Add documentation for native memory tracking (NMT) #9788
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Hi @olyagpl ! Can you please have a look at this when you have time? Thanks! |
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| toc_group: debugging-and-diagnostics | ||
| link_title: Native Memory Tracking | ||
| permalink: /reference-manual/native-image/debugging-and-diagnostics/NMT/ | ||
| redirect_from: /reference-manual/native-image/NMT/ |
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| # Native Memory Tracking (NMT) with Native Image | ||
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| Native Memory Tracking (NMT) is a serviceability feature that records off-heap memory usage of your application. The terminology “off-heap memory” is sometimes used interchangeably with “native memory” or “unmanaged memory.” This essentially means any memory that is not managed by the garbage collector. |
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Please start each sentence in a paragraph from a new line (we are still trying to polish this everywhere).
| ## JFR Events for NMT | ||
| The OpenJDK JFR events `jdk.NativeMemoryUsage` and `jdk.NativeMemoryUsageTotal` are supported in Native Image. | ||
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| There are also two Native Image specific JFR events that you can access: `jdk.NativeMemoryUsagePeak` and `jdk.NativeMemoryUsageTotalPeak`. These Native Image specific events have been created to expose peak usage data otherwise not exposed through the JFR events ported over from the OpenJDK. It should be noted that these new are marked as experimental. You may need to enable experimental events in software like JDK Mission control in order to view them. |
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There are also two Native Image specific JFR events that you can access: jdk.NativeMemoryUsagePeak and jdk.NativeMemoryUsageTotalPeak. These Native Image specific events have been created to expose peak usage data otherwise not exposed through the JFR events ported over from the OpenJDK. These new are marked as experimental. You may need to enable experimental events in software like JDK Mission control in order to view them.
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| There are also two Native Image specific JFR events that you can access: `jdk.NativeMemoryUsagePeak` and `jdk.NativeMemoryUsageTotalPeak`. These Native Image specific events have been created to expose peak usage data otherwise not exposed through the JFR events ported over from the OpenJDK. It should be noted that these new are marked as experimental. You may need to enable experimental events in software like JDK Mission control in order to view them. | ||
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| Below is example of what the new events look like viewed using the `jfr` command line tool: |
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See below the example of what the new events look like when viewed using the jfr command line tool:
| eventThread = "JFR Shutdown Hook" (javaThreadId = 63) | ||
| } | ||
| ``` | ||
| To use these JFR events for NMT, JFR must be included as a feature at build time and started at runtime. |
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To use these JFR events for NMT, JFR must be included as a feature at build time and started at runtime. (Learn more in JDK Flight Recorder (JFR) with Native Image).
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@roberttoyonaga, I left some suggestions. Thank you for your contribution! In the description, you mention it should be added/backported to the GraalVM for JDK 23 docs, is that correct? |
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
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Thank you for the review @olyagpl ! I've applied your suggestions and updated the doc |
Yes, that's right. NMT is also supported in GraalVM for JDK 23 so these docs should be backported to that version too. No content needs to be changed for the backport though. |
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Co-authored-by: Olga Gupalo <olga.gupalo@oracle.com>
Summary
Adding some documentation for NMT. This should be added to GraalVM for JDK 23. Thanks!