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From: Matheus Tavares <matheus.bernardino@usp.br>
To: git@vger.kernel.org
Cc: Christian Couder <christian.couder@gmail.com>,
	Olga Telezhnaya <olyatelezhnaya@gmail.com>,
	Nguyễn Thái Ngọc Duy  <pclouds@gmail.com>,
	Brandon Williams <bwilliams.eng@gmail.com>,
	Ævar Arnfjörð Bjarmason  <avarab@gmail.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: [GSoC][PATCH 3/4] grep: disable grep_read_mutex when possible
Date: Sat, 10 Aug 2019 17:27:29 -0300
Message-ID: <d2e3f4eac24d26210f8962ebd82fd24a99c91fdf.1565468806.git.matheus.bernardino@usp.br> (raw)
In-Reply-To: <cover.1565468806.git.matheus.bernardino@usp.br>

git-grep uses 'grep_read_mutex' to protect some object reading
operations. But these have their own internal lock now, which ensure a
better performance (with more parallel regions). So, disable the former
when it's possible to use the latter, with enable_obj_read_lock().

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---
 builtin/grep.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/builtin/grep.c b/builtin/grep.c
index a871bad8ad..fa51392222 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -205,7 +205,17 @@ static void start_threads(struct grep_opt *opt)
 	pthread_cond_init(&cond_add, NULL);
 	pthread_cond_init(&cond_write, NULL);
 	pthread_cond_init(&cond_result, NULL);
-	grep_use_locks = GREP_USE_ALL_LOCKS;
+	if (recurse_submodules || opt->allow_textconv) {
+		/*
+		 * textconv and submodules' operations are not thread-safe yet
+		 * so we must use grep_read_lock when grepping multithreaded
+		 * with these options.
+		 */
+		grep_use_locks = GREP_USE_ALL_LOCKS;
+	} else {
+		grep_use_locks = GREP_USE_ATTR_LOCK;
+		enable_obj_read_lock();
+	}
 
 	for (i = 0; i < ARRAY_SIZE(todo); i++) {
 		strbuf_init(&todo[i].out, 0);
@@ -227,7 +237,7 @@ static void start_threads(struct grep_opt *opt)
 	}
 }
 
-static int wait_all(void)
+static int wait_all(struct grep_opt *opt)
 {
 	int hit = 0;
 	int i;
@@ -263,6 +273,9 @@ static int wait_all(void)
 	pthread_cond_destroy(&cond_write);
 	pthread_cond_destroy(&cond_result);
 	grep_use_locks = 0;
+	if (!recurse_submodules && !opt->allow_textconv) {
+		disable_obj_read_lock();
+	}
 
 	return hit;
 }
@@ -1140,7 +1153,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	}
 
 	if (num_threads > 1)
-		hit |= wait_all();
+		hit |= wait_all(&opt);
 	if (hit && show_in_pager)
 		run_pager(&opt, prefix);
 	clear_pathspec(&pathspec);
-- 
2.22.0


  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-10 20:27 [GSoC][PATCH 0/4] grep: re-enable threads when cached, w/ parallel inflation Matheus Tavares
2019-08-10 20:27 ` [GSoC][PATCH 1/4] object-store: add lock to read_object_file_extended() Matheus Tavares
2019-08-10 20:27 ` [GSoC][PATCH 2/4] grep: allow locks to be enabled individually Matheus Tavares
2019-08-10 20:27 ` Matheus Tavares [this message]
2019-08-10 20:27 ` [GSoC][PATCH 4/4] grep: re-enable threads in some non-worktree cases Matheus Tavares
2019-09-30  1:50 ` [PATCH v2 00/11] grep: improve threading and fix race conditions Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 01/11] grep: fix race conditions on userdiff calls Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 02/11] grep: fix race conditions at grep_submodule() Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 03/11] grep: fix racy calls in grep_objects() Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 04/11] replace-object: make replace operations thread-safe Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 05/11] object-store: allow threaded access to object reading Matheus Tavares
2019-11-12  2:54     ` Jonathan Tan
2019-11-13  5:20       ` Jeff King
2019-11-14  5:57         ` Matheus Tavares Bernardino
2019-11-14  6:01           ` Jeff King
2019-11-14 18:15             ` Jonathan Tan
2019-11-15  4:12               ` Jeff King
2019-09-30  1:50   ` [PATCH v2 06/11] grep: replace grep_read_mutex by internal obj read lock Matheus Tavares
2019-10-01 19:23     ` [PATCH] squash! " Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 07/11] submodule-config: add skip_if_read option to repo_read_gitmodules() Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 08/11] grep: allow submodule functions to run in parallel Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 09/11] grep: protect packed_git [re-]initialization Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 10/11] grep: re-enable threads in non-worktree case Matheus Tavares
2019-09-30  1:50   ` [PATCH v2 11/11] grep: move driver pre-load out of critical section Matheus Tavares

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