May 2015 Summaries

The Java Driver team has released version 2.0.10 with new features, improvements and bugfixes. Highlights include Speculative Executions for protection against bad read latencies, QueryLogger for logging queries executed by the driver, PerHostPercentileTracker for recording latency histograms, and Netty shading for customizing the underlying layer of the driver. Automatic query paging has been made possible with JAVA-550, while BoundStatement class now includes get*() methods to retrieve typed CQL values. The driver can also report information about token distribution across the ring, useful for Hadoop and Spark applications interacting with Cassandra tables. Connection pool resizing algorithm has been improved, and asynchronous parallel connection pool initialization is introduced. JAVA-425, which caused aggressive behavior regarding driver read timeouts, has been reverted. New API to check schema agreement between peers and changes in thread naming are also included.

Nagle's algorithm, originally designed for misbehaving applications that write multiple small messages at once, can result in large messages being fragmented and additional delays based on fixed timers instead of network conditions. Disabling Nagle's algorithm is a requirement for some performance-sensitive applications to achieve predictable message latency with fewer outliers. Coalescing network messages at the application level has been introduced as an alternative solution, which can be beneficial in virtualized environments where packet processing throughput may be limited compared to task processing within a VM. Cassandra supports coalescing network messages between nodes and for responses to clients, with different strategies available such as fixed, moving average, time horizon, and disabled. Coalescing message routing has been improved by 8789, which changes how messages are routed between nodes based on size. The impact of coalescing is highly dependent on the configuration and workload, so it's recommended to conduct your own measurements when considering its implementation.