RFR: 8237192: Generate stripped/public pdbs on Windows for jdk images

[Erik Joelsson]

On 2020-01-23 00:03, Baesken, Matthias wrote:
> Hi Erik,  yes true sorry for answering  your comments a bit late .
>
>> If a user runs jlink and includes all the jmods we ship with the JDK, the result
>> should be essentially equivalent to the original JDK image. The way the
>> stripped pdb files are included in the bundles sort of at the last
>> second of the build here breaks this property.
> I think we should address this in a separate bug/CR .
Maybe. I realize that my proposal below is quite a big task. But on the 
other hand, I don't think breaking the relationship between the jmods 
and the distribution bundles is on the table really.
> Looking for example  into a Linux  build, I see  a lot of debuginfo files  in the jdk image (more or less for every shared lib)  .
> But when looking into the jmods  of that jdk image ,  no debuginfo files are in there ( I checked the java.base jmod).
> So  putting  the  files with debug information into the jmods  seems to be something that was not done so far  cross platform  (or is there some build switch  for it that I did not check?) .
> Maybe to keep the jmods as small as possible .

No, we do not put the debuginfo files in the jmods nor the bundles 
because those are not intended to be shipped to customers. We are 
currently overlaying them into images/jdk in the build output to make 
them available for local debugging. (This is convoluted and I would very 
much like to get away from this practice at some point so that there is 
a 1-1 mapping between images/jdk and bundles/jdk*-bin.tar.gz.) The 
stripped pdb files you are proposing are on the contrary intended for 
shipping to customers (as I understand your proposal) so comparing them 
with the debuginfo files is not relevant.

Now if MS had been kind enough to define a separate file type for the 
stripped pdbs, so that they could live alongside the full pdbs, we 
wouldn't have this issue. The heart of the problem is that only one set 
of files (either stripped or full) can be present and usable in 
images/jdk at a time. We have 2 main uses for images/jdk.

1. Developer running and debugging locally

2. Serve as the source for generating the distribution bundles

We currently have one image serving both of these purposes, which is 
already creating complicated and convoluted build steps. To properly 
solve this I would argue for splitting these two apart into two 
different images for the two different purposes. The build procedure 
would then be, first build the images for distribution, only containing 
what should go into each bundle. Then create the developer jdk image by 
copying files from the distribution images. On Windows, the first image 
would contain the stripped pdbs and when building the second, those 
would get overwritten with the full pdbs.

Now that I figured out a working model that would solve a bunch of other 
problems as well, I would love to implement it, but I doubt I will have 
time in the near future.

/Erik

>
>> To properly implement this, care will need to be taken to juggle the two
>> sets of pdb files around, making sure each build and test use case has
>> the correct one in place where and when it's needed. Quite possibly, we
>> cannot cover all use cases with one build configuration. Developers
>> needing the full debug symbols when debugging locally would likely need
>> to disable the stripped symbols so they get the full symbols everywhere.
>> Possibly this would need to be the default for debug builds and
>> configurable for release builds.
>  From my limited experience , the developers  do not work with the bundles (that  would contain now after my patch the stripped pds)  but with a "normal" jdk image that  is created my make all.
>
> Best regards, Matthias
>
>
>
>> This still does not address anything in my objection.
>>
>> /Erik
>>
>> On 2020-01-22 07:46, Baesken, Matthias wrote:
>>> Hello,  here is an updated version  :
>>>
>>> http://cr.openjdk.java.net/~mbaesken/webrevs/8237192.3/
>>>
>>> this one supports a configure switch  "--enable-stripped-pdbs"    to enable
>> the feature .
>>> Best regards, Matthias
>>>
>>>
>>>> -----Original Message-----
>>>> From: Baesken, Matthias
>>>> Sent: Dienstag, 21. Januar 2020 11:03
>>>> To: 'David Holmes' <david.holmes at oracle.com>; 'build-
>>>> dev at openjdk.java.net' <build-dev at openjdk.java.net>; 'hotspot-
>>>> dev at openjdk.java.net' <hotspot-dev at openjdk.java.net>
>>>> Subject: RE: RFR: 8237192: Generate stripped/public pdbs on Windows for
>>>> jdk images
>>>>
>>>>
>>>> Hi David ,  yes I think it makes sense to have a configure option for this .
>>>> Not everyone would like to have a larger JDK (even it is only a bit larger).
>>>>