On Sun, 11 May 2025 04:57:44 GMT, Ioi Lam <ik...@openjdk.org> wrote: > https://openjdk.org/jeps/483 mentions: > >> To enjoy the benefits of the AOT cache generated during a training run, the >> training run and all subsequent runs must be essentially similar. [...] All >> runs must not use JVMTI agents that can arbitrarily rewrite classfiles >> using ClassFileLoadHook. > > However, when *any* java agent is specified in the training run, the JVM > fails at start-up. E.g., > > > $ java -XX:AOTMode=record -javaagent:agent.jar -cp app.jar App > Error occurred during CDS dumping > Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS > dumping > > > With the AOT cache, the main concern for JVMTI agents is that they can modify > the contents of loaded Java classes. If we store such modified classes into > the AOT cache, their contents will no longer match the original class files > (from application JAR files, etc). As a result, when using the AOT cache in > production runs, the application may have unexpected behavior. > > With this PR, we allow JVMTI agents in the AOT workflow. To address the above > concern, we ensure that JVMTI agents cannot affect the contents of AOT cache: > > - In training runs (`java -XX:AOTMode=record`), JVMTI agents are allowed, > but the AOT configuration file should filter out classes that are transformed > by the agents. This can be checking `InstanceKlass::has_been_redefined()` and > `ClassFileStream::from_class_file_load_hook()`. > > - In the assembly phase (`java -XX:AOTMode=record`), agents can be specified > in the command-line. However, since the assembly phase doesn't execute any > application logic, we will also not load any of the specified agents. > Therefore, the agents cannot affect the contents of the AOT cache created in > the assembly phase.
src/hotspot/share/prims/jvmtiAgent.cpp line 588: > 586: // Agents are allowed with -XX:AOTMode=record and > -XX:AOTMode=on/auto. > 587: // Agents are completely disabled when -XX:AOTMode=create > 588: assert(!CDSConfig::is_dumping_final_static_archive(), "agents should > have been disabled with -XX:AOTMode=create"); Is there a point in asserting this? I am thinking users would pass the same command line to `-XX:AOTMode=create` without thinking twice. And since we are doing the right thing, ignoring the agents, it seems we "only" need to print the user-visible warning. Maybe not even that, and just return? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/25170#discussion_r2084856035
