Maximum Java Heap Size/OpenVMS Java Experiences? - VMS

This is a discussion on Maximum Java Heap Size/OpenVMS Java Experiences? - VMS ; Hi, I was wondering if anyone knows what the maximum heap size is that can be specified for OpenVMS Java 5 on Itanium/Alpha? I could only find reference to a '32-bit' option, which I'm presuming isn't the default. Is there ...

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Thread: Maximum Java Heap Size/OpenVMS Java Experiences?

  1. Maximum Java Heap Size/OpenVMS Java Experiences?

    Hi,

    I was wondering if anyone knows what the maximum heap size is that can
    be specified for OpenVMS Java 5 on Itanium/Alpha? I could only find
    reference to a '32-bit' option, which I'm presuming isn't the default.

    Is there any developers out there using Java on VMS? If so, could they
    please share their experience with me. I am a developer since Java 1.1
    and would welcome your opinions on how developing/deploying on OpenVMS
    differs to other environments.

    Many thanks for the help,

    Mark.


  2. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    urbancamo wrote:
    > I was wondering if anyone knows what the maximum heap size is that can
    > be specified for OpenVMS Java 5 on Itanium/Alpha? I could only find
    > reference to a '32-bit' option, which I'm presuming isn't the default.
    >
    > Is there any developers out there using Java on VMS? If so, could they
    > please share their experience with me. I am a developer since Java 1.1
    > and would welcome your opinions on how developing/deploying on OpenVMS
    > differs to other environments.


    I didn't (yet) do too much with Java on VMS, but I think the JDK User's Guide[1]
    has some useful tips, e.g. "Note that you are better off with a smaller heap
    that results in more garbage collections than allowing your application to page
    fault too often due to a large heap size.".

    There's also a paper on Optimizing Java Performance on OpenVMS[2] that - although
    it's not quite current - has some tips.

    HTH,
    Martin

    [1] http://h18012.www1.hp.com/java/docum...ser_guide.html
    [2] http://h71000.www7.hp.com/ebusiness/...gSDKGuide.html
    --
    One OS to rule them all | Martin Vorlaender | OpenVMS rules!
    One OS to find them | work: mv@pdv-systeme.de
    One OS to bring them all | http://www.pdv-systeme.de/users/martinv/
    And in the Darkness bind them.| home: martin.vorlaender@t-online.de

  3. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    Guy Peleg reports that:

    The Java heap size limit is hard coded to 1500MB on OpenVMS. Java
    engineering plan to remove this restriction with a future release.

    I have been working with several customers whose entire application
    is
    Java based. The key for Java performance on OpenVMS is to be running
    Java 5 on OpenVMS V8.3 using Itanium based servers.


  4. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    > Guy Peleg reports that:
    >
    > The Java heap size limit is hard coded to 1500MB on OpenVMS. Java
    > engineering plan to remove this restriction with a future release.


    I'm developing a Multi Agent Simulation where each agent runs as a
    separate thread. Large numbers of threads consume large amounts of
    memory. Hence the question.

    On Windows 32 bit the maximum amount of memory that can be allocated
    is approximately 1.6 GB. On Linux 32 bit I've heard of more, but it is
    the same order of magnitude.

    For my simulation I would estimate that I would need of the order of
    8-16GB of memory.

    Mark.


  5. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    Out of sheer curiosity and thinking it would be easy, I tried to find
    in the on-line documentation what the current maximum WSMAX value is,
    since it looks like that's the next limit.

    Going to the OpenVMS online docs and entering WSMAX in the convenient
    search box, I got one hit the System Management Utilities Reference
    Manual of September 2003 that talked about Authorize and the limits on
    WSQUOTA ... so it wasn't that easy.

    Moving on to Google, I got an early, promising hit on a 2002
    presentation of Christian Moser's though an Oracle website,
    http://www.oracle.com/technology/pro...02_itanium.pdf
    that boasted a "18GB WSMAX." Well, that's closer to an answer, but
    not really documentation. The Google hits wandered through various
    other vendors that might have been useful, but where is an
    authoritative answer?

    Figuring I might know a little more after 20 years of using VMS, I
    looked in the System Manager's Manual v2 for WSMAX and found one
    mention in the section on "Managing the Vector Processing Environment
    (VAX Only) ". Well ...

    System Management Utilities Reference Manual under System Parameters?
    No. SPD? No. After about 15 minutes, I stopped. Experience wan't
    helping either.

    Now, I'm sure someone here knows off hand what the limit to WSMAX is,
    and if I keep looking I'm sure I can find it. But the point of this
    exercise is to try coming from a point of ignorance, and besides
    asking here, how would some find current SYSGEN parameter limits? Or
    as a larger qustion, if someone like the parent author wasn't really
    into VMS, but was trying to find out what some of it's maximum
    configuration limits are, because they might have or want to buy some
    Big Iron, where should they be looking?

