Merge lp:~laurynas-biveinis/percona-server/bug1239062 into lp:percona-server/5.6

[Laurynas Biveinis]

2nd MP:
- added a note to @return tag in the header comment;
- rebased on the current trunk.

http://jenkins.percona.com/job/percona-server-5.6-param/403/

1st MP:

Fix bug 1239062 (InnoDB: Error: semaphore wait has lasted > 600
seconds. InnoDB: We intentionally crash the server, because it appears
to be hung. InnoDB: Assertion failure in thread <nr> in file
srv0srv.cc line 2124. Abort (sig=6) in srv_error_monitor_thread
(III)).

The issue is the backoff loop in log_preflush_pool_modified_pages()
turning into an infinite loop when the function is called with dirty
buffer pool, the innermost loop enters, and a buffer pool flush list
flush that fully cleans the pool starts and fully completes before the
next buf_flush_list_in_progress() check. Then that check will keep on
returning false until something dirties the buffer pool, which may
never happen.

Fix by adjusting buf_flush_flush_list_in_progress() to return true
also in the case when all the buffer pool instances are clean.

http://jenkins.percona.com/job/percona-server-5.6-param/389/

[Vlad Lesin (vlad-lesin)]

I think the fact that buf_flush_flush_list_in_progress() returns true not only if flush is in progress but also if flush list is clean should be documented in "@return" section.

review: Needs Fixing (g2)

[Vlad Lesin (vlad-lesin)]

review: Approve (g2)

[Stewart Smith (stewart)]

review: Approve

=== modified file 'Percona-Server/storage/innobase/include/buf0flu.h'
--- Percona-Server/storage/innobase/include/buf0flu.h	2013-10-23 08:48:28 +0000
+++ Percona-Server/storage/innobase/include/buf0flu.h	2013-11-05 07:33:32 +0000
@@ -279,9 +279,9 @@
 #endif /* !UNIV_HOTBACKUP */
 
 /******************************************************************//**
-Check if a flush list flush is in progress for any buffer pool instance for
-heuristic purposes.
-@return true if flush list flush is in progress  */
+Check if a flush list flush is in progress for any buffer pool instance, or if
+all the instances are clean, for heuristic purposes.
+@return true if flush list flush is in progress or buffer pool is clean */
 UNIV_INLINE
 bool
 buf_flush_flush_list_in_progress(void)

=== modified file 'Percona-Server/storage/innobase/include/buf0flu.ic'
--- Percona-Server/storage/innobase/include/buf0flu.ic	2013-10-23 08:48:28 +0000
+++ Percona-Server/storage/innobase/include/buf0flu.ic	2013-11-05 07:33:32 +0000
@@ -137,14 +137,16 @@
 #endif /* !UNIV_HOTBACKUP */
 
 /******************************************************************//**
-Check if a flush list flush is in progress for any buffer pool instance for
-heuristic purposes.
-@return true if flush list flush is in progress  */
+Check if a flush list flush is in progress for any buffer pool instance, or if
+all the instances are clean, for heuristic purposes.
+@return true if flush list flush is in progress or buffer pool is clean */
 UNIV_INLINE
 bool
 buf_flush_flush_list_in_progress(void)
 /*==================================*/
 {
+	bool	all_clean = true;
+
 	for (ulint i = 0; i < srv_buf_pool_instances; i++) {
 
 		const buf_pool_t* buf_pool = buf_pool_from_array(i);
@@ -153,6 +155,13 @@
 
 			return(true);
 		}
+
+		if (all_clean) {
+
+			all_clean = (UT_LIST_GET_LEN(buf_pool->flush_list)
+				     == 0);
+		}
+
 	}
-	return(false);
+	return(all_clean);
 }