JDK Mission Control 9.0.0 Released!

2024-03-22 - By Marcus

The 9.0.0 GA release of JDK Mission Control was just tagged in the JMC repo at GitHub! 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 9.0.0. I will try to remember to tweet or say something on the JMC Facebook page once the binaries start showing up.

Mission Control 9.0 – New and Noteworthy

General

JMC 9 – New Release!
This is the latest (2024) major release of JDK Mission Control. JMC 9 requires JDK 17+ to run and introduces several new features, enhancements, and bug fixes. This version continues to support connecting to, and parsing JFR recordings from, OpenJDK 8u272+ and Oracle JDK 7u40+, and can open and visualize flight recordings from JDK 7 and 8. JDK Mission Control is available for Windows (x86_64), Mac OS X (ARM and x86_64), and Linux (ARM and x86_64).

Eclipse 4.30 support
The Mission Control client is now built to run optimally on Eclipse 2023-12 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.

Support for Linux/aarch64
JMC 9 is now built for Linux aarch64.

Support for dark mode
JMC 9 now supports dark mode. Go to Preferences, General | Appearance, and select the Dark theme to enable.

Minor bugfixes and improvements
There are 118 fixes and improvements in this release. Check out the JMC 9.0 Result Dashboard for more information.

Add user configuration for local JVM refresh interval
Previously the JVM Browser checked every 5000 ms for new JVMs. This can now be configured.

Core

Better JFR parser performance
Multiple efforts have been made to reduce allocations in the JMC parser, including: reduced allocation of Doubles, reduced allocation rate in ParserStats. Also, when duration events aren’t ordered by their end time (e.g. events which stack so that the last event finishes first, or file reads with overlaps) `DisjointBuilder.add` can be slow because of the linear search for the lane, and then a linear time reordering. This has been improved with a binary search.

Support checkpoint event sizes beyond u4 limit
The JMC JFR parser now support checkpoint event sizes beyond the u4 limit.

Move non-Eclipse dependent classes from org.openjdk.jmc.ui.common to org.openjdk.jmc.common
There were a number of classes previously in jmc.ui.common that would be a great asset to the core distribution (and the third-party applications that consume jmc-core), and these classes now live in jmc.common. Please see JMC-7308 for further information.

Move rjmx bundle from application to core
The rjmx classes and related services (FlightRecorderService) are now exposed for third-party application usage. Please see JMC-7069 for further information.

Move org.openjdk.jmc.flightrecorder.configuration bundle from application to core
The org.openjdk.jmc.flightrecorder.configuration bundle contains many classes useful for working with jfr, and are now available in core. Please see JMC-7307 for further information.

Java Flight Recorder (JFR)

The Event Browser now supports searching and showing event type ids
Searching in the search bar now also searches event type IDs, and there is also a (by default hidden) column that makes it easy to show the event type IDs for the shown events.

Add support for enabling jfr on native images
Previously JMC was unable to start flightrecorder on a graalvm native image, even if there is built-in jfr support. This has now been fixed.

Java based flamegraph visualization
The previous flamegraph visualization takes place in an embedded browser component (provided by the Eclipse platform), unfortunately this approach has some drawbacks, the first being a bit slow. This view is now using a Java (Swing) based flamegraph library. Also, the flame graph model creation performance have been improved.

Visualization and Rule for FileChannel.force()
The File I/O page has been updated to show force related information. There are two new columns added – Force Count and Update Metadata. Both are hidden by default and can be enabled by right clicking the table. The chart will also include a File Force row. There is a preference setting for the associated file force rule, where the peak duration warning limit can be set. See JMC PR#533 for more information.

Rule that checks on G1 pause time target compliance
New rule that looks at the pause time target and compares it to the actual pauses.

Rule that looks at finalization statistics
JDK 18 comes with a FinalizationStatistics event that helps users find where in their application finalizers are run. This is important as finalization has been deprecated for removal in a future release. For more information about finalization and its flaws, see https://openjdk.java.net/jeps/421. Even if an application doesn’t implement any finalize() methods, it may rely on third-party libraries that does. Static analysis of third-party libraries using “jdeprscan –for-removal” can be used to list those classes, but it will not tell if they are being used. For example, an application may be missing a call to a close() method, so the resource is cleaned up by the finalizer, which is sub-optimal.

