WT-2766 Don't sweep LAS cache when aren't making progess in eviction (#2918)

1 files changed, 17 insertions, 2 deletions

diff --git a/src/conn/conn_sweep.c b/src/conn/conn_sweep.c
index 5d24ea61607..67c3a734801 100644
--- a/src/conn/conn_sweep.c
+++ b/src/conn/conn_sweep.c
@@ -258,10 +258,12 @@ __sweep_server(void *arg)
 	WT_DECL_RET;
 	WT_SESSION_IMPL *session;
 	time_t now;
+	uint64_t last_las_sweep_id, oldest_id;
 	u_int dead_handles;
 
 	session = arg;
 	conn = S2C(session);
+	last_las_sweep_id = WT_TXN_NONE;
 
 	/*
 	 * Sweep for dead and excess handles.
@@ -278,9 +280,22 @@ __sweep_server(void *arg)
 		/*
 		 * Sweep the lookaside table. If the lookaside table hasn't yet
 		 * been written, there's no work to do.
+		 *
+		 * Don't sweep the lookaside table if the cache is stuck full.
+		 * The sweep uses the cache and can exacerbate the problem.
+		 * If we try to sweep when the cache is full or we aren't
+		 * making progress in eviction, sweeping can wind up constantly
+		 * bringing in and evicting pages from the lookaside table,
+		 * which will stop the WT_CACHE_STUCK flag from being set.
 		 */
-		if (__wt_las_is_written(session))
-			WT_ERR(__wt_las_sweep(session));
+		if (__wt_las_is_written(session) &&
+		    !F_ISSET(conn->cache, WT_CACHE_STUCK)) {
+			oldest_id = __wt_txn_oldest_id(session);
+			if (WT_TXNID_LT(last_las_sweep_id, oldest_id)) {
+				WT_ERR(__wt_las_sweep(session));
+				last_las_sweep_id = oldest_id;
+			}
+		}
 
 		/*
 		 * Mark handles with a time of death, and report whether any