The latest release of JDK Mission Control was just released! Since this is the source release, it may still take a bit of time until the downstream vendors release binary builds of JDK Mission Control 8.2.0. I will try to remember to tweet or say something on the JMC Facebook page once the binaries start showing up.
Here’s what’s new:
Mission Control 8.2 – New and Noteworthy
General
JMC 8.2 – New Release!
This is a new minor release of JDK Mission Control. The JMC application requires JDK 11+ to run, but can still be used to connect to, and parse JFR recordings from, OpenJDK 8u272+ and Oracle JDK 7u40+. It can also still open and visualize flight recordings from JDK 7 and 8.
Eclipse 4.22 support
The Mission Control client is now built to run optimally on Eclipse 2021-06 and later. To install JDK Mission Control into Eclipse, go to the update site (Help | Install New Software…). The URL to the update site will be vendor specific, and some vendors will instead provide an archive with the update site.
Minor bugfixes and improvements
There are 83 fixes and improvements in this release. Check out the JMC 8.2 Result Dashboard (https://bugs.openjdk.java.net/secure/Dashboard.jspa?selectPageId=20804) for more information.
Binary build for Apple ARM
JDK Mission Control is now built for Apple ARM, allowing JMC to be run natively (without Rosetta x86 emulation) on Apple M1.
Core
Parser support for async profiler
Parser support has been added for frame types generated by async profiler, such as Native, C++ and Kernel.
System.gc() rule
There is now a new rule for explicit invocations of System.gc().
Java Flight Recorder (JFR)
Heat map view
A new heat map view has been added, which is handy for seeing when events are taking place. Use Window | Show View | Other…, and select the Heatmap View under Mission Control and click Open to open the view.
Websocket for selections
There is a new websocket API available that pushes stack trace data from selections in the JFR UI as JSON on a user defined port. This allows for programmatic control of the visualization directly in the browser. Tools like observablehq.com can be used to invent new visualizations, or to alter the visualization. To get started, simply go to the Flight Recorder preferences in JMC, and select the Websocket port to use (0 to disable). A set of example visualizations are available here: https://observablehq.com/collection/@cimi/java-mission-control.
Bug Fixes
Area: JFR
Issue: 7403
Synopsis: JFR parser struct types hashcode problem
Some JFR parser struct types were using lazily initialized attributes which happen to be a part of hashCode/equals computations.
Area: JFR
Issue: 7532
Synopsis: Delays in rendering of JMX console graphs
Sometimes the updates of the JMX console graphs would be severely delayed on MacOS. This is now fixed.
Area: JFR
Issue: 7068
Synopsis: JfrRecordingTest (uitest) hangs on the automated analysis page
Trying to run uitests on Fedora hangs on JfrRecordingTest. This was fixed after the Eclipse platform update.
Known Issues
Area: General
Issue: 4270
Synopsis: Hibernation and time
After the bugfix of https://bugs.openjdk.java.net/browse/JDK-6523160 in JDK 8, the RuntimeMXBean#getUptime() attribute was re-implemented to mean “Elapsed time of JVM process”, whilst it previously was implemented as time since start of the JVM process. The uptime attribute is used by JMC, together with RuntimeMXBean#getStartTime(), to estimate the actual server time. This means that time stamps, as well as remaining time for a flight recording, can be wrong for processes on machines that have been hibernated.
Area: JFR
Issue: 7071
Synopsis: JMC can’t attach to jlinked JVMs
This one is still under investigation, but it seems JMC can’t attach to certain jlinked images.
Area: JFR
Issue: 7003
Synopsis: The graph and flame graph view does not work on Windows
This is due to a problem with the Windows based browser component in SWT. We’re hoping for a fix in the component for a future version of the Eclipse platform.