RFR: 8369736 - Add management interface for AOT cache creation [v11]

Wed Dec 3 20:47:48 UTC 2025

On Wed, 26 Nov 2025 20:35:11 GMT, Mat Carter <macarte at openjdk.org> wrote:

>> Add jdk.management.AOTCacheMXBean. The interface provides a single action that when called will cause any hosted JVM currently recording AOT information will stop recording. Existing functionality is preserved: when stopped the JVM will create the required artifacts based on the execution mode. Conveniently as the application running on the JVM has not stopped (as was previously the only way to stop recording), the application will resume execution after the artifacts have been generated.
>> 
>> The interface will return TRUE if a recording was successfully stopped, in all other cases (not recording etc.) will return FALSE
>> 
>> It follows that invoking the action on a JVM that is recording, twice in succession, should (baring internal errors) produce the following two responses:
>> 
>> TRUE
>> FALSE
>> 
>> Passes tier1 on linux (x64) and windows (x64)
>
> Mat Carter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixed spaces and CRLF

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 37:

> 35:  * <p> The management interface is registered with the platform {@link MBeanServer
> 36:  * MBeanServer}. The {@link ObjectName ObjectName} that uniquely identifies the management
> 37:  * interface within the {@code MBeanServer} is: "jdk.management:type=HotSpotAOTCache".

Drop the colon after "is", and put the object name in `{@code ...}` rather than double quotes.

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 44:

> 42:  * {@code HotSpotAOTCacheMXBean} defines one operation at this time to
> 43:  * end the AOT recording. More operations and/or properties may be added in a
> 44:  * future release.

Drop this paragraph. It's obvious that there's only one operation, and uncertain statements about future releases add no value.

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 50:

> 48: public interface HotSpotAOTCacheMXBean extends PlatformManagedObject {
> 49:   /**
> 50:    * If an AOT recording is in progress, ends the recording. This operation completes

s/operation completes/method returns/

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 53:

> 51:    * after the AOT artifacts have been completely written.
> 52:    *
> 53:    * <p>The JVM will start recording AOT artifacts upon start-up if certain JVM options are

s/certain/appropriate/ -- "certain" suggests that you're not going to tell the reader what they are.

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 57:

> 55:    * the {@code endRecording} method is called. Examples:
> 56:    *
> 57:    * <p> java -XX:AOTCacheOutput=app.aot ....

Put this command, and the others below, in `{@code ...}`, and precede them with a dollar prompt (`$`) so that they look more like command lines.

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 63:

> 61:    *    that will be used to generate the AOT cache file app.aot. In a future execution of this application,
> 62:    *    -XX:AOTCache=app.aot can be provided to improve the application's
> 63:    *    start-up and warm-up performance.

Tighten and clarify: `The JVM records optimization information for the current application in the AOT cache file {@code app.aot}. in a future run of the application, the option {@code -XX:AOTCache=app.aot} will cause the JVM to use the cache to improve the application's startup and warmup performance.`

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 69:

> 67:    *
> 68:    * <blockquote>
> 69:    *    The JVM will record optimization information about the current application

`The JVM records optimization information for the current application in the AOT configuration file {@code app.aotconfig}. ...`

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 84:

> 82:    *
> 83:    * <p> There are also no APIs to querying whether the AOT recording is in progress, or what AOT
> 84:    * artifacts are being recorded.

Drop "Note:", it's meaningless. Merge these two paragraphs. s/to querying/to query/. s/the AOT/an AOT/.

src/jdk.management/share/classes/jdk/management/HotSpotAOTCacheMXBean.java line 92:

> 90:    * procedures rely on an external agent to select the correct moment to end training.
> 91:    * In this way the selected length of training produces the correct set of AOT
> 92:    * optimizations in the AOT archive, without interfering with the application code.

You seem to be saying here that using this method from within an application is not necessarily the best approach, but you say it in a very roundabout way. Consider something like:

     * This method enables an application to end its own AOT recording
     * programatically, but that is not necessarily the best approach. Doing so
     * requires changing the application’s code, which might not be
     * feasible. Even when it is feasible, injecting training-specific logic
     * into the application reduces the similarity between training runs and
     * production runs, potentially making the AOT cache less effective. It may
     * be better to arrange for an external agent to end the training run,
     * thereby creating an AOT cache without interfering with the application’s
     * code.
 ```

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PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586483272
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586486393
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586493320
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586488596
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586490840
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586506998
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586509392
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586515533
PR Review Comment: https://git.openjdk.org/jdk/pull/28010#discussion_r2586550031