234 lines
6.8 KiB
Diff
234 lines
6.8 KiB
Diff
From 4f6cb65ce4d643aca0c6bf7db2e8b32c0d08eb89 Mon Sep 17 00:00:00 2001
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From: Bruno Haible <bruno@clisp.org>
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Date: Sat, 24 Dec 2016 18:21:59 +0100
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Subject: [PATCH 1/2] lock test: Fix performance problem on multi-core
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machines.
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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* tests/test-lock.c (USE_VOLATILE): New macro.
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(struct atomic_int): New type.
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(init_atomic_int, get_atomic_int_value, set_atomic_int_value): New
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functions.
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(lock_checker_done, rwlock_checker_done, reclock_checker_done): Define
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as 'struct atomic_int'.
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(lock_checker_thread, test_lock, rwlock_checker_thread, test_rwlock,
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reclock_checker_thread, test_recursive_lock): Use the new functions.
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Reported by Eric Blake in
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https://www.redhat.com/archives/libvir-list/2012-March/msg00854.html
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and by Pádraig Brady in
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http://lists.gnu.org/archive/html/bug-gnulib/2016-12/msg00117.html.
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Upstream-commit: 480d374e596a0ee3fed168ab42cd84c313ad3c89
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Signed-off-by: Kamil Dudka <kdudka@redhat.com>
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---
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gnulib-tests/test-lock.c | 79 ++++++++++++++++++++++++++++++++++++++++--------
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1 file changed, 67 insertions(+), 12 deletions(-)
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diff --git a/gnulib-tests/test-lock.c b/gnulib-tests/test-lock.c
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index cb734b4..aa6de27 100644
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--- a/gnulib-tests/test-lock.c
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+++ b/gnulib-tests/test-lock.c
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@@ -50,6 +50,13 @@
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Uncomment this to see if the operating system has a fair scheduler. */
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#define EXPLICIT_YIELD 1
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+/* Whether to use 'volatile' on some variables that communicate information
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+ between threads. If set to 0, a lock is used to protect these variables.
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+ If set to 1, 'volatile' is used; this is theoretically equivalent but can
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+ lead to much slower execution (e.g. 30x slower total run time on a 40-core
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+ machine. */
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+#define USE_VOLATILE 0
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+
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/* Whether to print debugging messages. */
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#define ENABLE_DEBUGGING 0
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@@ -103,6 +110,51 @@
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# define yield()
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#endif
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+#if USE_VOLATILE
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+struct atomic_int {
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+ volatile int value;
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+};
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+static void
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+init_atomic_int (struct atomic_int *ai)
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+{
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+}
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+static int
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+get_atomic_int_value (struct atomic_int *ai)
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+{
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+ return ai->value;
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+}
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+static void
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+set_atomic_int_value (struct atomic_int *ai, int new_value)
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+{
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+ ai->value = new_value;
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+}
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+#else
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+struct atomic_int {
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+ gl_lock_define (, lock)
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+ int value;
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+};
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+static void
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+init_atomic_int (struct atomic_int *ai)
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+{
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+ gl_lock_init (ai->lock);
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+}
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+static int
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+get_atomic_int_value (struct atomic_int *ai)
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+{
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+ gl_lock_lock (ai->lock);
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+ int ret = ai->value;
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+ gl_lock_unlock (ai->lock);
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+ return ret;
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+}
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+static void
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+set_atomic_int_value (struct atomic_int *ai, int new_value)
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+{
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+ gl_lock_lock (ai->lock);
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+ ai->value = new_value;
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+ gl_lock_unlock (ai->lock);
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+}
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+#endif
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+
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#define ACCOUNT_COUNT 4
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static int account[ACCOUNT_COUNT];
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@@ -170,12 +222,12 @@ lock_mutator_thread (void *arg)
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return NULL;
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}
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-static volatile int lock_checker_done;
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+static struct atomic_int lock_checker_done;
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static void *
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lock_checker_thread (void *arg)
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{
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- while (!lock_checker_done)
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+ while (get_atomic_int_value (&lock_checker_done) == 0)
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{
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dbgprintf ("Checker %p before check lock\n", gl_thread_self_pointer ());
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gl_lock_lock (my_lock);
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@@ -200,7 +252,8 @@ test_lock (void)
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/* Initialization. */
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for (i = 0; i < ACCOUNT_COUNT; i++)
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account[i] = 1000;