    OK, now I have to go do some real work...


    Sean

    On Aug 1, 1:45 am, urbancamo wrote:
    > Guy Peleg reports that:
    >
    > The Java heap size limit is hard coded to 1500MB on OpenVMS. Java
    > engineering plan to remove this restriction with a future release.
    >
    > I have been working with several customers whose entire application
    > is
    > Java based. The key for Java performance on OpenVMS is to be running
    > Java 5 on OpenVMS V8.3 using Itanium based servers.




  6. Re: Maximum Java Heap Size/OpenVMS Java Experiences?


    "urbancamo" wrote in message
    news:1185890971.291076.285690@d55g2000hsg.googlegr oups.com...
    > Hi,
    >
    > I was wondering if anyone knows what the maximum heap size is that can
    > be specified for OpenVMS Java 5 on Itanium/Alpha? I could only find
    > reference to a '32-bit' option, which I'm presuming isn't the default.


    On Itanium, you can't go above 1500MB, it's hard coded limitation that
    (hopefully) will be removed in a future release.

    >
    > Is there any developers out there using Java on VMS? If so, could they
    > please share their experience with me. I am a developer since Java 1.1


    Yes there are....I've worked with several customers that their entire
    application is based on Java. The key for performance is Java 5 on Itanium,
    OpenVMS V8.3 and proper tuning.

    Guy Peleg
    BRUDEN-OSSG
    http://www.brudenossg.com

    > and would welcome your opinions on how developing/deploying on OpenVMS
    > differs to other environments.
    >
    > Many thanks for the help,
    >
    > Mark.
    >




    --
    Posted via a free Usenet account from http://www.teranews.com


  7. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    In article <1185990365.187329.66340@i38g2000prf.googlegroups.c om>,
    sean@obanion.us wrote:

    > Out of sheer curiosity and thinking it would be easy, I tried to find
    > in the on-line documentation what the current maximum WSMAX value is,
    > since it looks like that's the next limit.


    If you do:

    $ MCR SYSGEN SHOW WSMAX

    you get something like this (taken on V8.3, Alpha)


    Parameter Name Current Default Min. Max. Unit Dynamic
    -------------- ------- ------- ------- ------- ---- -------
    WSMAX 393216 8192 1024 134217728 Pagelets
    internal value 24576 512 64 8388608 Pages

    $ write sys$output 134217728/2048 ! max in megabytes
    65536

    i.e. 64 GB, for Alpha running V8.3. You should repeat this on Itanium
    to check that SYSGEN uses the same maximum value there.

    Or did I miss something in your question?

    --
    Paul Sture

    Sue's OpenVMS bookmarks:
    http://eisner.encompasserve.org/~stu...bookmarks.html

  8. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    > On Itanium, you can't go above 1500MB, it's hard coded limitation that
    > (hopefully) will be removed in a future release.


    That's a really horrible, arbitrary limit given the amount of memory
    you can put in an Itanium box. Unfortunately, it wasn't the answer I
    was looking for. I was hoping for a bit more headroom!

    Thanks for the answers - googling has revealed very little about most
    architectures. I am assuming that Sun have ensured that their Solaris
    servers don't suffer from such limits!

    Regards, Mark.


  9. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    What I missed in my quest was to look in front of me. Well, not
    quite, since the Alphas I have access to are runinng 7.3-2.

    But I guess the point I was tring to make was unless I have an the
    system in question (Alpha, Integrity, 7.3, 8.3...) in front of me, how
    would I find this out?

    It's true I have yet to check the FAQs...


    Sean

    On Aug 1, 11:20 am, "P. Sture" wrote:
    > In article <1185990365.187329.66...@i38g2000prf.googlegroups.c om>,
    >
    > s...@obanion.us wrote:
    > > Out of sheer curiosity and thinking it would be easy, I tried to find
    > > in the on-line documentation what the current maximum WSMAX value is,
    > > since it looks like that's the next limit.

    >
    > If you do:
    >
    > $ MCR SYSGEN SHOW WSMAX
    >
    > you get something like this (taken on V8.3, Alpha)
    >
    > Parameter Name Current Default Min. Max. Unit Dynamic
    > -------------- ------- ------- ------- ------- ---- -------
    > WSMAX 393216 8192 1024 134217728 Pagelets
    > internal value 24576 512 64 8388608 Pages
    >
    > $ write sys$output 134217728/2048 ! max in megabytes
    > 65536
    >
    > i.e. 64 GB, for Alpha running V8.3. You should repeat this on Itanium
    > to check that SYSGEN uses the same maximum value there.
    >
    > Or did I miss something in your question?
    >
    > --
    > Paul Sture
    >
    > Sue's OpenVMS bookmarks:http://eisner.encompasserve.org/~stu...bookmarks.html




  10. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    P. Sture wrote:
    > In article <1185990365.187329.66340@i38g2000prf.googlegroups.c om>,
    > sean@obanion.us wrote:
    >
    >
    >>Out of sheer curiosity and thinking it would be easy, I tried to find
    >>in the on-line documentation what the current maximum WSMAX value is,
    >>since it looks like that's the next limit.

