>>>>> "Timothy" == Timothy Reaves <[EMAIL PROTECTED]> writes:
>> Q2: is there any upper limit for -Xms and -Xmx values, or can
>> I use whatever value I want such as -Xms700m and
>> -Xmx2g (suppose "m" and "g" are available)?
> There is no upper limit.
Au contraire. There is not _supposed_ to be, no.
But, in fact, on current 32-bit Linux systems there is a 2GB limit.
See http://developer.java.sun.com/developer/bugParade/bugs/4435069.html
The same holds true on Solaris for Intel. See
http://developer.java.sun.com/developer/bugParade/bugs/4385914.html
On other platforms, Solaris on SPARC, at least, there is not supposed to
be a limit. But once again, it doesn't work for me, at least not with
the latest 1,3,1RC2.
On a 64-bit enabled Solaris 8 system with 4GB, top indicates:
=> Memory: 4096M real, 3801M free, 8002M swap free
and we get:
=> $ ./j2sdk1_3_1sparc/bin/java -version
=> java version "1.3.1-rc2"
=> Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-rc2-b23)
=> Java HotSpot(TM) Client VM (build 1.3.1-rc2-b23, mixed mode)
but if we try:
=> $ ./j2sdk1_3_1sparc/bin/java -mx2g -version
=> Error occurred during initialization of VM
=> Could not reserve enough space for object heap
Of course, one would like to actually run an application that uses more
than 2GB, not just check the version number. Those fail for me too.
It is easy to write a C program that can malloc more, but java doesn't
seem to like anything over around -mx1800m (yet.) The bug reports seem
to indicate it is a HotSpot limitation.
Note that those bug reports claim to be "closed, fixed", but the text
of the latter report seems to indicate the fix may be to documentation
noting the limitation. The latter hints at some intrinsic limitations
on Windows.
Meanwhile I'm trying to refactor our application to get by with less.
--
Jonathan Doughty The MITRE Corporation [EMAIL PROTECTED]
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