Cassandra Java驱动程序协议版本和连接限制不匹配

问题描述

我正在使用Java驱动程序版本：2.1.4

Cassandra版本：dsc-cassandra-2.1.10

cql的输出给出以下内容

I am using java driver version: 2.1.4
Cassandra version: dsc-cassandra-2.1.10
Output from cql gives the following

cqlsh 5.0.1 | Cassandra 2.1.10 | CQL spec 3.2.1 | Native protocol v3

我是协议V3。但是，当我尝试将其设置为每个连接超过128个请求时，它将引发异常。这似乎是V2中的限制。解释如下：

I am protocol V3. But it throws an exception when I try to set it to more than 128 requests per connection. This seems to be a restriction in V2. Explained below:

以下代码块：

PoolingOptions poolingOptions = new PoolingOptions();
poolingOptions.setCoreConnectionsPerHost(HostDistance.LOCAL, 8);

Cluster cluster = Cluster.builder()
                         .addContactPoints(x.x.x.x)
                         .withPoolingOptions(poolingOptions)
                         .withProtocolVersion(ProtocolVersion.V3)
                         .build();

System.out.println("Protocol version = "+myCurrentVersion);
System.out.println("LOCAL CORE = "+poolingOptions.getCoreConnectionsPerHost(HostDistance.LOCAL));
System.out.println("LOCAL MAX = "+poolingOptions.getMaxConnectionsPerHost(HostDistance.LOCAL));
System.out.println("Max sim requests = "+poolingOptions.getMaxSimultaneousRequestsPerConnectionThreshold(HostDistance.LOCAL));
System.out.println("Max sim requests per host = "+poolingOptions.getMaxSimultaneousRequestsPerHostThreshold(HostDistance.LOCAL));

 poolingOptions
.setMaxSimultaneousRequestsPerHostThreshold(HostDistance.LOCAL, 3000);

 poolingOptions
.setMaxSimultaneousRequestsPerConnectionThreshold(HostDistance.LOCAL, 128);

System.out.println("LOCAL CORE = "+poolingOptions.getCoreConnectionsPerHost(HostDistance.LOCAL));
System.out.println("LOCAL MAX = "+poolingOptions.getMaxConnectionsPerHost(HostDistance.LOCAL));
System.out.println("Max sim requests = "+poolingOptions.getMaxSimultaneousRequestsPerConnectionThreshold(HostDistance.LOCAL));
System.out.println("Max sim requests per host = "+poolingOptions.getMaxSimultaneousRequestsPerHostThreshold(HostDistance.LOCAL));

输出为：

Protocol version = V3
LOCAL CORE = 1
LOCAL MAX = 8
Max sim requests = 100
Max sim requests per host = 1024
Exception in thread "main" java.lang.IllegalArgumentException: Max simultaneous requests per connection for LOCAL hosts must be in the range (0, 128)
    at com.datastax.driver.core.PoolingOptions.checkRequestsPerConnectionRange(PoolingOptions.java:370)
    at com.datastax.driver.core.PoolingOptions.setMaxSimultaneousRequestsPerConnectionThreshold(PoolingOptions.java:175)
    at ca.txio.pricehistoryservice.main.ConnectionOptionTest.main(ConnectionOptionTest.java:38)

根据Cassandra文档

和

According to the Cassandra documentationhttps://docs.datastax.com/en/developer/java-driver/2.1/manual/native_protocol/andhttp://docs.datastax.com/en/developer/java-driver/2.1/manual/pooling/

我是协议V3。但是为什么我每个连接限制为128个请求。这似乎是V2中的限制。有人可以解释一下如何找到我的实际版本，如果确实是V3，为什么我不能同时建立128个以上的并行连接？

I am protocol V3. But why am I restricted to 128 requests per connection. This seems to be a restriction in V2. Could someone please explain how to find what version I actually am, and if indeed V3, why can't I have more than 128 simultaneous connections?

推荐答案

对于ProtocolVersion＃V3或更高版本，每个连接最多有32768个请求，并且该池默认为固定大小1。通常，通过允许每个连接同时发出更多请求来提高最大容量（ setMaxRequestsPerConnection （HostDistance，int））

With ProtocolVersion#V3 or above, there are up to 32768 requests per connection, and the pool defaults to a fixed size of 1. You will typically raise the maximum capacity by allowing more simultaneous requests per connection (setMaxRequestsPerConnection(HostDistance, int))

参考：

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