Nelson Minar (nelson@media.mit.edu)
Wed, 17 Mar 1999 16:50:41 -0500 (EST)
Hello everyone, welcome to the list! We may want to delay serious discussion a couple of days until we get the list membership up, but I couldn't resist answering this now :-) Bill Foote wrote: >Nelson summarized papers and other sites related to resource >maangement in the first message in the archive. I think what he is referring to is a message I wrote for another mailing list I run on mobile code. (http://mobility.lboro.ac.uk/) Here it is. BTW, the core of this message is my own particular interest in Java resource accounting; I'm trying to do mobile agents for real, and you need resource accounting to control untrusted code. ---------------------------------------------------------------------- >I'm currently investigating what seems to be a major issue to resolve >before any mobile code can be broadly deployed : resource accounting. >Since most of the mobile environments are Java based, I'm mostly >interested in the JVM and the way it manages its threads, memory, etc. I'm very interested in this issue as well. There's been discussion of it off and on for Java, mostly under the guise of protecting against denial of service from applets. You referenced the JRes work; that's the best implementation I know to date. I'm hoping with the new JDK licensing terms it might be possible to get inside the Java environment and add resource accounting in a "good" way, rather than having to hack it in. [JRes is at http://simon.cs.cornell.edu/home/grzes/page3.html] There's some work on this issue now within the Java real time work, there's a page about that at http://developer.java.sun.com/developer/jcp/jsr_real_time.html with a link to the proposal at http://www.sdct.itl.nist.gov/~carnahan/real-time/sun/index.html This is more about CPU than memory usage, though. Finally, some references I haven't followed: http://gee.cs.oswego.edu/dl/delegation/delegation.html http://www.gr.opengroup.org/~bernadat/javaSvcGuarantees.fm.ps http://www.gr.opengroup.org/~bernadat/resSafeJava.fm.ps >While not offering a library permiting us to see what's happening >under the hood, the Java 2 (JDK 1.2) platform suggests a profiling >interface to the JVM (1) which, from what I understand, enables us to >natively monitor some of the resource allocation taking place in the >virtual machine. Now that's interesting. But would you be able to also control resource usage, or only monitor it? The new security model in Java 1.2 makes it easier to add new kinds of checks, but it still relies on the libraries themselves calling the check code first. You just might be able to control Thread, for instance, but I don't know of any way to hook all memory allocation. Another way to possibly manage this is to hook in as a JIT compiler. That must give you access to a fair amount of the internals of the machine state. But that would be an awful abuse of the compiler interface, and still might not give you the access you need. What's really needed is a clean, official interface for this stuff. There's been some talk about getting a group together to work on designing one; if that goes forward, I'll post about it to mobility. nelson@media.mit.edu . . . . . . . . http://www.media.mit.edu/~nelson/ ---------------------------------------------------------------------------- To unsubscribe (or other requests) mailto:majordomo@media.mit.edu List archives, FAQ, member list, etc. http://gee.cs.oswego.edu/dl/javares/
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