Rule that detects GC Inverted Parallelism
Rule inspired by the “Inverted Parallelism” analysis in Garbagecat. See JMC-8144 for more information.

Support for the new JPLIS agent events
There is now a new page and rule for loaded JPLIS agents. See JMC-8054 for more information.

Twitter plug-in removed
Due to changes in APIs and cost of maintenance, the Twitter plug-in has been removed.

Bug Fixes

Area: Agent
Issue: 8045
Synopsis: retransformClasses() doesn’t re-transform all needed classes

The retransformClasses() methods in Agent and AgentController use Class.forName() to try to get the class objects of classes needed to re-transform. This obviously doesn’t work for classes loaded by classloaders different from the one which loads the agent. Those classes would be instrumented if they were loaded after their event probes were defined the AgentController. But when loaded earlier they would not be instrumented. This has been fixed.

Area: Agent
Issue: 8048
Synopsis: Agent throws exceptions on missing or empty descriptions

When the description of an event or value is empty or missing, the agent fails with exceptions. This has now been fixed.

Area: Console
Issue: 8154
Synopsis: Some JMX attributes are missing unit specifications in the Console

The missing unit specifications have now been added.

Area: Core
Issue: 8063
Synopsis: IMCFrame Type cache not synchronized

The type cache used in the IMCFrame Type inner class wasn’t synchronized and could cause a concurrent modification exception during e.g. JFR parsing. This has been fixed.

Area: Core
Issue: 8156
Synopsis: JfrRulesReport.printReport does not respect verbosity for text and json

The verbosity flag for text and json reports didn’t work. This has been fixed.

Area: Core
Issue: 8041
Synopsis: JfrRulesReport json reports produce incomplete results

While generating JFR Rules Reports in json format, the results were incomplete. The components “message” and “detailedMessage” were not populated. This has been fixed.

Area: JFR
Issue: 7885
Synopsis: Graphical rendering of dependency view fails due to heap memory drain

Also JMC-7496. The dependency view drains the heap memory and causes out-of-memory exceptions and performance delays. This has been improved.

Known Issues

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 view, heatmap view and dependency 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.

JDK Mission Control 8.3.0 Released!

2022-11-22 - By Marcus

The latest release of JDK Mission Control was recently released! Since I am a bit late with this blog, there are already some binary releases available, for example:

Eclipse Mission Control:
https://adoptium.net/jmc/

Zulu Mission Control:
https://www.azul.com/products/components/azul-mission-control/

Mission Control 8.3 – New and Noteworthy

General

JMC 8.3 – 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. JDK Mission Control is built for Windows (x86_64), Mac OS X (ARM and x86_64), as well as Linux (x86_64).

jmc[1]

Eclipse 4.24 support
The Mission Control client is now built to run optimally on Eclipse 2022-06 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.

eclipse[1]

Minor bugfixes and improvements
There are 51 fixes and improvements in this release. Check out the JMC 8.3 Result Dashboard (https://bugs.openjdk.org/secure/Dashboard.jspa?selectPageId=21205) for more information.

Core

Parser improvements
The performance of the FastAccessNumberMap has been improved for sparse values.

Java Flight Recorder (JFR)

Dependency View
There is a new view for visualizing call dependencies. There are two modes of operation in the view, chord diagram and edge bundling. In the edge bundling visualization, hover over packages to see dependencies highlighted in colors: green means that methods in the linked package is called by methods in the package being hovered over, yellow means that methods in the linked package are calling mathods in the package being hovered over. Red means that methods in the packages are calling each other. To show the Dependency View, go to Window | Show View | Other… and select the Dependency View under the Mission Control folder.

Graph Pruning
The graph view in JMC can now be pruned to focus on the most impactful nodes. Select the target number of nodes, and the visualization will show at most that many number of nodes.

Selectable Attribute
It is now possible to select which attribute to use for the weights in the trace view and the flame graph view.

Parser improvement
The parser now supports parsing events with char fields.

Bug Fixes

Area: General
Issue: 7813
Synopsis: Unable to open Help page in macOS M1 when JMC started with JDK11

The help page was inaccessible, throwing an error on macOS M1 when JMC is run on JDK 11.0.16. This is now fixed.

