From c6859911190f744f2f133c1d00d5fb67cfcec77d Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Thu, 16 Apr 2009 12:55:47 -0500
Subject: [PATCH] fix self-deadlock in empty IDB entries.

---
 C/dbase.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/C/dbase.c b/C/dbase.c
index 594d711b9..c58eec95f 100644
--- a/C/dbase.c
+++ b/C/dbase.c
@@ -3449,6 +3449,13 @@ lu_recorded(PredEntry *pe) {
       YENV[E_CB] = (CELL) B;
     }
     P = pe->CodeOfPred;
+#if defined(YAPOR) || defined(THREADS)
+    /* avoid holding a lock if we don't have anything in the database */
+    if (P == FAILCODE) {
+      UNLOCK(pe->PELock);
+      PP = NULL;
+    }
+#endif
   }
   if (pe->PredFlags & ProfiledPredFlag) {
     LOCK(pe->StatisticsForPred.lock);