 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Java Forum / General / October 2007How to limit and change CPU and memory of a thread?
Dear all, is it possible to create a thread with limited memory and limited clock cycles? I guess this is highly dependent on the operating system and the virtual machine. For example, it seems to be possible to pose a memory limit if a Java program is started from the console under Linux (options -Xmx and - Xss). What other possibilities are there? Thank you, Ulrich > Dear all, > [quoted text clipped - 9 lines] > > Ulrich You can limit the heap size when you start the JVM, but not memory used by an individual thread. Memory isn't really owned by a thread. Once allocated any thread can access it. As far as CPU goes.. there really isn't any way to limit it. You could have a second thread that watches how much CPU has been used and does some action if it gets past a certain limit, but I don't think you are looking for this. What you probably want is for a thread to use no more than 10% of the CPU over some time interval. I don't think there is a way to do this in Java. I've been looking at some of these same issues myself and Java just doesn't have a lot of capability when it comes to severely limiting a process. I did figure out a way to limit a Java process to only one thread. You create a custom class loader for it and check for the class "java.lang.Thread". If it tries to instantiate one then throw an exception. I haven't actually tried it, but I think it would work. You are probably writing the code you are trying to limit, so this doesn't really apply to you. Good luck.  SignatureKenneth P. Turvey <kt-usenet@squeakydolphin.com> On Oct 29, 7:53 pm, "Kenneth P. Turvey" <kt-use...@squeakydolphin.com> wrote: > What you probably want is for a thread to use no more than 10% of the CPU > over some time interval. I don't think there is a way to do this in Java. that's bad > You are probably writing the code you are trying to limit, so this doesn't > really apply to you. Actually, I don't write the programs I'd like to limit. As part of the EU project MUSIC (www.music-ist.eu), I'm developing a method, called divide and conquer (D&C), to distribute (parts of) applications onto an ensemble of devices. As a result, otherwise unrelated, third- party applications can end up on the same device, thus competing for memory and CPU. (Check out Publications > Publications related to MUSIC > Divide and Conquer on the MUSIC portal). D&C will assign resources to applications. Because control is better than confidence, it is desirable that D&C can limit the resources and is able to change these limits later on. Of course, for the purpose of research it is OK to simply assign the limits and assume that the applications will follow them. But I'd prefer to have at least one demonstrator with actual control over the resources, even if this would work only for one specific hardware/software combination. Any suggestions welcome. Ulrich > Any suggestions welcome. Since you write "any": I remember having read about research concerned with the fitness of Java for real time applications. Perhaps the search engine of your choice finds something for +java +real +time. (Mine does). > > Any suggestions welcome. > > Since you write "any": I remember having read about research concerned > with the fitness of Java for real time applications. Perhaps the > search engine of your choice finds something for +java +real +time. > (Mine does). Thanks for pointing me to Java SE Real Time. That seems to be what I need. I started a new thread with questions about Java SE Real Time but feel free to point me to other information within this thread. Thank you, Ulrich > Thanks for pointing me to Java SE Real Time. That seems to be what I > need. I started a new thread with questions about Java SE Real Time > but feel free to point me to other information within this thread. Unfortunately I can't. The only thing I know is that something like "Java SE Real Time" exists (though I forgot the exact name) and that "real time" somehow implies management of CPU ressources. So I thought I could suggest you research in that direction. Hope you find something useful. > Unfortunately I can't. The only thing I know is that something like > "Java SE Real Time" exists (though I forgot the exact name) and that > "real time" somehow implies management of CPU ressources. So I thought > I could suggest you research in that direction. Hope you find > something useful. Just to add to the store of knowledge, strictly speaking a "real-time" system is one that makes guarantees about service time. Thus you know that a context switch can take no more than some time epsilon, for example. That epsilon could be large as long as it's guaranteed. Naturally the shorter the epsilon, the more responsive and generally useful is the real-time system. The key feature of real-time systems is determinism. For non-real-time systems, no matter how long the wait, something can take longer. You just cannot be sure. With real-time systems you are sure. SignatureLew >is it possible to create a thread with limited memory and limited >clock cycles? I guess this is highly dependent on the operating >system and the virtual machine. Objects don't belong to threads. There is a common pool of objects. To get the effect you want you would have to put a quota system into your various constructors. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.