Clarify comment in change fixing #4323.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/slowlog.c b/src/slowlog.c
index a95147153..32ec4374c 100644
--- a/src/slowlog.c
+++ b/src/slowlog.c
@@ -75,8 +75,12 @@ slowlogEntry *slowlogCreateEntry(client *c, robj **argv, int argc, long long dur
             } else if (argv[j]->refcount == OBJ_SHARED_REFCOUNT) {
                 se->argv[j] = argv[j];
             } else {
-                /* Duplicate a string object,
-                 * avoid memory leak for lazyfree. */
+                /* Here we need to dupliacate the string objects composing the
+                 * argument vector of the command, because those may otherwise
+                 * end shared with string objects stored into keys. Having
+                 * shared objects between any part of Redis, and the data
+                 * structure holding the data, is a problem: FLUSHALL ASYNC
+                 * may release the shared string object and create a race. */
                 se->argv[j] = dupStringObject(argv[j]);
             }
         }