140 lines
4.9 KiB
Diff
140 lines
4.9 KiB
Diff
mysql is not accounting for the "guard page" when setting thread stack size
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requests. This is fatal on PPC systems, which may use guard pages as large
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as 64K. This patch also documents the IA64 situation a bit better.
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Note: there are quite a few other setstacksize calls besides the two in
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mysqld.cc; is it important to fix any of the others?
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Filed upstream at http://bugs.mysql.com/bug.php?id=35019
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diff -up mysql-5.5.28/sql/mysqld.cc.p5 mysql-5.5.28/sql/mysqld.cc
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--- mysql-5.5.28/sql/mysqld.cc.p5 2012-08-29 10:50:46.000000000 +0200
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+++ mysql-5.5.28/sql/mysqld.cc 2012-12-06 14:13:59.765407494 +0100
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@@ -2599,6 +2599,70 @@ static void init_signals(void)
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}
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+/* pthread_attr_setstacksize without so much platform-dependency */
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+/* returns the actual stack size if possible */
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+static size_t my_setstacksize(pthread_attr_t *attr, size_t stacksize)
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+{
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+ size_t guard_size = 0;
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+
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+#if defined(__ia64__) || defined(__ia64)
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+ /*
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+ On IA64, half of the requested stack size is used for "normal stack"
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+ and half for "register stack". The space measured by check_stack_overrun
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+ is the "normal stack", so double the request to make sure we have the
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+ caller-expected amount of normal stack.
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+
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+ NOTE: there is no guarantee that the register stack can't grow faster
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+ than normal stack, so it's very unclear that we won't dump core due to
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+ stack overrun despite check_stack_overrun's efforts. Experimentation
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+ shows that in the execution_constants test, the register stack grows
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+ less than half as fast as normal stack, but perhaps other scenarios are
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+ less forgiving. If it turns out that more space is needed for the
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+ register stack, that could be forced (rather inefficiently) by using a
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+ multiplier higher than 2 here.
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+ */
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+ stacksize *= 2;
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+#endif
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+
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+ /*
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+ On many machines, the "guard space" is subtracted from the requested
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+ stack size, and that space is quite large on some platforms. So add
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+ it to our request, if we can find out what it is.
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+
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+ FIXME: autoconfiscate use of pthread_attr_getguardsize
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+ */
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+ if (pthread_attr_getguardsize(attr, &guard_size))
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+ guard_size = 0; /* if can't find it out, treat as 0 */
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+
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+ pthread_attr_setstacksize(attr, stacksize + guard_size);
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+
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+ /* Retrieve actual stack size if possible */
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+#ifdef HAVE_PTHREAD_ATTR_GETSTACKSIZE
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+ {
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+ size_t real_stack_size= 0;
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+ /* We must ignore real_stack_size = 0 as Solaris 2.9 can return 0 here */
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+ if (pthread_attr_getstacksize(attr, &real_stack_size) == 0 &&
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+ real_stack_size > guard_size)
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+ {
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+ real_stack_size -= guard_size;
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+ if (real_stack_size < stacksize)
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+ {
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+ if (global_system_variables.log_warnings)
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+ sql_print_warning("Asked for %ld thread stack, but got %ld",
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+ (long) stacksize, (long) real_stack_size);
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+ stacksize= real_stack_size;
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+ }
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+ }
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+ }
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+#endif
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+
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+#if defined(__ia64__) || defined(__ia64)
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+ stacksize /= 2;
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+#endif
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+ return stacksize;
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+}
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+
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+
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static void start_signal_handler(void)
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{
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int error;
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@@ -2609,15 +2673,7 @@ static void start_signal_handler(void)
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#if !defined(HAVE_DEC_3_2_THREADS)
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pthread_attr_setscope(&thr_attr,PTHREAD_SCOPE_SYSTEM);
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(void) pthread_attr_setdetachstate(&thr_attr,PTHREAD_CREATE_DETACHED);
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-#if defined(__ia64__) || defined(__ia64)
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- /*
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- Peculiar things with ia64 platforms - it seems we only have half the
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- stack size in reality, so we have to double it here
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- */
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- pthread_attr_setstacksize(&thr_attr,my_thread_stack_size*2);
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-#else
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- pthread_attr_setstacksize(&thr_attr,my_thread_stack_size);
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-#endif
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+ (void) my_setstacksize(&thr_attr,my_thread_stack_size);
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#endif
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mysql_mutex_lock(&LOCK_thread_count);
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@@ -4398,36 +4454,8 @@ int mysqld_main(int argc, char **argv)
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unireg_abort(1); // Will do exit
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init_signals();
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-#if defined(__ia64__) || defined(__ia64)
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- /*
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- Peculiar things with ia64 platforms - it seems we only have half the
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- stack size in reality, so we have to double it here
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- */
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- pthread_attr_setstacksize(&connection_attrib,my_thread_stack_size*2);
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-#else
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- pthread_attr_setstacksize(&connection_attrib,my_thread_stack_size);
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-#endif
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#ifdef HAVE_PTHREAD_ATTR_GETSTACKSIZE
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- {
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- /* Retrieve used stack size; Needed for checking stack overflows */
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- size_t stack_size= 0;
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- pthread_attr_getstacksize(&connection_attrib, &stack_size);
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-#if defined(__ia64__) || defined(__ia64)
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- stack_size/= 2;
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-#endif
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- /* We must check if stack_size = 0 as Solaris 2.9 can return 0 here */
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- if (stack_size && stack_size < my_thread_stack_size)
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- {
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- if (global_system_variables.log_warnings)
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- sql_print_warning("Asked for %lu thread stack, but got %ld",
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- my_thread_stack_size, (long) stack_size);
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-#if defined(__ia64__) || defined(__ia64)
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- my_thread_stack_size= stack_size*2;
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-#else
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- my_thread_stack_size= stack_size;
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-#endif
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- }
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- }
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+ my_thread_stack_size = my_setstacksize(&connection_attrib,my_thread_stack_size);
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#endif
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(void) thr_setconcurrency(concurrency); // 10 by default
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