RFR: 8311302: Allow for jlinking a custom runtime without packaged modules being present [v18]
Magnus Ihse Bursie
ihse at openjdk.org
Fri Mar 8 16:54:59 UTC 2024
On Tue, 27 Feb 2024 15:23:09 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:
>> Please review this patch which adds a jlink mode to the JDK which doesn't need the packaged modules being present. A.k.a run-time image based jlink. Fundamentally this patch adds an option to use `jlink` even though your JDK install might not come with the packaged modules (directory `jmods`). This is particularly useful to further reduce the size of a jlinked runtime. After the removal of the concept of a JRE, a common distribution mechanism is still the full JDK with all modules and packaged modules. However, packaged modules can incur an additional size tax. For example in a container scenario it could be useful to have a base JDK container including all modules, but without also delivering the packaged modules. This comes at a size advantage of `~25%`. Such a base JDK container could then be used to `jlink` application specific runtimes, further reducing the size of the application runtime image (App + JDK runtime; as a single image *or* separate bundles, depending on the app
being modularized).
>>
>> The basic design of this approach is to add a jlink plugin for tracking non-class and non-resource files of a JDK install. I.e. files which aren't present in the jimage (`lib/modules`). This enables producing a `JRTArchive` class which has all the info of what constitutes the final jlinked runtime.
>>
>> Basic usage example:
>>
>> $ diff -u <(./bin/java --list-modules --limit-modules java.se) <(../linux-x86_64-server-release/images/jdk/bin/java --list-modules --limit-modules java.se)
>> $ diff -u <(./bin/java --list-modules --limit-modules jdk.jlink) <(../linux-x86_64-server-release/images/jdk/bin/java --list-modules --limit-modules jdk.jlink)
>> $ ls ../linux-x86_64-server-release/images/jdk/jmods
>> java.base.jmod java.net.http.jmod java.sql.rowset.jmod jdk.crypto.ec.jmod jdk.internal.opt.jmod jdk.jdi.jmod jdk.management.agent.jmod jdk.security.auth.jmod
>> java.compiler.jmod java.prefs.jmod java.transaction.xa.jmod jdk.dynalink.jmod jdk.internal.vm.ci.jmod jdk.jdwp.agent.jmod jdk.management.jfr.jmod jdk.security.jgss.jmod
>> java.datatransfer.jmod java.rmi.jmod java.xml.crypto.jmod jdk.editpad.jmod jdk.internal.vm.compiler.jmod jdk.jfr.jmod jdk.management.jmod jdk.unsupported.desktop.jmod
>> java.desktop.jmod java.scripting.jmod java.xml.jmod jdk.hotspot.agent.jmod jdk.i...
>
> Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:
>
> Only show runtime image suffix for JDK modules
make/Images.gmk line 96:
> 94:
> 95: ifeq ($(JLINK_KEEP_PACKAGED_MODULES), true)
> 96: ifeq ($(JLINK_PRODUCE_RUNTIME_LINK_JDK), true)
I don't get it. Why don't you use the JDK_LINK_OUTPUT_DIR from just above?
make/Images.gmk line 104:
> 102: endif
> 103:
> 104:
Is this extra line intentional?
make/Images.gmk line 144:
> 142: OUTPUT_DIR := $(JDK_IMAGE_DIR), \
> 143: SUPPORT_DIR := $(JDK_RUN_TIME_IMAGE_SUPPORT_DIR), \
> 144: PRE_COMMAND := $(RM) -r $(JDK_IMAGE_DIR), \
This looks scary! Why the rm? Are you sure you are not racing with some other rule that tries to read from the JDK_IMAGE_DIR?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14787#discussion_r1517984170
PR Review Comment: https://git.openjdk.org/jdk/pull/14787#discussion_r1517983052
PR Review Comment: https://git.openjdk.org/jdk/pull/14787#discussion_r1517982726
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