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Questions tagged [jfr]

JRockit/Java/JDK Flight Recorder (JFR), a performance monitoring and profiling tool

176 questions
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How to use HeapDump and JFR properly?

I'm running a Java application using a container, but I'm trying to output a HeapDump when an OutOfMemoryError occurs. However, there is also an opinion that it is better to use JFR. Please tell me how to use these. Also, I'm worried that the size…
YutaSaito
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JDK Mission Control app is not launching in Mac system

I have installed jmc-8.2.1_osx-aarch64 in my mac OS. Java version used is 11.0.14. I have also installed eclipse in my machine. When I am trying to launch the JDK Mission Control app, its erroring out as , "The JVM shared library…
Eli Johnes
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Java Flight Recorder - Async I/O support

Does JFR support Async I/O? I am using Java Flight Recorder (on HotSpot 1.8.0_144) + Mission Control to profile an app. On the File IO tabs of Mission Control, I see orders of magnitude less "activity" than I expected and that I know to be actually…
cmhteixeira
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Does OpenJDK 11 support Java Flight Recorder?

Following this post : jfr is supported natively in openjdk 11 and it is confirmed by the features list of OpenJDK 11: 328: Flight Recorder However, from this DZone article, about using JFR-linked option -XX:+UnlockCommercialFeatures: OpenJDK…
ThCollignon
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Java Flight Recorder is not reporting any File I/O events

One of the advertised features of Java Flight Recorder is the ability to report the file created, read or force in the File I/O tab in JMC 8.1 To test this feature, I created a small application that uses Apache commons-io to copy a large file from…
Samrat
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Is there a C#/.NET equivalent for the JVM's JMC+JFR for continuous profiling in production?

Java Flight Recorder (JFR) coupled with JDK Mission Control provides an excellent platform for continuous/always-on profiling in production. Is there an analogous offering for C#/.NET (Core)? I read about EventCounters but those only seem to be a…
Ziad
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Deobfuscating stacktraces and class/method names in JDK Flight Recorder files

We would like to use the JDK Flight Recorder to let our end users send us profiling data that we could analyze internally using JDK Mission Control. The only problem is that our code is obfuscated which makes stacktraces and events unreadable in i.e…
Billybong
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Is there a way to find total TLABs allocated in JMC 7.x, like there was in JMC 5.x?

In Java Mission Control 5.x, you could easily view the total size of allocated TLABs. See the "Allocation Summary" in the bottom right of this image. In Java Mission Control 7.x, I can't find an easy way to find this high-level information. I can…
beachwood23
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How to read JFR file?

I am a java application with JFR enable, which generated the attached file I am new to using JFR can so I need help reading the file. I need help reading the file. When did the application start and stopped, how much memory was used, what are the…
Neha
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if I have multiple Java flight recorder files (.JFR) , how do I merge them together to see them at Java mission control in one time

I received for analysis a bunch of multiple JFR files , like 170 , and it is taking too long to open one by one, can I put them in one single file, starting from the fact that I only have the files and I cannot configure the JVM and obtain the JFR…
Leo
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Why does the HotSpot ExecutionSample event always return STATE_RUNNABLE?

I'm using the ExecutionSample event from HotSpot in OpenJDK11. It has a field for thread state, but I only ever see one value for the field: STATE_RUNNABLE How does HotSpot choose which threads to sample? Why are they always runnable? Simple…
Curious Java Guy
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How does JFR manage to record stack trace, given it's promises of low-overhead?

Going through https://www.oracle.com/technetwork/java/javaseproducts/mission-control/java-mission-control-wp-2008279.pdf, I ran into the following quote: Most technologies used today to monitor, manage, and profile the Java runtime use fairly…
Elvir Crncevic
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What is GenCollectForAllocation means?

While reading a JFR dump, I came up with a VM Operation called GenCollectForAllocation that is taking more time than other processes. Can anyone explain to me what this operation is?
Eranga Heshan
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How to scrub a Java flight recording

I have a Java flight recording that I want to share. Unfortunately the Java flight recording contains usernames and passwords in system properties and environment variables (JMC correctly warns of this). Is there a way to remove all system…
Philippe Marschall
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Is there a way to start JFR monitoring/recording from remote via code?

I am using Jmeter to do load test using Ant plugin. Currently capturing server's JVM metrics during the test using JFR GUI mode, for each node. It is cumbersome to start for each node and sometimes its getting missed to start. Is there a way to…
aruma
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