From 7f00cd226438d3cd91238974346cee624d8920e1 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Wed, 8 Sep 2010 13:26:16 +0200
Subject: [PATCH] Fixed a race condition in VM happening when a key was deleted
 while there was a client waiting for this key to be resumed from swap to
 memory. The client would hang forever.

---
 src/db.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/db.c b/src/db.c
index f380bf6ec..ca520c825 100644
--- a/src/db.c
+++ b/src/db.c
@@ -123,6 +123,11 @@ robj *dbRandomKey(redisDb *db) {
 
 /* Delete a key, value, and associated expiration entry if any, from the DB */
 int dbDelete(redisDb *db, robj *key) {
+    /* If VM is enabled make sure to awake waiting clients for this key:
+     * deleting the key will kill the I/O thread bringing the key from swap
+     * to memory, so the client will never be notified and unblocked if we
+     * don't do it now. */
+    handleClientsBlockedOnSwappedKey(db,key);
     /* Deleting an entry from the expires dict will not free the sds of
      * the key, because it is shared with the main dictionary. */
     if (dictSize(db->expires) > 0) dictDelete(db->expires,key->ptr);