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- lock_checker_done = 0;
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+ init_atomic_int (&lock_checker_done);
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+ set_atomic_int_value (&lock_checker_done, 0);
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/* Spawn the threads. */
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checkerthread = gl_thread_create (lock_checker_thread, NULL);
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@@ -210,7 +263,7 @@ test_lock (void)
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/* Wait for the threads to terminate. */
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for (i = 0; i < THREAD_COUNT; i++)
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gl_thread_join (threads[i], NULL);
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- lock_checker_done = 1;
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+ set_atomic_int_value (&lock_checker_done, 1);
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gl_thread_join (checkerthread, NULL);
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check_accounts ();
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}
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@@ -254,12 +307,12 @@ rwlock_mutator_thread (void *arg)
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return NULL;
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}
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-static volatile int rwlock_checker_done;
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+static struct atomic_int rwlock_checker_done;
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static void *
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rwlock_checker_thread (void *arg)
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{
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- while (!rwlock_checker_done)
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+ while (get_atomic_int_value (&rwlock_checker_done) == 0)
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{
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dbgprintf ("Checker %p before check rdlock\n", gl_thread_self_pointer ());
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gl_rwlock_rdlock (my_rwlock);
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@@ -284,7 +337,8 @@ test_rwlock (void)
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/* Initialization. */
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for (i = 0; i < ACCOUNT_COUNT; i++)
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account[i] = 1000;
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- rwlock_checker_done = 0;
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+ init_atomic_int (&rwlock_checker_done);
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+ set_atomic_int_value (&rwlock_checker_done, 0);
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/* Spawn the threads. */
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for (i = 0; i < THREAD_COUNT; i++)
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@@ -295,7 +349,7 @@ test_rwlock (void)
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/* Wait for the threads to terminate. */
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for (i = 0; i < THREAD_COUNT; i++)
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gl_thread_join (threads[i], NULL);
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- rwlock_checker_done = 1;
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+ set_atomic_int_value (&rwlock_checker_done, 1);
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for (i = 0; i < THREAD_COUNT; i++)
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gl_thread_join (checkerthreads[i], NULL);
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check_accounts ();
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@@ -356,12 +410,12 @@ reclock_mutator_thread (void *arg)
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return NULL;
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}
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-static volatile int reclock_checker_done;
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+static struct atomic_int reclock_checker_done;
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static void *
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reclock_checker_thread (void *arg)
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{
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- while (!reclock_checker_done)
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+ while (get_atomic_int_value (&reclock_checker_done) == 0)
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{
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dbgprintf ("Checker %p before check lock\n", gl_thread_self_pointer ());
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gl_recursive_lock_lock (my_reclock);
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@@ -386,7 +440,8 @@ test_recursive_lock (void)
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/* Initialization. */
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for (i = 0; i < ACCOUNT_COUNT; i++)
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account[i] = 1000;
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- reclock_checker_done = 0;
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+ init_atomic_int (&reclock_checker_done);
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+ set_atomic_int_value (&reclock_checker_done, 0);
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/* Spawn the threads. */
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checkerthread = gl_thread_create (reclock_checker_thread, NULL);
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@@ -396,7 +451,7 @@ test_recursive_lock (void)
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/* Wait for the threads to terminate. */
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for (i = 0; i < THREAD_COUNT; i++)
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gl_thread_join (threads[i], NULL);
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- reclock_checker_done = 1;
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+ set_atomic_int_value (&reclock_checker_done, 1);
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gl_thread_join (checkerthread, NULL);
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check_accounts ();
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}
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--
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2.7.4
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From 0d04ee8ddedb2bf33d64f148f246a3b7ec4fef21 Mon Sep 17 00:00:00 2001
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From: Kamil Dudka <kdudka@redhat.com>
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Date: Mon, 23 Jan 2017 12:35:41 +0100
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Subject: [PATCH 2/2] test-lock: disable the rwlock test
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It hangs indefinitely if the system rwlock implementation does not
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prevent writer starvation (and glibc does not implement it).
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Bug: http://www.mail-archive.com/bug-gnulib@gnu.org/msg33017.html
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---
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gnulib-tests/test-lock.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/gnulib-tests/test-lock.c b/gnulib-tests/test-lock.c
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index aa6de27..5af0a6c 100644
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--- a/gnulib-tests/test-lock.c
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+++ b/gnulib-tests/test-lock.c
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@@ -42,7 +42,7 @@
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Uncomment some of these, to verify that all tests crash if no locking
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is enabled. */
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#define DO_TEST_LOCK 1
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-#define DO_TEST_RWLOCK 1
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+#define DO_TEST_RWLOCK 0
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#define DO_TEST_RECURSIVE_LOCK 1
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#define DO_TEST_ONCE 1
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--
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2.7.4
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