no-administration heap?

Keith Holdaway Keith.Holdaway at
Thu Feb 28 22:44:32 UTC 2008


I am trying to remotely connect to a running VM with visualgc.

Here is the DOS command from my shell on the box containing visualgc 3.0_b07

C:\Documents and Settings\kehold>visualgc 4664 at 1000
Exception in thread "main" java.lang.NullPointerException

I have kicked off a VM with jps - LVMID 4664 on the remote box AMDSRV4.

I can run visualgc locally - I have run rmiregistry and established a jstatd.all.policy file on the remote box:

grant codebase "file:${java.home}/../lib/tools.jar" {

Any ideas? The local box is 32 bit Hotspot; the remote box a 64 bit running Hotspot.

Keith R Holdaway
Java Development Technologies

SAS The Power to Know

Carpe Diem

-----Original Message-----
From: hotspot-gc-dev-bounces at [mailto:hotspot-gc-dev-bounces at] On Behalf Of Colin Walters
Sent: Thursday, February 28, 2008 4:59 PM
To: Florian Weimer
Cc: hotspot-gc-dev at
Subject: Re: no-administration heap?

On Thu, Feb 28, 2008 at 4:20 PM, Florian Weimer <fw at> wrote:
>  At least on Linux, the problem is that there is no documented API to
>  reserve address space (so that no other mappings end up there) without
>  actually allocating backing store.  MAP_NORESERVE does not work as
>  documented.

Ah, I see.  So this problem is essentially blocked on the lack of a
sufficient/documented Linux kernel interface?
Do other operating systems (Windows, Solaris) provide a good enough
interface for OpenJDK?

I'm assuming changing the collector to not require a continuous
address space would be too invasive?

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