基于 ShardingSphere 的分布式数据库负载均衡架构搭建实战

💡 MySQL Connector/J 支持配置 autoReconnect 或 tcpKeepAlive，默认不开启；
💡 PostgreSQL JDBC Driver 支持配置 tcpKeepAlive，默认不开启；

💡 客户端不一定支持配置 TCP KeepAlive 或自动重连；
💡 客户端不打算做任何代码或配置调整；
💡 TCP KeepAlive 依赖操作系统实现与配置；

send of 115 bytes failed with errno=104 Connection reset by peer

💡 应用程序对 MySQL 连接的使用已完毕，正常关闭数据库连接；
💡 应用程序与 ShardingSphere-Proxy 的数据库连接受到连接池管理，连接池对空闲超时、或超出最长生命周期的空

💡 应用的定时作业为每小时执行一次，应用没有使用数据库连接池，手动维护了一个数据库连接，提供给定时作业持续使用；
💡 ELB 配置了四层会话保持，会话空闲超时时间为 40 分钟。

user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;

events {
    worker_connections  1024;
}

stream {
    upstream shardingsphere {
        hash $remote_addr consistent;

        server proxy0:3307;
        server proxy1:3307;
    }

    server {
        listen 3306;
        proxy_timeout 1m;
        proxy_pass shardingsphere;
    }
}

version: "3.9"
services:

  nginx:
    image: nginx:1.22.0
    ports:
      - 3306:3306
    volumes:
      - /path/to/nginx.conf:/etc/nginx/nginx.conf

  proxy0:
    image: apache/shardingsphere-proxy:5.3.0
    hostname: proxy0
    ports:
      - 3307

  proxy1:
    image: apache/shardingsphere-proxy:5.3.0
    hostname: proxy1
    ports:
      - 3307

 $ docker compose up -d 
[+] Running 4/4
 ⠿ Network lb_default     Created                                                                                                      0.0s
 ⠿ Container lb-proxy1-1  Started                                                                                                      0.5s
 ⠿ Container lb-proxy0-1  Started                                                                                                      0.6s
 ⠿ Container lb-nginx-1   Started                                                                                                      0.6s

    public     static     void main(String[] args){
        try (Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306?useSSL=false", "root", "root"); Statement statement = connection.createStatement()) {
        log.info(getProxyVersion(statement));
        TimeUnit.SECONDS.sleep(55);
        log.info(getProxyVersion(statement));
        TimeUnit.SECONDS.sleep(65);
        log.info(getProxyVersion(statement));
    }     catch (Exception e) {
        log.error(e.getMessage(), e);
    }
}

    private     static String getProxyVersion(Statement statement)     throws{
        try (ResultSet resultSet = statement.executeQuery("select version()")) {
            if (resultSet.next()) {
                return resultSet.getString(1);
        }
    }
        throw     new UnsupportedOperationException();
}

15:29:12.734 [main] INFO icu.wwj.hello.jdbc.ConnectToLBProxy - 5.7.22-ShardingSphere-Proxy 5.1.1
15:30:07.745 [main] INFO icu.wwj.hello.jdbc.ConnectToLBProxy - 5.7.22-ShardingSphere-Proxy 5.1.1
15:31:12.764 [main] ERROR icu.wwj.hello.jdbc.ConnectToLBProxy - Communications link failure
The last packet successfully received from the server was 65,016 milliseconds ago. The last packet sent successfully to the server was 65,024 milliseconds ago.
        at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
        at com.mysql.cj.jdbc.StatementImpl.executeQuery(StatementImpl.java:1201)
        at icu.wwj.hello.jdbc.ConnectToLBProxy.getProxyVersion(ConnectToLBProxy.java:28)
        at icu.wwj.hello.jdbc.ConnectToLBProxy.main(ConnectToLBProxy.java:21)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet successfully received from the server was 65,016 milliseconds ago. The last packet sent successfully to the server was 65,024 milliseconds ago.
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
        at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
        at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
        at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
        at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:581)
        at com.mysql.cj.protocol.a.NativeProtocol.checkErrorMessage(NativeProtocol.java:761)
        at com.mysql.cj.protocol.a.NativeProtocol.sendCommand(NativeProtocol.java:700)
        at com.mysql.cj.protocol.a.NativeProtocol.sendQueryPacket(NativeProtocol.java:1051)
        at com.mysql.cj.protocol.a.NativeProtocol.sendQueryString(NativeProtocol.java:997)
        at com.mysql.cj.NativeSession.execSQL(NativeSession.java:663)
        at com.mysql.cj.jdbc.StatementImpl.executeQuery(StatementImpl.java:1169)
        ... 2 common frames omitted
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
        at com.mysql.cj.protocol.FullReadInputStream.readFully(FullReadInputStream.java:67)
        at com.mysql.cj.protocol.a.SimplePacketReader.readHeaderLocal(SimplePacketReader.java:81)
        at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:63)
        at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:45)
        at com.mysql.cj.protocol.a.TimeTrackingPacketReader.readHeader(TimeTrackingPacketReader.java:52)
        at com.mysql.cj.protocol.a.TimeTrackingPacketReader.readHeader(TimeTrackingPacketReader.java:41)
        at com.mysql.cj.protocol.a.MultiPacketReader.readHeader(MultiPacketReader.java:54)
        at com.mysql.cj.protocol.a.MultiPacketReader.readHeader(MultiPacketReader.java:44)
        at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:575)
        ... 8 common frames omitted

helm repo add shardingsphere https://apache.github.io/shardingsphere-on-cloud
helm repo update
helm install shardingsphere-proxy shardingsphere/apache-shardingsphere-proxy-charts -n shardingsphere

kubectl run mysql-client --image=mysql:5.7.36 --image-pull-policy=IfNotPresent -- sleep 300
kubectl exec -i -t mysql-client -- mysql -h shardingsphere-proxy-apache-shardingsphere-proxy.shardingsphere.svc.cluster.local -P3307 -uroot -proot