From 97fb8c1133b2512245a30626c44b629d8a7f9afb Mon Sep 17 00:00:00 2001
From: William Yang <mscame@gmail.com>
Date: Fri, 16 Sep 2022 20:18:45 +0200
Subject: [PATCH] perf(TLS): set default sndbuf and recbuf to 4K

Without using default values, sockets will be opened with OS default
buffer sizes. OS default is set by linux aligning to the host memory
size that large memory has larger OS default.

Now more and more user run EMQX in container which has large OS memory
but the container max memory is limited by cgroup that could be very
small amount compared to the OS total memory size.

To eliminate uncertainty, it is better to have the default value set.
---
 CHANGES-4.3.md | 4 +++-
 etc/emqx.conf  | 4 ++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/CHANGES-4.3.md b/CHANGES-4.3.md
index e14b7371e..38f4cbb48 100644
--- a/CHANGES-4.3.md
+++ b/CHANGES-4.3.md
@@ -15,7 +15,9 @@ File format:
 
 - TLS listener memory usage optimization
   new option 'hibernate_after' to hibernate TLS process after idling
-
+- TLS listener default buffer size to 4KB
+  Eliminate uncertainty that the buffer size is set by OS default
+  
 ## v4.3.20
 
 ### Bug fixes
diff --git a/etc/emqx.conf b/etc/emqx.conf
index 19f85a877..7b1bf1ef0 100644
--- a/etc/emqx.conf
+++ b/etc/emqx.conf
@@ -1609,14 +1609,14 @@ listener.ssl.external.ciphers = TLS_AES_256_GCM_SHA384,TLS_AES_128_GCM_SHA256,TL
 ## See: listener.tcp.$name.recbuf
 ##
 ## Value: Bytes
-## listener.ssl.external.recbuf = 4KB
+listener.ssl.external.recbuf = 4KB
 
 ## The TCP send buffer(os kernel) for internal MQTT connections.
 ##
 ## See: listener.tcp.$name.sndbuf
 ##
 ## Value: Bytes
-## listener.ssl.external.sndbuf = 4KB
+listener.ssl.external.sndbuf = 4KB
 
 ## The size of the user-level software buffer used by the driver.
 ##