From 01eb939a0661c94d22bfddb4841b4975a12dbf7e Mon Sep 17 00:00:00 2001
From: "zhaozhao.zz" <zhaozhao.zz@alibaba-inc.com>
Date: Tue, 25 Jul 2023 21:10:38 +0800
Subject: [PATCH] update monitor client's memory and evict correctly (#12420)
A bug introduced in #11657 (7.2 RC1), causes client-eviction (#8687)
and INFO to have inaccurate memory usage metrics of MONITOR clients.
Because the type in `c->type` and the type in `getClientType()` are confusing
(in the later, `CLIENT_TYPE_NORMAL` not `CLIENT_TYPE_SLAVE`), the comment
we wrote in `updateClientMemUsageAndBucket` was wrong, and in fact that function
didn't skip monitor clients.
And since it doesn't skip monitor clients, it was wrong to delete the call for it from
`replicationFeedMonitors` (it wasn't a NOP).
That deletion could mean that the monitor client memory usage is not always up to
date (updated less frequently, but still a candidate for client eviction).
---
src/networking.c | 2 +-
src/replication.c | 1 +
src/server.c | 6 ++----
3 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/src/networking.c b/src/networking.c
index 56273fc7e..7696e8c28 100644
--- a/src/networking.c
+++ b/src/networking.c
@@ -3808,7 +3808,7 @@ size_t getClientMemoryUsage(client *c, size_t *output_buffer_mem_usage) {
* classes of clients.
*
* The function will return one of the following:
- * CLIENT_TYPE_NORMAL -> Normal client
+ * CLIENT_TYPE_NORMAL -> Normal client, including MONITOR
* CLIENT_TYPE_SLAVE -> Slave
* CLIENT_TYPE_PUBSUB -> Client subscribed to Pub/Sub channels
* CLIENT_TYPE_MASTER -> The client representing our replication master.
diff --git a/src/replication.c b/src/replication.c
index 97e01b64d..885f2b17c 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -610,6 +610,7 @@ void replicationFeedMonitors(client *c, list *monitors, int dictid, robj **argv,
while((ln = listNext(&li))) {
client *monitor = ln->value;
addReply(monitor,cmdobj);
+ updateClientMemUsageAndBucket(monitor);
}
decrRefCount(cmdobj);
}
diff --git a/src/server.c b/src/server.c
index 6815aac3b..838695b88 100644
--- a/src/server.c
+++ b/src/server.c
@@ -917,11 +917,9 @@ void removeClientFromMemUsageBucket(client *c, int allow_eviction) {
* together clients consuming about the same amount of memory and can quickly
* free them in case we reach maxmemory-clients (client eviction).
*
- * Note: This function filters clients of type monitor, master or replica regardless
+ * Note: This function filters clients of type no-evict, master or replica regardless
* of whether the eviction is enabled or not, so the memory usage we get from these
- * types of clients via the INFO command may be out of date. If someday we wanna
- * improve that to make monitors' memory usage more accurate, we need to re-add this
- * function call to `replicationFeedMonitors()`.
+ * types of clients via the INFO command may be out of date.
*
* returns 1 if client eviction for this client is allowed, 0 otherwise.
*/