    >
    >
    > If you do:
    >
    > $ MCR SYSGEN SHOW WSMAX
    >
    > you get something like this (taken on V8.3, Alpha)
    >
    >
    > Parameter Name Current Default Min. Max. Unit Dynamic
    > -------------- ------- ------- ------- ------- ---- -------
    > WSMAX 393216 8192 1024 134217728 Pagelets
    > internal value 24576 512 64 8388608 Pages
    >
    > $ write sys$output 134217728/2048 ! max in megabytes
    > 65536
    >
    > i.e. 64 GB, for Alpha running V8.3. You should repeat this on Itanium
    > to check that SYSGEN uses the same maximum value there.
    >


    On I64 V8.3:

    $ mcr sysgen show wsmax
    Parameter Name Current Default Min. Max. Unit Dynamic
    -------------- ------- ------- ------- ------- ---- -------
    WSMAX 1089536 131072 16384 134217728 Pagelets
    internal value 68096 8192 1024 8388608 Pages

    Same maximum, but much higher default and min values. "Current" value came
    from AUTOGEN with feedback, AFAIK.

    > Or did I miss something in your question?
    >



    --
    John Santos
    Evans Griffiths & Hart, Inc.
    781-861-0670 ext 539

  11. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    In article , John Santos
    wrote:

    > P. Sture wrote:
    > > In article <1185990365.187329.66340@i38g2000prf.googlegroups.c om>,
    > > sean@obanion.us wrote:
    > >
    > >
    > >>Out of sheer curiosity and thinking it would be easy, I tried to find
    > >>in the on-line documentation what the current maximum WSMAX value is,
    > >>since it looks like that's the next limit.

    > >
    > >
    > > If you do:
    > >
    > > $ MCR SYSGEN SHOW WSMAX
    > >
    > > you get something like this (taken on V8.3, Alpha)
    > >
    > >
    > > Parameter Name Current Default Min. Max. Unit Dynamic
    > > -------------- ------- ------- ------- ------- ---- -------
    > > WSMAX 393216 8192 1024 134217728 Pagelets
    > > internal value 24576 512 64 8388608 Pages
    > >
    > > $ write sys$output 134217728/2048 ! max in megabytes
    > > 65536
    > >
    > > i.e. 64 GB, for Alpha running V8.3. You should repeat this on Itanium
    > > to check that SYSGEN uses the same maximum value there.
    > >

    >
    > On I64 V8.3:
    >
    > $ mcr sysgen show wsmax
    > Parameter Name Current Default Min. Max. Unit
    > Dynamic
    > -------------- ------- ------- ------- ------- ----
    > -------
    > WSMAX 1089536 131072 16384 134217728 Pagelets
    > internal value 68096 8192 1024 8388608 Pages
    >
    > Same maximum, but much higher default and min values. "Current" value came
    > from AUTOGEN with feedback, AFAIK.
    >


    Thanks for that. Ditto here for the "Current" vaalue. Surprisingly, I
    don't see anything (on Alpha) about WSMAX in
    SYS$SYSTEM:AGEN$PARAMS.REPORT, though AUTOGEN is obviously calculating
    it.

    --
    Paul Sture

    Sue's OpenVMS bookmarks:
    http://eisner.encompasserve.org/~stu...bookmarks.html

  12. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    P. Sture wrote:
    > In article , John Santos
    > wrote:
    >
    >
    >>P. Sture wrote:
    >>
    >>>In article <1185990365.187329.66340@i38g2000prf.googlegroups.c om>,
    >>> sean@obanion.us wrote:
    >>>
    >>>
    >>>
    >>>>Out of sheer curiosity and thinking it would be easy, I tried to find
    >>>>in the on-line documentation what the current maximum WSMAX value is,
    >>>>since it looks like that's the next limit.
    >>>
    >>>
    >>>If you do:
    >>>
    >>>$ MCR SYSGEN SHOW WSMAX
    >>>
    >>>you get something like this (taken on V8.3, Alpha)
    >>>
    >>>
    >>>Parameter Name Current Default Min. Max. Unit Dynamic
    >>>-------------- ------- ------- ------- ------- ---- -------
    >>>WSMAX 393216 8192 1024 134217728 Pagelets
    >>> internal value 24576 512 64 8388608 Pages
    >>>
    >>>$ write sys$output 134217728/2048 ! max in megabytes
    >>>65536
    >>>
    >>>i.e. 64 GB, for Alpha running V8.3. You should repeat this on Itanium
    >>>to check that SYSGEN uses the same maximum value there.
    >>>

