Add the number of locks acquired by a transaction to its weight when

choosing the lightest transaction to kill when a deadlock occurs.
This fixes Bug#21293 partially.

Approved by:	Heikki

include/trx0trx.h

@@ -371,6 +371,17 @@ trx_is_interrupted(
 #define trx_is_interrupted(trx) FALSE
 #endif /* !UNIV_HOTBACKUP */
 
+/***********************************************************************
+Compares the "weight" (or size) of two transactions. The weight of one
+transaction is estimated as the number of altered rows + the number of
+locked rows. */
+
+int
+trx_weight_cmp(
+/*===========*/
+			/* out: <0, 0 or >0; similar to strcmp(3) */
+	trx_t*	a,	/* in: the first transaction to be compared */
+	trx_t*	b);	/* in: the second transaction to be compared */
 
 /* Signal to a transaction */
 struct trx_sig_struct{

lock/lock0lock.c

@@ -3357,8 +3357,8 @@ lock_deadlock_recursive(
 					return(LOCK_VICTIM_IS_START);
 				}
 
-				if (ut_dulint_cmp(wait_lock->trx->undo_no,
-						  start->undo_no) >= 0) {
+				if (trx_weight_cmp(wait_lock->trx,
+						   start) >= 0) {
 					/* Our recursion starting point
 					transaction is 'smaller', let us
 					choose 'start' as the victim and roll

trx/trx0trx.c

@@ -1773,6 +1773,24 @@ trx_print(
 	}
 }
 
+/***********************************************************************
+Compares the "weight" (or size) of two transactions. The weight of one
+transaction is estimated as the number of altered rows + the number of
+locked rows. */
+
+int
+trx_weight_cmp(
+/*===========*/
+			/* out: <0, 0 or >0; similar to strcmp(3) */
+	trx_t*	a,	/* in: the first transaction to be compared */
+	trx_t*	b)	/* in: the second transaction to be compared */
+{
+#define TRX_WEIGHT(t)	\
+	ut_dulint_add((t)->undo_no, UT_LIST_GET_LEN((t)->trx_locks))
+
+	return(ut_dulint_cmp(TRX_WEIGHT(a), TRX_WEIGHT(b)));
+}
+
 /********************************************************************
 Prepares a transaction. */