AOT Map changes during production run

[Vladimir Kozlov]

Hi María,

Please provide command lines you use in your experiments.

 >         And then I did a production run using the generated cache, which
 >         replaced the `aot.map` with a new one that is much smaller:

We don't support incremental update of AOT cache file. What do you mean 
by "replaced the `aot.map`" ?

Thanks,
Vladimir K

On 10/9/25 12:25 AM, María Arias de Reyna Dominguez wrote:
> Hi Ashutosh,
> 
> Training run:
> $ grep '@@ Class ' aot.map | wc -l
> 10884
> 
> Production run:
> $ grep '@@ Class ' aot.map | wc -l
> 3431
> 
> And the sizes of the map file are different:
> $ du -sh aot.map*
> 331M aot.map
> 391M aot.map.0
> 394M aot.map.1
> 
> The aot.map is the production run. The file aot.map.1 is the training run.
> 
> The aot.map.0 is for app.aot.config (app.aot is how I call my aot cache):
> $ cat aot.map.0 | head
> AOT cache map for app.aot.config
> [header             0x0000000000000000 - 0x00000000000003d8       984 bytes]
> $ grep '@@ Class ' aot.map.0 | wc -l
> 10606
> 
> I'm using a locally build version of Java, that's true:
> $ java --version
> openjdk 26-internal 2026-03-17
> OpenJDK Runtime Environment (build 26-internal-adhoc.delawen.jdk)
> OpenJDK 64-Bit Server VM (build 26-internal-adhoc.delawen.jdk, mixed 
> mode, sharing)
> 
> Build from:
> $ git log | head
> commit 4b4d0cd35a32448e4b056109c502af2765766432
> Author: Johny Jose <johny.jose at oracle.com <mailto:johny.jose at oracle.com>>
> Date:   Tue Oct 7 13:13:42 2025 +0000
> 
>      8365398: TEST_BUG: java/rmi/transport/checkLeaseInfoLeak/ 
> CheckLeaseLeak.java failing intermittently
> 
>      Reviewed-by: msheppar, smarks, jpai
> 
> I'm confused :)
> 
> On Wed, Oct 8, 2025 at 6:31 PM Ashutosh Mehra <asmehra at redhat.com 
> <mailto:asmehra at redhat.com>> wrote:
> 
>     Hi Maria,
>     This is strange. I tried the same using the JavacBench app and
>     didn't see this discrepancy in the map file generated by the
>     assembly phase and the production run.
>     You may have already checked it but just to confirm if run "grep '@@
>     Class ' t.log | wc -l" on the map file, do you see the same difference?
> 
>     Thanks,
>     - Ashutosh Mehra
> 
> 
>     On Wed, Oct 8, 2025 at 4:36 AM María Arias de Reyna Dominguez
>     <mariasde at redhat.com <mailto:mariasde at redhat.com>> wrote:
> 
>         Hi!
> 
>         I have a question.  I did a training run and generated what
>         looks like a valid cache.
> 
>         Summary of the number of elements (for certain types of
>         elements) the map contains:
>         ```
>         Classes in AOT Cache: 10.885
>         Methods in AOT Cache: 121.393
>            -> ConstMethods: 121.293
>            -> MethodCounters: 6.530
>            -> MethodData: 4.127
>         ConstantPool: 10.197
>            -> ConstantPoolCache: 10.197
>         ```
> 
>         And then I did a production run using the generated cache, which
>         replaced the `aot.map` with a new one that is much smaller:
> 
>         ```
>         Classes in AOT Cache: 3.431
>         Methods in AOT Cache: 38.359
>            -> ConstMethods: 38.359
>            -> MethodCounters: 0
>            -> MethodData: 0
>         ConstantPool: 3.067
>            -> ConstantPoolCache: 3.067
>         ```
> 
>         As you can see, there are a lot of missing elements!
> 
>         If I check the md5sum of the actual cache file before and after
>         the production run, it stays the same. It is the AOT Cache Map
>         which changes. Is that... supposed to happen?
> 
>         Maybe it is a bug related to https://bugs.openjdk.org/browse/
>         JDK-8362566 <https://bugs.openjdk.org/browse/JDK-8362566> ?
> 
>         Both map files start with `AOT cache map for app.aot`, it is not
>         the map file for the `app.aot.config` that appears during the
>         training run.
> 
>         Both the training and the run were the same: just spin up an
>         Infinispan server and shut it down after a few seconds. But I
>         guess that's irrelevant because the aot cache file is exactly
>         the same.
> 
>         I could stop generating the aot map file on the production run
>         because there is no need for it, but I forgot to remove it...
>         and then this happened.
> 
>         Kind regards,
>         María Arias de Reyna Domínguez
>         Senior Software Engineer
>         She / Her / Hers
>         ariasdereyna at redhat.com <mailto:ariasdereyna at redhat.com>
>