RFR [9] Modular Source Code

[Erik Joelsson]

I should probably write something about the rather extensive changes to 
the build logic in this patch.

As the source gets organized around modules, it made sense to also 
organize the build more around modules. In this patch, the makefiles 
have in large parts been split into module specific files and the top 
level targets are oriented around modules. This means the top level 
targets are much more fine granular than currently in JDK 9.

Another difference is that the top level targets are now able to run 
concurrently, to give more opportunity for utilizing multiple cpus. In 
JDK 9, the build moves sequentially through each repository, in a given 
order, now make is free to run more things in parallel. This makes the 
build faster, at least on beefy hardware. The drawback is that the build 
log gets a bit more confusing. When something fails, it won't interrupt 
other building threads at once, so the actual failure may be further up 
the log (even further than before). I have found that searching for 
"Error 2" is a good way to find the real failure. Another consequence is 
that the build time summary at the end only displays total time as there 
is no good definition for how much time was spent in each repository 
anymore.

A summary on the new targets:

make [default]
Does pretty much the same as before. It compiles everything but does not 
build all jars or create images.

make all
Builds everything, including jars, images and docs. Also runs a 
verification tool on the java classes which will point out any broken 
module boundaries.

make images
Same as before

make hotspot
Builds the hotspot repository, like before.

make docs
Builds all the documentation, including javadoc.

make docs-javadoc
Builds just the javadoc. This target has very few prerequisites so 
provides a fast way to just build javadoc.

make gensrc
Runs all source code generation steps.

make java
Compiles all java classes.
Other similar targets are libs, launchers, gendata and copy

make java.desktop
Compiles everything in the java.desktop module (and its dependencies), 
both java and native code. Works for any module name.

make java.desktop-java
Compiles the java classes in java.desktop (and its dependencies). Works 
for any module name (and -gensrc, -libs, -launchers, -gendata, -copy)

In addition to this, the suffix -only can be added to any target to 
disable the prerequisites for it. Using this is not recommended but it 
may save time when doing certain incremental builds and you are in a 
terrible hurry.

For incremental builds, sjavac can be used and works reasonably well 
(configure --enable-sjavac). Work is in progress on making it work even 
better. The old workaround JDK_FILTER=package/to/compile is still working.

The clean target is still oriented around repositories, mostly because 
the build output is still in large parts repository oriented. This is 
something we hope to improve later.

/Erik


On 2014-08-12 16:10, Chris Hegarty wrote:
> This is a review request for the Initial changes for JEP 201: Modular Source Code [1].
>
> There are a number of individuals responsible for these changes. Some, possibly not all, are explicitly listed in the To section of this mail, and they will help address any comments arising from this review request.
>
> For the purposes of review, the actual source file moves have been omitted from the webrev below, with the exception of any source file that has a change to it’s actual content. The new location of the source files can be determined from JEP 201 [1] and JEP 200 "The Modular JDK" [2], or by browsing the staging forest [3].
>
> Webrevs:
>   http://cr.openjdk.java.net/~chegar/8054834/00/
>
> Due to the significant impact of these changes, a JDK 9 promotion has been tentatively reserved for their integration. All comments are welcome, although given the nature of the changes then we might have to create separate issues in JIRA to address some of them later in jdk9/dev..
>
> -Chris.
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8051619
> [2] https://bugs.openjdk.java.net/browse/JDK-8051618
> [3] http://hg.openjdk.java.net/jigsaw/stage