vFabric Elastic Memory for Java (EM4J) 1.3 Release Notes
What's in the Release Notes
These release notes cover the following topics:
What's New in vFabric EM4J 1.3vFabric EM4J 1.3 includes the following changes and new features:
Transparent Heap Sharing
Transparent Heap Sharing (THS) is an EM4J agent feature that proactively cleans and shares Java heap memory when a JVM becomes idle. It allows the hypervisor to move memory to VMs that need additional memory. THS works by slowly inflating a balloon in the heap of an idle JVM, zeroing the memory, and signaling the hypervisor that the memory is available for sharing. THS is as unobtrusive as possible, running only when the JVM is inactive and the heap has recoverable memory. If the application resumes, THS immediately stops, leaving few or no balloon objects behind.
By default, the THS process begins automatically when the EM4J agent detects that the JVM is idle and the heap is in a suitable state to recover memory. This scheduling behavior can be changed using command-line options or, with JMX, the new TransparentHeapSharing MBean. The scheduling mode can be changed from AUTO, the default, to MANUAL, which prevents THS from running unless it is started with JMX, or SCHEDULED, which causes THS to run at a specified time each day.
New Standalone EM4J Distribution
A standalone distribution of the EM4J agent and Console Guest Collector can be downloaded from the VMware download site in ZIP or compressed TAR formats. You can use this installation package to install the CGC or use the EM4J agent with Java workloads other than vFabric tc Server.
Console Guest Collector JMX Enhancements
The Console Guest Collector (CGC) can use the Java Attach API to access JMX in a JVM running on the local host. If the CGC is running as root, it is no longer necessary to add JMX properties to the Java command line to allow the CGC access. If the CGC is running as an unprivileged user, the JMX properties can be specified, or the user can be granted sudo privileges. The CGC helps to configure sudo by logging a message with a sudoers entry needed to grant the required privileges.
EM4J Console UI Improvements
The EM4J plug-in displays data collected by the CGC in the vSphere Web Client 5.1. CGC-monitored JVMs are represented as workload objects in the vSphere Web Client. In this release, workloads are first-class objects integrated into the Web Client Object Navigator. Workloads are accessible as childen of virtual machines, as are networks and datastores.
The Virtual Machine Memory Usage graph, which displays historical workload memory statistics collected by the CGC, is accessed from a VM's Monitor > Performance tab.
The Notes section on the Summary tab for a workload displays the name of the application the JVM is executing if the main class name is recognized. The Console UI recognizes main class names for vFabric Suite components and several other common Java applications. The field is blank if the application cannot be determined.
Updated EM4J Apache Tomcat Integration Kit
The EM4J Apache Tomcat Integration Kit contains files and scripts that add the EM4J agent to an Apache Tomcat installation. The kit has been updated to depend on the standalone EM4J package instead of the elastic-memory template in the vFabric tc Server package. It can be downloaded from the vFabric Suite download Web site, on the Drivers & Tools tab.
The following issues have been identified in this release of vFabric EM4J.
The following issues have been resolved in this release of vFabric EM4J.