] relative to the previous round;
>    I'll keep the one that has been in my tree to preserve their
>    committer/author dates.
>
>  - In the log message of [4/8], the misspelt "submodule.jobs" in the
>    previous round now reads "submodule.fetchJobs".
>
>  - There is no change in [5-8/8] relative to the previous round.

Yeah that's it.

Additionally to that I needed to switch the order of arguments for the
parallel processing calls, too, to make it compile again.
I assume I just did that work twice as the previous version
ought to compile, too.

But apart from these 2 things I did no other changes.

>
> Thanks.

Re: [PATCHv7 0/8] Expose submodule parallelism to the user

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> Additionally to that I needed to switch the order of arguments for the
> parallel processing calls, too, to make it compile again.

That sounds as if the previous one that was queued did not compile,
but I didn't recall seeing such breakage.  Also comparison between
corresponding patches did not show such a change, either.

But perhaps ...

> I assume I just did that work twice as the previous version
> ought to compile, too.

... means that you didn't need such a switch after all, and the
re-sent series didn't have it.

I am just making sure that I got the right version in my tree, so
please don't behave as if I am accusing you that you advertised that
you did more work than you actually did and go defensive ;-) If the
reason I didn't see one kind of change in the series I received is
because it didn't have to be done and the description mistakenly
said that such a change is included, that is perfectly fine.

Thanks.

Re: [PATCHv7 0/8] Expose submodule parallelism to the user

[Stefan Beller]

On Wed, Jan 13, 2016 at 8:56 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Stefan Beller <sbeller@google.com> writes:
>
>> Additionally to that I needed to switch the order of arguments for the
>> parallel processing calls, too, to make it compile again.
>
> That sounds as if the previous one that was queued did not compile,
> but I didn't recall seeing such breakage.  Also comparison between
> corresponding patches did not show such a change, either.
>
> But perhaps ...
>
>> I assume I just did that work twice as the previous version
>> ought to compile, too.
>
> ... means that you didn't need such a switch after all, and the
> re-sent series didn't have it.

My local state has had the switch, and I needed to make it before sending out
the latest version. I do not recall doing that to the previous version, but that
version is fine, too.

Which means I may have missed some review comment (if any) or
that I am forgetting things (I was on holidays for 3 weeks, barely touching
an electronic device).

>
> I am just making sure that I got the right version in my tree, so
> please don't behave as if I am accusing you that you advertised that
> you did more work than you actually did and go defensive ;-)

It should not sound as if I go defensive by being accused. I just want
to point out I may have missed a thing on my end, so double caution
for reviewers may be warranted. It was badly worded though.

>  If the
> reason I didn't see one kind of change in the series I received is
> because it didn't have to be done and the description mistakenly
> said that such a change is included, that is perfectly fine.
>
> Thanks.

Thanks,
Stefan

Re: [PATCHv7 0/8] Expose submodule parallelism to the user

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> This is a resend of sb/submodule-parallel-update and is available
> at github[1] as well.  It applies on top of
> sb/submodule-parallel-fetch
>
> What does it do?
> ---
> This series should finish the on going efforts of parallelizing
> submodule network traffic. The patches contain tests for
>   clone
>   fetch
>   submodule update
> to use the actual parallelism both via command line as well as a
> configured option. I decided to go with "submodule.fetchJobs" for
> all three for now.
>
> What changed to v5,6?
> ---
> No major changes, I just made it compile again as the order of parameters
> to the parallel processing engine changed.

This hasn't seen any reviews since it was posted.  Is anybody
interested in seeing this topic moving forward?