从零开始手写 dubbo rpc 框架-09-load balance 负载均衡

load balance

当我们有多个服务端时，就需要负载均衡进行选择。

策略

负载均衡的策略有很多，比如随机选择，权重选择，最小负载等等。

实现思路

直接将所有可以选择的服务端列举出来，通过实现对应的策略，选择一个即可。

实现代码

随机选择

此处演示的是非常简单的随机选择策略：

public class RandomBalanceFilter implements RpcFilter {
    @Overridepublic void filter(RpcFilterContext rpcFilterContext) {
    List<RpcChannelFuture> channelFutures = rpcFilterContext.channelFutures();final int size = channelFutures.size();Random random = ThreadLocalRandom.current();int index = random.nextInt(size);rpcFilterContext.channelFuture(channelFutures.get(index));}}

测试代码

注册中心

启动注册中心

服务端

为了验证负载均衡，我们启动两个服务端。

两个服务的端口号不同。

• server-1

public static void main(String[] args) {
    // 启动服务ServiceBs.getInstance().register(ServiceIdConst.CALC, new CalculatorServiceImpl()).registerCenter(ServiceIdConst.REGISTER_CENTER).expose();
}

• server-2

public static void main(String[] args) {
    // 启动服务ServiceBs.getInstance().port(9526).register(ServiceIdConst.CALC, new CalculatorServiceImpl()).registerCenter(ServiceIdConst.REGISTER_CENTER).expose();
}

客户端

为了测试负载均衡，多次执行调用方法。

// 循环 10 次，验证负载均衡。
for(int i = 0; i < 10; i++) {
    CalculateResponse response = calculatorService.sum(request);System.out.println(response);
}

日志

直接通过服务端日志，因为是随机调用，二者收到的请求也基本相同。

• server1

[INFO] [2019-11-01 21:44:15.088] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelActive] - [Server] channel {} connected 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2
[INFO] [2019-11-01 21:44:15.149] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2
[INFO] [2019-11-01 21:44:15.150] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 request: DefaultRpcRequest{seqId='4999d107fd39497691a8427871fa9af1', createTime=1572615855133, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.153] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 response DefaultRpcResponse{seqId='4999d107fd39497691a8427871fa9af1', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.172] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2
[INFO] [2019-11-01 21:44:15.173] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 request: DefaultRpcRequest{seqId='1dcaffd156e444d29d1568bb93325c66', createTime=1572615855169, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.174] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 response DefaultRpcResponse{seqId='1dcaffd156e444d29d1568bb93325c66', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.178] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2
[INFO] [2019-11-01 21:44:15.179] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 request: DefaultRpcRequest{seqId='88f9fd2c9b8f4ce29cc02246529fe475', createTime=1572615855176, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.180] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 response DefaultRpcResponse{seqId='88f9fd2c9b8f4ce29cc02246529fe475', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.184] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2
[INFO] [2019-11-01 21:44:15.184] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 request: DefaultRpcRequest{seqId='51e2a2171e4b4e9987c6d23081c48a0e', createTime=1572615855181, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.185] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 502b73fffec4485c-00001e18-00000002-3d6e1c4a0fd59bed-6a5605d2 response DefaultRpcResponse{seqId='51e2a2171e4b4e9987c6d23081c48a0e', error=null, result=CalculateResponse{success=true, sum=30}}

• server2

[INFO] [2019-11-01 21:44:15.126] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73
[INFO] [2019-11-01 21:44:15.127] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 request: DefaultRpcRequest{seqId='14ee5788e1754575a90ef7ba64340455', createTime=1572615855087, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.130] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 response DefaultRpcResponse{seqId='14ee5788e1754575a90ef7ba64340455', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.159] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73
[INFO] [2019-11-01 21:44:15.160] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 request: DefaultRpcRequest{seqId='a935c347059a477a96b132e41b4b78c1', createTime=1572615855156, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.161] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 response DefaultRpcResponse{seqId='a935c347059a477a96b132e41b4b78c1', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.166] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73
[INFO] [2019-11-01 21:44:15.166] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 request: DefaultRpcRequest{seqId='82778d7d616547e6917f77e6da6e11df', createTime=1572615855163, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.167] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 response DefaultRpcResponse{seqId='82778d7d616547e6917f77e6da6e11df', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.192] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73
[INFO] [2019-11-01 21:44:15.192] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 request: DefaultRpcRequest{seqId='c4e380597fe6419ab12b8928278e4cdb', createTime=1572615855188, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.193] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 response DefaultRpcResponse{seqId='c4e380597fe6419ab12b8928278e4cdb', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.198] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73
[INFO] [2019-11-01 21:44:15.198] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 request: DefaultRpcRequest{seqId='399a2fd2d393413497172510e0651ce9', createTime=1572615855195, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.199] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 response DefaultRpcResponse{seqId='399a2fd2d393413497172510e0651ce9', error=null, result=CalculateResponse{success=true, sum=30}}
[INFO] [2019-11-01 21:44:15.203] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel read start: 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73
[INFO] [2019-11-01 21:44:15.204] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 request: DefaultRpcRequest{seqId='cc1f64281beb4c87bf11eac565609883', createTime=1572615855201, serviceId='calc', methodName='sum', paramTypeNames=[com.github.houbb.rpc.server.facade.model.CalculateRequest], paramValues=[CalculateRequest{one=10, two=20}]}
[INFO] [2019-11-01 21:44:15.205] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffeab09cf-00001d94-00000002-b86e77aa0fd59bd3-dd549b73 response DefaultRpcResponse{seqId='cc1f64281beb4c87bf11eac565609883', error=null, result=CalculateResponse{success=true, sum=30}}