Review request 6981484: Update development launcher

Fri Sep 24 09:47:23 PDT 2010

.. and I forgot to attach the following maybe usefull links to Joe
Darcy's blogs about the problems and recent reengineering of the
default Java launcher:

What is the launcher? at http://blogs.sun.com/darcy/entry/what_is_the_launcher
Purging LD_LIBRARY_PATH at
http://blogs.sun.com/darcy/entry/purging_ld_library_path

Regards,
Volker

On Thu, Sep 23, 2010 at 5:13 PM, Volker Simonis
<volker.simonis at gmail.com> wrote:
> Hi,
>
> I think the main problem is not that we have two (in fact four)
> launchers, but that they are located in two workspaces.
>
> The main reason why I use 'gamma' is because I usually only build the
> 'hotspot' project and not 'jdk' which contains the standard 'java'
> launcher.
>
> Another reason for using 'gamma' is that it doesn't do a 'execv()'
> system call to run with a new LD_LIBRARY_PATH like this is done by
> 'java' launcher. This  'execv()' usually confuses debuggers. In order
> to avoid it, one has to set the right LD_LIBRARY_PATH (i.e. the one
> that would be build by the launcher anyway) before calling 'java'.
> This all is kind of "how to debug the HotSpot" wizard knowledge spread
> over various blogs and email threads.
>
> I don't really see a problem in the fact that libjvm.so doesn't get
> loaded when the launcher is started. Just do a first run with:
>
> (gdb) run -version
>
> which loads all the necessary dynamic objects. Then it's easily
> possible to set breakpoints wherever you want. (And double checking
> that you debug the right version of libjvm.so is never a fault:)
>
> To cut a long story short:
> - I don't think that its possible to keep two launchers in sync if
> they are in different workspaces ('hotspot' and 'jdk') nor do I think
> that it's possible to factor out some common code between the two
> workspaces.
> - We should have a launcher in Hotspot which is as simple as possible
> and not dependant on the one from 'jdk' anymore. Therefore it doesn't
> really matter where we start from (taking the one from jdk7 would be a
> natural choice though)
> - as much as possible common code of the new HotSpot launcher ('gamma'
> or 'fusion' or whatever..)should be factored out into the shared code
> space (/share/vm/tools/..).
> - the main design goal of the new launcher should be easy
> 'debuggability' (i.e. no execv()) and an easy possibility to chose a
> runtime JDK to run with (from command line or from the environment).
>
> Regards,
> Volker
>
> On Wed, Sep 22, 2010 at 9:46 PM, Coleen Phillimore
> <coleen.phillimore at oracle.com> wrote:
>>
>> Hi,
>>
>> I think we should use the jdk7 version that you have in the windows build
>> for all platforms.  Many/most of the launcher jdk7 changes seem to be
>> introducing the JLI layer and fixing some bugs.    The platform dependent
>> java_md.{ch} can be in os/<os>/launcher, and the java.c (which is the most
>> code) in share/vm/tools/launcher - there isn't really risk to changing the
>> solaris and linux versions since most people don't use them except for
>> debugging.  The only change that people would notice is if the libjvm.so is
>> no longer statically linked in, because this is the primary benefit:
>>
>> dbx gamma
>> stop in <some vm function>  # no complaints from the debugger because
>> libjvm.so is loaded already
>> run
>> <stop at break>    # except this doesn't seem to work on linux now anyway
>>
>> I can forsee using the launcher for development testing so having the latest
>> jdk7 version makes a lot of sense, and having them consistent by platforms
>> would be good going forward.   I hope this isn't a ton of work to do though.
>>
>> thanks,
>> Coleen
>>
>> On 09/22/10 14:59, Staffan Larsen wrote:
>>
>> Thanks for the review, Coleen.
>>
>> Yes, the files are almost identical and we should really have just one set.
>> There were two main reasons why I duplicated the code, and neither of them
>> is very good:
>>
>> 1) The code in /os/(linux|solaris)/launcher/* is based on the launcher in
>> 1.6.0-b28 (at least the comment in java.c says so). I couldn't easily find
>> that source code to grab the windows files from, so I got them from some
>> other build (6.0u22-b01). There was enough difference between these to make
>> the platform independent and platform dependent files incompatible.
>> 2) I didn't want to make more changes than I had to, so I didn't want to
>> touch the linux or solaris launchers.
>>
>> Perhaps there is even a third reason: There was already a precedent of
>> having the linux and solaris code duplicated, so I just did the same thing
>> for windows. Seems we would really benefit from a "posix" branch with common
>> linux and solaris code in - in fact, the platform dependent parts of the
>> launcher are the same for linux and solaris.
>>
>> In retrospect, none of these reasons are good enough, and we should use the
>> same code as much as possible. Any thoughts on what version on the launcher
>> I should use as baseline? The latest one from jdk7? A stable one from jdk6?
>>
>> Thanks,
>> /Staffan
>>
>>
>> On 22 sep 2010, at 16.20, Coleen Phillimore wrote:
>>
>>
>>
>> Hi Staffan,
>> Is this file src/os/windows/launcher/java.c
>> the same as ./os/linux/launcher/java.c and ./os/solaris/launcher/java.c
>> In fact, the sources in os/linux/launcher are almost exactly the same as
>> os/solaris/launcher.
>> Can we have just one set?  Perhaps put it in directory
>> src/share/tools/launcher and make the makefiles use these sources instead?
>> Sorry to make more work but having the same 2000 lines of code somewhere
>> else, guarantees one copy will always be wrong.
>>
>> Thanks,
>> Coleen
>>
>> On 09/22/10 08:38, Staffan Larsen wrote:
>>
>>
>> Here we go again: http://cr.openjdk.java.net/~sla/6981484/webrev.03/
>>
>>
>> Eventually, I'll get there...
>>
>> Thanks,
>> /Staffan
>>
>> -----Original Message-----
>> From: Christian Thalinger
>> Sent: den 22 september 2010 2:38
>> To: Staffan Larsen
>> Cc:
>> hotspot-dev at openjdk.java.net
>>
>> Subject: RE: Review request 6981484: Update development launcher
>>
>> On Wed, 2010-09-22 at 05:23 -0700, Staffan Larsen wrote:
>>
>>
>>
>>
>> Thanks Christian - I obviously have some things to learn as a new
>> committer - didn't think about the copyrights :-)
>>
>>
>>
>>
>> Sure.  I was going the same route :-)
>>
>>
>>
>>
>>
>> http://cr.openjdk.java.net/~sla/6981484/webrev.02/
>>
>>
>> Now with updated copyrights.
>>
>>
>>
>>
>> As David already said.
>>
>> -- Christian
>>
>>
>>
>>
>>
>>
>>
>