Area: General
Issue: 7321
Synopsis: Unable to view JMC Help Contents (HTTP ERROR 500 ) when booted with JDK 17 or higher

The help page was inaccessible, throwing an error, when running on JDK 17+. This is now fixed.

Area: JFR
Issue: 7812
Synopsis: Unable to open links from Automated Result analysis page

Links in the results of the automated analysis results would not open properly on Linux and Mac OS X. Now they do open in situ.

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: General
Issue: 7953
Synopsis: Unable to install JMC Plugins on Eclipse 4.25

Because of updates to the naming of certain platform dependencies in Eclipse 4.25 (e.g. JUnit 5 bundles now have name of the form junit-* instead of Orbit variants org.junit.*), it will no longer be possible to install the plug-in version of JMC into Eclipse 4.25+. This will be resolved in a later version of JMC. A workaround for now is to build JMC from the mainline (9.0 EA), and installing the plug-in version from the resulting update site archive.

Area: JFR
Issue: 7947
Synopsis: JMC crashes while performing flight recording on MacOS 13.0_x64

JMC can crash when completing a recording on MacOS 13.0 on x64. It seems to be related to running JavaScript in the Browser component. Eclipse is investigating the issue here.

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, flame graph view, heatmap view and dependency 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.

TL;DR

There is a new version of JMC out. Have fun! Smile

JDK Mission Control 8.2.0 Released!

2022-03-20 - By Marcus

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

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.

JMC Core Now on Maven Central!

2021-08-03 - By Marcus

Good news! The JDK Mission Control core library bundles are now available on Maven Central, making it easier than ever to use things like the the JMC JDK Flight Recorder parser to transparently parse and extract information from flight recordings ranging from Oracle JDK 7 and up to the very latest versions of OpenJDK.

I have updated my JShell example so that you can see an example of them being used.

For just using the parser, you will typically need the common and flightrecorder bundles. If you also need the rules engine, you add flightrecorder.rules, and if you want the base set of heuristics for the jdk, also add flightrecorder.rules.jdk.

For example:

	<properties>
		<jmc.version>8.0.1</jmc.version>
	</properties>
	<dependencies>
		<dependency>
			<groupid>org.openjdk.jmc</groupid>
			<artifactid>common</artifactid>
			<version>${jmc.version}</version>
		</dependency>
		<dependency>
			<groupid>org.openjdk.jmc</groupid>
			<artifactid>flightrecorder</artifactid>
			<version>${jmc.version}</version>
		</dependency>
		<dependency>
			<groupid>org.openjdk.jmc</groupid>
			<artifactid>flightrecorder.rules</artifactid>
			<version>${jmc.version}</version>
		</dependency>
		<dependency>
			<groupid>org.openjdk.jmc</groupid>
			<artifactid>flightrecorder.rules.jdk</artifactid>
			<version>${jmc.version}</version>
		</dependency>
	</dependencies>

Finally! 🙂

JMC 8 Binary Releases!

2021-03-17 - By Marcus

Two binary releases of JMC 8 are now available:

Since I could not find the project provided release notes at any of the vendor sites, I’ve taken the liberty of reproducing them below.

Mission Control 8.0 – New and Noteworthy

General

JMC 8.0 – Major New Release!
This is a major new release of Java Mission Control. All binary build of the JMC application using the Eclipse 2020-09 platform will now require JDK 11+ to run, but can be used with OpenJDK 8u272+ and Oracle JDK 7u40+. It can also open and visualize flight recordings from JDK 7 and 8.

Eclipse 4.16 support
The Mission Control client is now built to run optimally on Eclipse 2020-06 and later. To install Java 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.

JOverflow in the Base Distribution
JOverflow is now part of the base distribution of Mission Control, and has been converted to SWT. It also has a brand new TreeMap visualization of the heap occupied by type. To open the new view, go to Window | Show view | Other… and start typing JOverflow, and select JOverflow TreeMap.

Minor bugfixes and improvements
There are over two hundred fixes and improvements in this release. Check out the JMC 8 Result Dashboard (https://bugs.openjdk.java.net/secure/Dashboard.jspa?selectPageId=19536″) for more information.

