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From Pavel Pervov <pmcfi...@gmail.com>
Subject Re: Hello Pavel, inquiring about Harmony bug 5505
Date Wed, 18 Feb 2009 21:23:30 GMT

I still strongly recommend writing to Apache Harmony developers list -
you'd get wider audience and better support. This is the most correct
way of asking questions in the Open Source communities too. I'm the
one of the Harmony community but I'm not the only one.

Getting back to the problem you are trying to solve.

Every implementation may have resource leaks. The only way you can try
to make sure you have "no leaks" is executing java as a separate
process - this way you make OS responsible for freeing most of
resources associated with the process. You can write standalone java
program which asks your radar to generates images as many times per a
time intreval as you may need and have it communicate by the means of
IPC with your C++ code. Then you can command your java program to
restart as soon as you detect any problem you decide is critical
for stability (in your example, some network problems) or after some
time interval elapses. This will bring you to ~100% reliability of
your system.

Well, the patch was never finished, but if you dare to complete it
yourself - the revision it was made against is 638258 as it can be
seen from the patch itself.

Hope to see you on the list.


On Wed, Feb 18, 2009 at 10:11 PM,  <webmaster@quadmore.com> wrote:
> Hello,
> The radar is pretty heavy-duty, it will generate an image in Java every 3
> seconds.
> We want to have a means of cleaning up after network problems, or because
> of memory leaks, without stopping the C++ executable.
> There are probably other ways of doing this but the prototypes have been
> very simple so far (C++ calls a java.awt.graphics program, which generates
> image, transfers image thru a binary stream to C++ which displays it in an
> MFC window).
> I haven't looked at the alternatives to work around the bug, which is in
> every Sun implementation tried.
> Do you have an SVN tag of SDK code I could download and apply the patch to
> if I get desperate ?
> Best regards,
> B
>> Bert,
>> It is much more useful to write to Harmony dev-list, as you can
>> attract more attention to your requests or problems.
>> Unfortunately, I had no chance of working on HARMONY-5505 once I've
>> submitted the work-in-progress patch for it.
>> Are you planning to use radar only occasionally - say once per several
>> hours - so that shutting down and starting up new VM each time becomes
>> an advantage? Is it possible to create the virtual machine and have it
>> suspended in the background until you need to call to radar interface
>> functions? The VM can be configured through command-line to not
>> consume much of resources so it can live with your main application
>> without conflicts.
>> Wating for your ideas.
>> Pavel.
>> On Wed, Feb 18, 2009 at 6:59 PM,  <webmaster@quadmore.com> wrote:
>>> Hello,
>>> I am inquiring about the issue "[drlvm][JNI] Unable to create, destroy,
>>> create VM in the same process."
>>> mentioned in :
>>> http://issues.apache.org/jira/browse/HARMONY-5505
>>> We have a new type of radar with a closed-box Java interface to connect
>>> to
>>> a C++ maritime traffic control system. I have made a few JNI prototypes
>>> which seem very promising, but it will run 7/24 and it would be very
>>> advantageous to create, destroy, create VM in the same JNI Invocation
>>> process.
>>> What is the status of this bug, is the patch to be included in a future
>>> version?
>>> Best regards,
>>> Bert Szoghy
>>> INNAV System
>>> xst.ca

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