    >>
    >>On I64 V8.3:
    >>
    >>$ mcr sysgen show wsmax
    >>Parameter Name Current Default Min. Max. Unit
    >>Dynamic
    >>-------------- ------- ------- ------- ------- ----
    >>-------
    >>WSMAX 1089536 131072 16384 134217728 Pagelets
    >> internal value 68096 8192 1024 8388608 Pages
    >>
    >>Same maximum, but much higher default and min values. "Current" value came
    >>from AUTOGEN with feedback, AFAIK.
    >>

    >
    >
    > Thanks for that. Ditto here for the "Current" vaalue. Surprisingly, I
    > don't see anything (on Alpha) about WSMAX in
    > SYS$SYSTEM:AGEN$PARAMS.REPORT, though AUTOGEN is obviously calculating
    > it.
    >


    The same on Itanium. I didn't set it explicitly, and there's nothing
    in MODPARAMS.DAT or in AGEN$PARAMS.REPORT. My rx2620 came from the
    porting workshop, and was pre-loaded with V8.2-1 (since upgraded to V8.3).
    Maybe HP set it, or maybe AUTOGEN set it on the initial install and
    the report is long gone.

    --
    John Santos
    Evans Griffiths & Hart, Inc.
    781-861-0670 ext 539

  13. Re: Maximum Java Heap Size/OpenVMS Java Experiences?

    In article , John Santos
    wrote:

    > P. Sture wrote:
    > > In article , John Santos
    > > wrote:
    > >
    > >
    > >>P. Sture wrote:
    > >>
    > >>>In article <1185990365.187329.66340@i38g2000prf.googlegroups.c om>,
    > >>> sean@obanion.us wrote:
    > >>>
    > >>>
    > >>>
    > >>>>Out of sheer curiosity and thinking it would be easy, I tried to find
    > >>>>in the on-line documentation what the current maximum WSMAX value is,
    > >>>>since it looks like that's the next limit.
    > >>>
    > >>>
    > >>>If you do:
    > >>>
    > >>>$ MCR SYSGEN SHOW WSMAX
    > >>>
    > >>>you get something like this (taken on V8.3, Alpha)
    > >>>
    > >>>
    > >>>Parameter Name Current Default Min. Max. Unit Dynamic
    > >>>-------------- ------- ------- ------- ------- ---- -------
    > >>>WSMAX 393216 8192 1024 134217728 Pagelets
    > >>> internal value 24576 512 64 8388608 Pages
    > >>>
    > >>>$ write sys$output 134217728/2048 ! max in megabytes
    > >>>65536
    > >>>
    > >>>i.e. 64 GB, for Alpha running V8.3. You should repeat this on Itanium
    > >>>to check that SYSGEN uses the same maximum value there.
    > >>>
    > >>
    > >>On I64 V8.3:
    > >>
    > >>$ mcr sysgen show wsmax
    > >>Parameter Name Current Default Min. Max. Unit
    > >>Dynamic
    > >>-------------- ------- ------- ------- ------- ----
    > >>-------
    > >>WSMAX 1089536 131072 16384 134217728 Pagelets
    > >> internal value 68096 8192 1024 8388608 Pages
    > >>
    > >>Same maximum, but much higher default and min values. "Current" value came
    > >>from AUTOGEN with feedback, AFAIK.
    > >>

    > >
    > >
    > > Thanks for that. Ditto here for the "Current" vaalue. Surprisingly, I
    > > don't see anything (on Alpha) about WSMAX in
    > > SYS$SYSTEM:AGEN$PARAMS.REPORT, though AUTOGEN is obviously calculating
    > > it.
    > >

    >
    > The same on Itanium. I didn't set it explicitly, and there's nothing
    > in MODPARAMS.DAT or in AGEN$PARAMS.REPORT. My rx2620 came from the
    > porting workshop, and was pre-loaded with V8.2-1 (since upgraded to V8.3).
    > Maybe HP set it, or maybe AUTOGEN set it on the initial install and
    > the report is long gone.


    A look at AUTOGEN shows that it does check to see whether WSMAX is too
    large or too small, and there's a lot of code there; parameters
    affecting fluid memory are taken into account to ensure there is enough
    of that.

    Looking back at my upgrade to V8.3, WSMAX wasn't in MODPARAMS.DAT
    generated by the upgrade procedure, nor the accompanying
    AGEN$PARAMS.REPORT (or any since).

    WSMAX isn't included in AGEN$HISTORY.DAT either, so I conclude that it
    is calculated by AUTOGEN each time it is run.

    --
    Paul Sture

    Sue's OpenVMS bookmarks:
    http://eisner.encompasserve.org/~stu...bookmarks.html

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