Merge pull request #1610 from wiredtiger/log-yields

Avoid yielding in logging: it causes problems with large numbers of threads

2 files changed, 16 insertions, 5 deletions

diff --git a/src/log/log.c b/src/log/log.c
index a173a829436..5e1256aec07 100644
--- a/src/log/log.c
+++ b/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/log/log_slot.c b/src/log/log_slot.c
index cb959f28bd7..611587aaa8e 100644
--- a/src/log/log_slot.c
+++ b/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);
 }