small changes, long build time

David Holmes david.holmes at
Sun May 1 04:21:34 UTC 2016

On 30/04/2016 5:53 PM, Alan Bateman wrote:
> On 30/04/2016 08:32, David Holmes wrote:
>> Just to add my concerns here, I was changing the launcher and building
>> images and that caused the jmods to be rebuilt as well. I would not
>> expect that so do we have missing dependency information in the build?
> By "changing the launcher" then do you mean the native code, say in
> jdk/src/java.base/share/native/? There are many modules with native
> launchers and the launcher code is compiled for each one. If you instead
> mean LauncherHelper or other java code then it's in java.base and so the
> classes in that module need to be recompiled and of course everything
> depends on java.base.

The native code - java.c. Can't see any reason for jmods to be recreated 
every time I recompile that!

> As regards the jmod files then they are the packaged modules. The linker
> consumes these so they need to be built before we create the images.
> Also the packaged modules are copied into the `jdk` image (by jlink) as
> it is needed to create custom images.

Sure. But they shouldn't need to be recreated unless something relating 
to their content has changed.


> Anyway points to mention:
> 1. The jmod files are currently huge. This is mostly because of debug
> info. Erik fixed this recently in jdk9/dev via JDK-8155632 but it may
> not have got to all forests yet.
> 2. We have changes coming (should be in jdk9/dev by mid next week) that
> avoids the need to generate the packaged modules in reverse topology
> order. This is the change to the where the integrity hashes are recorded
> that I mentioned in the first reply. This may help with the build times
> a bit although generating the packaged modules is I/O bound so mileage
> may vary.
> -Alan

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