[ISSUE-3865] Meaningless connection reset issues caused by low default value for SOMAXCONN

README.md

@@ -90,6 +90,14 @@ To use IoTDB, you need to have:
 1. Java >= 1.8 (1.8, 11, and 15 are verified. Please make sure the environment path has been set accordingly).
 2. Maven >= 3.6 (If you want to compile and install IoTDB from source code).
 3. Set the max open files num as 65535 to avoid "too many open files" error.
+4. (Optional) Set the somaxconn as 65535 to avoid "connection reset" error when the system is under high load.
+    ```
+    # Linux
+    > sudo sysctl -w net.core.somaxconn=65535
+
+    # FreeBSD or Darwin
+    > sudo sysctl -w kern.ipc.somaxconn=65535
+    ```
 
 ## Installation
 

README_ZH.md

@@ -87,6 +87,14 @@ IoTDB的主要特点如下:
 1. Java >= 1.8 (目前 1.8、11和15 已经被验证可用。请确保环变量境路径已正确设置)。
 2. Maven >= 3.6 (如果希望从源代码编译和安装IoTDB)。
 3. 设置 max open files 为 65535，以避免"too many open files"错误。
+4. （可选） 将 somaxconn 设置为 65535 以避免系统在高负载时出现 "connection reset" 错误。 
+    ```
+    # Linux
+    > sudo sysctl -w net.core.somaxconn=65535
+
+    # FreeBSD or Darwin
+    > sudo sysctl -w kern.ipc.somaxconn=65535
+    ```
 
 ## 安装
 

docs/Download/README.md

@@ -71,6 +71,16 @@ Legacy version are available here: [https://archive.apache.org/dist/iotdb/](http
 
 **<font color=red>Attention</font>**:
 
+- Recommended OS parameters
+  * Set the somaxconn as 65535 to avoid "connection reset" error when the system is under high load.
+    ```
+    # Linux
+    > sudo sysctl -w net.core.somaxconn=65535
+
+    # FreeBSD or Darwin
+    > sudo sysctl -w kern.ipc.somaxconn=65535
+    ```
+
 - How to upgrade a minor version (e.g., from v0.11.0 to v0.11.3)?
   * versions which have the same major version are compatible.
   * Just download and unzip the new version. Then modify the configuration files to keep consistent 

docs/zh/Download/README.md

@@ -67,7 +67,17 @@
 
 历史版本下载：[https://archive.apache.org/dist/iotdb/](https://archive.apache.org/dist/iotdb/)
 
-**<font color=red>升级注意事项</font>**:
+**<font color=red>注意事项</font>**:
+
+- 推荐修改的操作系统参数
+  * 将 somaxconn 设置为 65535 以避免系统在高负载时出现 "connection reset" 错误。
+    ```
+    # Linux
+    > sudo sysctl -w net.core.somaxconn=65535
+
+    # FreeBSD or Darwin
+    > sudo sysctl -w kern.ipc.somaxconn=65535
+    ```
 
 - 如何升级小版本 （例如，从 v0.11.0 to v0.11.2)?
   * 同一个大版本下的多个小版本是互相兼容的。

server/src/assembly/resources/conf/iotdb-env.sh

@@ -30,6 +30,33 @@ if [ $max_num -le 65535 ]; then
     fi
 fi
 
+# Set somaxconn to a better value to avoid meaningless connection reset issues when the system is under high load.
+# The original somaxconn will be set back when the system reboots.
+# For more detail, see: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=19f92a030ca6d772ab44b22ee6a01378a8cb32d4
+SOMAXCONN=65535
+case "$(uname)" in
+    Linux)
+        somaxconn=$(sysctl net.core.somaxconn | awk '{print $2}')
+        if [ "$somaxconn" -lt $SOMAXCONN ]; then
+            echo "WARN:"
+            echo "WARN: the value of net.core.somaxconn (=$somaxconn) is too small, please set it to a larger value using the following command."
+            echo "WARN:     sudo sysctl -w net.core.somaxconn=$SOMAXCONN"
+            echo "WARN: The original net.core.somaxconn value will be set back when the os reboots."
+            echo "WARN:"
+        fi
+    ;;
+    FreeBSD | Darwin)
+        somaxconn=$(sysctl kern.ipc.somaxconn | awk '{print $2}')
+        if [ "$somaxconn" -lt $SOMAXCONN ]; then
+            echo "WARN:"
+            echo "WARN: the value of kern.ipc.somaxconn (=$somaxconn) is too small, please set it to a larger value using the following command."
+            echo "WARN:     sudo sysctl -w kern.ipc.somaxconn=$SOMAXCONN"
+            echo "WARN: The original kern.ipc.somaxconn value will be set back when the os reboots."
+            echo "WARN:"
+        fi
+    ;;
+esac
+
 calculate_heap_sizes()
 {
     case "`uname`" in