2 Documentation Errata

This chapter describes changes, enhancements, and corrections made to the Oracle Coherence documentation library for the 3.7 release. This chapter describes the following issues:

The Coherence documentation library can be found at the following URL:

https://download.oracle.com/docs/cd/E18686_01/index.htm

JVM Heap Size Recommendations

The "Sizing Your Heap" section in the Coherence Administration Guide recommends (on Oracle 1.6 JVM or JRockit) a conservative 4GB heap size. The recommendation is based on throughput, latency, and stability for most applications. However, larger heaps, up to 20GB, are suitable for some applications where the simplified management of fewer, larger JVMs outweighs the performance benefits of many smaller JVMs. A core-to-heap ratio of roughly 1 core: 2 GB is ideal, with some leeway to manage more GB per core (3 or even 4 GB). Every application is different and garbage collection (GC) times must be monitored accordingly.

TCMP-Supported Communication Protocols and Schemes

The "Understanding TCMP" section in the Oracle Coherence Developer's Guide does not provide a complete list of the communication protocols and schemes that are supported by TCMP. TCMP can be configured to use:

  • A combination of UDP/IP multicast and UDP/IP unicast. This is the default configuration.

  • UDP/IP unicast only (that is, no multicast). See "Disabling Multicast Communication" for details. This configuration is used for network environments that do not support multicast or where multicast is not optimally configured.

  • TCP/IP only (no UDP/IP multicast or UDP/IP unicast). See "Using the TCP Socket Provider" for details. This configuration is used for network environments that favor TCP/IP.

  • SSL over TCP/IP. See "Using the SSL Socket Provider" for details. This configuration is used for network environments that require highly secure communication between cluster members.