Java Flight Recorder (JFR)

Flame Graph View Improvements
The Flame Graph View is now available in the standard perspective. It can now be configured to be rendered either as an icicle graph or a flame graph, and the tool tips have been improved. Click on anything representing a selection of events to get the aggregate of stack traces represented by that selection rendered in the Flame Graph View.

New Graph View
An early access version of a Graph View is now available. The Graph View will show a directed graph where the individual methods are nodes in the graphs, and the edges will represent calls from one method to another. The size of the node will represent the “self” contribution, and the thickness of an edge will correlate with the number of calls from one method to another in the events. To open up the graph view, go to Window | Show view | Other…, then select Mission Control / Graph View. Once the Graph View has opened, it can be docked where you want it to be, or dragged out into a new top level window which can be handled by your window manager. Currently there is no graph pruning, and large graph will take a very long time to layout and render, during which the UI will freeze. Therefore we’ve imposed a user configurable limit on the number of nodes a graph can have for now.

Predecessors and Successors
The predecessors and successors tabs have been brought back to the Method Profiling page. This means that it is now easy to select a method and easily see wherever that method was called from, and to see what was then called from that method. This is a temporary solution until we have a separate Butterfly/Sandwich view where any selection of a method in a set of events can be rendered in a separately configured view.

JMC Agent

Agent 1.0.0
This is the first version where we build and release the JMC agent. The JMC agent is a byte code instrumentation agent, providing an easy way to declaratively generate JFR events from most methods, even methods for which the source code is not available. Either configure the agent with an XML configuration file, or use the MBean to dynamically change the instrumentation whilst the application is running.

Converter Functions
Now any public static method can be used to convert objects of a specific type to one of the types supported by flight recorder. The converter to use must be explicitly declared per recorded data.

Bug Fixes

Area: JFR
Issue: 5734
Synopsis: Overflow in stacktrace tooltips fixed

On Mac, the tooltips shown for the stacktraces could overflow. This is now fixed.

Known Issues

Area: General
Issue: 4270
Synopsis: Hibernation and time

Area: JFR
Issue: 7122
Synopsis: Rules evaluation never complete

Sometimes the rules evaluation may never complete for the GC rules.

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: 7068
Synopsis: JfrRecordingTest (uitest) hangs on the automated analysis page

Trying to run uitests on Fedora hangs on JfrRecordingTest.

Area: JFR
Issue: 7007
Synopsis: Unable to edit run configurations for eclipse project after installing JMC plugin

Avoid installing the experimental JMC launcher plug-in into Eclipse until this problem has been resolved.

Area: JFR
Issue: 7003
Synopsis: The graph view does not work on Windows

This is due to a bug in the chromium browser plug-in used by JMC on Windows. See the issue for more information.

Area: JFR
Issue: 6265
Synopsis: JMC crashes with Webkit2+GTK 4

See the issue for more information.

Area: JFR
Issue: 6265
Synopsis: JMC crashes with Webkit2+GTK 4

See the issue for more information.

Area: JFR
Issue: 5412
Synopsis: Dragging and dropping a JFR file into an open analysis page does not work

The expected behaviour would be to open the recording whenever a file is dropped in the editor area, but the behaviour will be defined by the embedded browser component, and not very useful.

Fetching and Building Mission Control 8+

2019-11-25 - By Marcus

As described in a previous post, Mission Control is now on GitHub. Since this alters how to fetch and build OpenJDK Mission Control, this is an updated version of my old post on how to fetch and build JMC from version 8 and up.

Getting Git

First step is to get Git, the SCM used for OpenJDK Mission Control. Installing Git is different for different platforms, but here is a link to how to get started:

https://git-scm.com/book/en/v2/Getting-Started-Installing-Git

Installing the Skara Tooling (Optional)

This is an optional step, making it easier if you want to contribute to Mission Control:

https://hirt.se/blog/?p=1186

Cloning the Source

Once Git is installed properly, getting the source is as easy as cloning the jmc repo. First change into the directory where you want to check out jmc. Then run:

git clone https://github.com/openjdk/jmc.git

Getting Maven

Since you probably have some Java experience, you probably already have Maven installed on your system. If you do not, you now need to install it. Simply follow the instructions here:

https://maven.apache.org/install.html

Building Mission Control

First we need to ensure that Java 8 is on our path. Some of the build components still use JDK 8, so this is important.

java –version

This will show the Java version in use. If this is not a Java 8 JDK, change your path. Once done, we are now ready to build Mission Control. Open up two terminals. Yep, two!

