Import wiredtiger-wiredtiger-mongodb-2.8-rc6-53-gd38a68b.tar.gz from wiredtiger branch mongodb-2.8

(cherry picked from commit 746d9b99a8dc0301c1593bd4dc62fc8433435c7e)

4 files changed, 32 insertions, 8 deletions

diff --git a/src/third_party/wiredtiger/src/include/cache.i b/src/third_party/wiredtiger/src/include/cache.i
index 0295451ef11..b1ace5e6a80 100644
--- a/src/third_party/wiredtiger/src/include/cache.i
+++ b/src/third_party/wiredtiger/src/include/cache.i
@@ -175,4 +175,3 @@ __wt_cache_full_check(WT_SESSION_IMPL *session)
 
 	return (__wt_cache_wait(session, full));
 }
-
diff --git a/src/third_party/wiredtiger/src/log/log.c b/src/third_party/wiredtiger/src/log/log.c
index a173a829436..5e1256aec07 100644
--- a/src/third_party/wiredtiger/src/log/log.c
+++ b/src/third_party/wiredtiger/src/log/log.c
@@ -861,12 +861,12 @@ __log_release(WT_SESSION_IMPL *session, WT_LOGSLOT *slot)
 	WT_LOG *log;
 	WT_LSN sync_lsn;
 	size_t write_size;
-	int locked;
+	int locked, yield_count;
 	WT_DECL_SPINLOCK_ID(id);			/* Must appear last */
 
 	conn = S2C(session);
 	log = conn->log;
-	locked = 0;
+	locked = yield_count = 0;
 
 	/* Write the buffered records */
 	if (F_ISSET(slot, SLOT_BUFFERED)) {
@@ -880,8 +880,13 @@ __log_release(WT_SESSION_IMPL *session, WT_LOGSLOT *slot)
 	 * Wait for earlier groups to finish, otherwise there could be holes
 	 * in the log file.
 	 */
-	while (LOG_CMP(&log->write_lsn, &slot->slot_release_lsn) != 0)
-		__wt_yield();
+	while (LOG_CMP(&log->write_lsn, &slot->slot_release_lsn) != 0) {
+		if (++yield_count < 100)
+			__wt_yield();
+		else
+			WT_ERR(__wt_cond_wait(
+			    session, log->log_write_cond, 2000));
+	}
 	log->write_lsn = slot->slot_end_lsn;
 	WT_ERR(__wt_cond_signal(session, log->log_write_cond));
 
diff --git a/src/third_party/wiredtiger/src/log/log_slot.c b/src/third_party/wiredtiger/src/log/log_slot.c
index cb959f28bd7..611587aaa8e 100644
--- a/src/third_party/wiredtiger/src/log/log_slot.c
+++ b/src/third_party/wiredtiger/src/log/log_slot.c
@@ -260,10 +260,16 @@ __wt_log_slot_notify(WT_SESSION_IMPL *session, WT_LOGSLOT *slot)
 int
 __wt_log_slot_wait(WT_SESSION_IMPL *session, WT_LOGSLOT *slot)
 {
+	int yield_count;
+
+	yield_count = 0;
 	WT_UNUSED(session);
 
 	while (slot->slot_state > WT_LOG_SLOT_DONE)
-		__wt_yield();
+		if (++yield_count < 100)
+			__wt_yield();
+		else
+			__wt_sleep(0, 2000);
 	return (0);
 }
 
diff --git a/src/third_party/wiredtiger/src/os_posix/os_mtx_rw.c b/src/third_party/wiredtiger/src/os_posix/os_mtx_rw.c
index 4cda976bea8..b266d652671 100644
--- a/src/third_party/wiredtiger/src/os_posix/os_mtx_rw.c
+++ b/src/third_party/wiredtiger/src/os_posix/os_mtx_rw.c
@@ -95,6 +95,7 @@ __wt_readlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
 	wt_rwlock_t *l;
 	uint64_t me;
 	uint16_t val;
+	int pause_cnt;
 
 	WT_RET(__wt_verbose(
 	    session, WT_VERB_MUTEX, "rwlock: readlock %s", rwlock->name));
@@ -103,8 +104,21 @@ __wt_readlock(WT_SESSION_IMPL *session, WT_RWLOCK *rwlock)
 	l = &rwlock->rwlock;
 	me = WT_ATOMIC_FETCH_ADD8(l->u, (uint64_t)1 << 32);
 	val = (uint16_t)(me >> 32);
-	while (val != l->s.readers)
-		WT_PAUSE();
+	for (pause_cnt = 0; val != l->s.readers;) {
+		/*
+		 * We failed to get the lock; pause before retrying and if we've
+		 * paused enough, sleep so we don't burn CPU to no purpose. This
+		 * situation happens if there are more threads than cores in the
+		 * system and we're thrashing on shared resources. Regardless,
+		 * don't sleep long, all we need is to schedule the other reader
+		 * threads to complete a few more instructions and increment the
+		 * reader count.
+		 */
+		if (++pause_cnt < 1000)
+			WT_PAUSE();
+		else 
+			__wt_sleep(0, 10);
+	}
 
 	++l->s.readers;