RFR: 8328313: Archived module graph should allow identical --module-path to be specified during dump time and run time [v9]

[David Holmes]

On Tue, 1 Oct 2024 17:30:10 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

>> Prior to this patch, if `--module-path` is specified in the command line:
>> during CDS dump time, full module graph will not be included in the CDS archive;
>> during run time, full module graph will not be used.
>> 
>> With this patch, the full module graph will be included in the CDS archive with the `--module-path` option. During run time, if the same `--module-path` option is specified, the archived module graph will be used.
>> 
>> The checking of module paths between dump time and run time is more lenient compared with the checking of class paths; the ordering of the modules is unimportant, duplicate module names are ignored.
>> E.g. the following is considered a match:
>> dump time      runtime
>> m1,m2             m2,m1
>> m1,m2             m1,m2,m2
>> 
>> I included some [notes](https://bugs.openjdk.org/browse/JDK-8328313?focusedId=14699275&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14699275) in the bug report regarding some changes in the corelib classes.
>
> Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:
> 
>   trailing whitespace

Nothing further from me on the VM side. Just a couple of minor nits.

Thanks

src/hotspot/share/cds/filemap.cpp line 974:

> 972:   if (header()->has_full_module_graph() && !matched_module_paths) {
> 973:     CDSConfig::stop_using_optimized_module_handling();
> 974:     log_info(cds)("optimized module handling: disabled because mismatched module paths");

Suggestion:

    log_info(cds)("optimized module handling: disabled because of mismatched module paths");

src/hotspot/share/cds/heapShared.cpp line 885:

> 883:       ClassLoaderExt::num_module_paths() > 0) {
> 884:     // ArchivedModuleGraph was created with a --module-path that's different than the runtime --module-path.
> 885:     // Thus, it might contain references to modules that do not exist in runtime. We cannot use it.

Suggestion:

    // Thus, it might contain references to modules that do not exist at runtime. We cannot use it.

src/hotspot/share/classfile/classLoaderExt.cpp line 123:

> 121: 
> 122:   // Sort the module paths before storing into CDS archive for simpler
> 123:   // checking during runtime.

Suggestion:

  // checking at runtime.

-------------

Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21048#pullrequestreview-2341785448
PR Review Comment: https://git.openjdk.org/jdk/pull/21048#discussion_r1783757502
PR Review Comment: https://git.openjdk.org/jdk/pull/21048#discussion_r1783754320
PR Review Comment: https://git.openjdk.org/jdk/pull/21048#discussion_r1783758610