In the first one, go to where your cloned JMC resides and type in and execute the following commands (for Windows, replace the dash (/) with a backslash (\)):

cd releng/third-party
mvn p2:site
mvn jetty:run

Now, leave that terminal open with the jetty running. Do not touch.

In the second terminal, go to your cloned jmc directory. First we will need to build and install the core libraries:

cd core
mvn install

Next run maven in the jmc root:

mvn clean package

JMC should now be building. The first time you build Maven will download all of the third party dependencies. This will take some time. Subsequent builds will be less painful. On my system, the first build took 6:01 min. The subsequent clean package build took 2:38.

Running Mission Control

To start your recently built Mission Control, run:

Windows

target\products\org.openjdk.jmc\win32\win32\x86_64\jmc.exe -vm %JAVA_HOME%\bin

Mac OS X

target/products/org.openjdk.jmc/macosx/cocoa/x86_64/JDK\ Mission\ Control.app/Contents/MacOS/jmc -vm $JAVA_HOME/bin

Contributing to JDK Mission Control

To contribute to JDK Mission Control, you need to have signed an Oracle Contributor Agreement. More information can be found here:

http://openjdk.java.net/contribute/

Don’t forget to join the dev list:

http://mail.openjdk.java.net/mailman/listinfo/jmc-dev

We also have a Slack (for contributors), which you can join here:

https://join.slack.com/t/jdkmissioncontrol/signup

More Info

For more information on how to run tests, use APIs etc, there is a README.md file in the root of the repo. Let me know in the comments section if there is something you think I should add to this blog post and/or the README!

Using the Skara Tooling

2019-11-15 - By Marcus

I’m writing this for myself as much as I’m writing this to share. After only a day of using JMC with Skara, I’ve fallen in love with it. I spend less time painstakingly putting together review e-mails, copying and pasting code to comment on certain lines of code, cloning separate repos to do parallel work efficiently, setting up new workspaces for the these repos etc. Props to the Skara team for saving me time by cutting out a big chunk of the stuff not related to coding and a whole lot of ceremony.

Note that the Skara tooling can be used outside of the scope of OpenJDK – git sync alone is a good reason for why everyone who wants to reduce ceremony can benefit from the Skara tooling.

So, here are a few tips on how to get started:

Clone Skara:
git clone https://github.com/openjdk/skara
Build it:
gradlew (win) or sh gradlew (mac/linux)
Install it:
git config --global include.path "%CD%/skara.gitconfig" (win) or git config --global include.path "$PWD/skara.gitconfig" (mac/linux)
Set where to sync your forks from:
git config --global sync.from upstream

For folks on Red Hat distros, 2 and 3 can be replaced by make install. For more information on the installation, see the Skara wiki.

Some Examples

To sync your fork with upstream and pull the changes:
git sync --pull

Note: if the sync fails with the error message “No remote provided to fetch from, please set the –from flag”, remember to set the remote for your repo, e.g.
git remote add upstream https://github.com/openjdk/jmc

To list the open PRs:
git pr list

To create a PR:
git pr create

To push your committed changes in your branch to your fork, creating the remote branch:
git publish

JMC Workflow

Below is the typical work-flow for JMC.

First ensure that you have a fork of JMC. Either fork it on github.com, or on the command line:
git fork https://github.com/openjdk/jmc jmc

You typically just create that one fork and stick with it.

(Optional) Sync up your fork with upstream:
git sync --pull
Create a branch to work on, with a name you pick, typically related to the work you plan on doing:
git checkout –b <branchname>
Make your changes / fix your bug / add amazing stuff
(Optional) Run jcheck locally:
git jcheck local
Push your changes to the new branch on your fork:
git publish (which is pretty much git push --set-upstream origin <branchname>)
Create the PR, either on GitHub, or from the command line:
git pr create

Summary / TL;DR

I ❤️ Skara

Mission Control is Now Officially on GitHub!

2019-11-14 - By Marcus

Since this morning, the JDK Mission Control (JMC) project has gone full Skara! This means that the next version (JMC 8.0) will be developed over at GitHub.

To contribute to JDK Mission Control, you (or the company you work for) need to have signed an OCA, like for any other OpenJDK-project. If you already have an OpenJDK username, you can associate your GitHub account with it.

Just after we open sourced JMC, I created a temporary mirror on GitHub to experiment with working with JMC at GitHub. That mirror is now closed for business. Please use the official OpenJDK one from now on:

https://github.com/openjdk/jmc

If you forked or stared the old repo, please feel free to fork and/or star the new one!

JFR is Coming to OpenJDK 8!

2019-11-06 - By Marcus

I recently realized that this isn’t common knowledge, so I thought I’d take the opportunity to talk about the JDK Flight Recorder coming to OpenJDK 8! The backport is a collaboration between Red Hat, Alibaba, Azul and Datadog. These are exciting times for production time profiling nerds like me. Smile

The repository for the backport is available here:

http://hg.openjdk.java.net/jdk8u/jdk8u-jfr-incubator/

The proposed CSR is available here:

https://bugs.openjdk.java.net/browse/JDK-8230764

The backport is keeping the same interfaces and pretty much the same implementation as is available in OpenJDK 11, and is fully compatible. There were a few security fixes, due to there not being any module system to rely upon for isolation of the internals, also, some events will not be available (e.g. the Module related events) but other than that the API and tools work exactly the same.

JDK Mission Control will, of course, be updated to work flawlessly with the OpenJDK 8 version of JFR as well. The changes will be minute and are only necessary since Mission Control has some built-in assumptions that no longer hold true.

You can already build and try out OpenJDK 8 with JFR simply by building the JDK available in the repository mentioned above. Also, Aleksey Shipilev provide binaries – see here for details.

Have fun! Smile

Flight Recorder & Mission Control at Code One 2019

2019-08-27 - By Marcus

Code One is rapidly approaching (September 16-19). For fans of JDK Flight Recorder and JDK Mission Control, there will be a lot of relevant activities at Code One. This is an attempt to list them. If I missed something, please let me know!

Sessions

Here are the regular sessions:

Session Name	Presenters	Day	Time	Location
JDK Mission Control: Where We Are, Where We Are Going [DEV4284]	David Buck	Monday	9:00	Moscone South Room 301
Introduction to JDK Mission Control and JDK Flight Recorder [DEV2316]	Marcus Hirt Klara Ward	Monday	16:00	Moscone South Room 202
Improving Observability in Your Application with JFR and JMC [DEV3460]	Marcus Hirt Mario Torre	Tuesday	11:30	Moscone South Room 201
Java Flight Recorder: Black Box of Java Applications[DEV3957]	Poonam Parhar	Wednesday	12:30	Moscone South Room 203
Robotics on JDK 11? With Modules? Are You… [DEV2329]	Marcus Hirt Miro Wengner Robert Savage	Wednesday	16:00	Moscone South Room 313
Four Productive Ways to Use Open Source JFR and JMC Revisited [DEV3118]	Sven Reimers Martin Klähn	Thursday	11:15	Moscone South Room 304
Enhanced Java Flight Recorder at Alibaba [DEV3667]	Sanhong Li Fangxi Yin Guangyu Zhu	Thursday	12:15	Moscone South Room 203
Performance Monitoring with Java Flight Recorder on OpenJDK [DEV2406]	Hirofumi Iwasaki Hiroaki Nakada	Thursday	13:15	Moscone South Room 201

Again, if I’ve missed one, please let me know!

Other Activities

There is going to be a hackergarten session around JMC and JFR, Wednesday at 14:30-16:00, inside of the Groundbreakers booth in the Exhibition Area.
On Friday a few JMC project members are planning to meet up for some coding between 10:00 and 12:00, and then have lunch together at 12:00. Ping me (Marcus) for an invite.
On Wednesday at 18:00 a few JMC project members are planning to go for dinner. Ping me (Marcus) for an invite.

Summary

Lots to do at Code One 2019 for fans of JFR and JMC.
Helpful links above.