RE: [JBoss-user] Garbage Collector: Service?
AH HA! This is precisely the trap that a lot of folks run in to with respect to the GC. That the memory remains high in an idle system for an indefinite period indicates that you indeed have reachable objects loitering around in the heap. Unfortunately forcing a GC will not release them. In fact, the existence of incremental GC pretty much eliminates any benefit for an application (short of a diagnostic tool) from executing an explicit GC. I suggest using weak references such as found in the weak hashmap. The cost is that you now have to reload objects on demand if they were collected and the reference set to null. Another approach is the memory mapped files (FileChannel) and now that we are JDK 1.4 all around I am considering moving towards that. Your data looks like a sequential in-memory stream but in fact it is being paged in and out using a fixed memory window. -Original Message- From: Muraly R [mailto:[EMAIL PROTECTED] Sent: Tue 1/27/2004 9:23 PM To: [EMAIL PROTECTED] Cc: Subject: RE: [JBoss-user] Garbage Collector: Service? Hi Rod, The application is heavily using heavy weights(like vectors and hashmaps). Though they are declared within corresponding methods only, after a particular operation, the memory shoots up and stays in that state forever. It never return to 'normal' state. Hence thought of implementing a periodic GC. I am aware of the 'best effort try' of the VM by calling the GC. I am trying various options to bring the memory to an 'affordable' state. Hope I have cleared the requirement. Thanks all for your replies and expecting MORE:-) Cheers Muraly At 12:54 27/01/2004 -0800, you wrote: Just curious, what is your objective in terms of a periodic GC call? -Original Message- From: Muraly R [mailto:[EMAIL PROTECTED] Sent: Monday, January 26, 2004 8:34 PM To: [EMAIL PROTECTED] Subject: RE: [JBoss-user] Garbage Collector: Service? Hi Heiko, Thanks for reply. Please bear my ignorance. Could you give a more detailed explanation? Did you mean writing a seperate class and deploy it as a '-service.xml' file. If then, how can I schedule this class to be run, say every 5 mins? Thanks Muraly At 09:13 23/01/2004 +0100, you wrote: Hi, Is there any particular service available in JBoss to schedule the garbage collector? use jboss.system:type=System and there the runGarbageCollector call. Heiko --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user winmail.dat
Re: [JBoss-user] Garbage Collector: Service?
Muraly, Please bear my ignorance. Could you give a more detailed explanation? try e.g. cd $JBossHome/bin twiddle invoke "jboss.system:type=System" runGarbageCollector Did you mean writing a seperate class and deploy it as a '-service.xml' file. If then, how can I schedule this class to be run, say every 5 mins? Either use a scheduler like quartz to do this or use your system cron in conjunction with twiddle. Heiko
Re: [JBoss-user] Garbage Collector: Service?
I'd agree - and I'd probably say that forcing garbage collection is likely to have an adverse effect on performance as the JVM has a much better idea of when to GC than anyone else does. With Sun's 1.4 JVM there are now several types of Garbage Collector available, and you may find some are better suited for your application than others (in particular some of them are only recommended for systems with 4+ processors). Here's some links I found useful: http://java.sun.com/j2se/1.4.2/1.4.2_whitepaper.html http://java.sun.com/docs/hotspot/index.html http://java.sun.com/docs/hotspot/gc1.4.2/index.html You may find the jvmstat useful to monitor heap usage and GC (plus is has some nice graphs!): http://developers.sun.com/dev/coolstuff/jvmstat/ Although in the end I think it's something of a black art working out which works best. -Andrew Rod Macpherson wrote: It is my understanding there is little point in an arbitrary GC call. Periodic GC calls have some benefit in terms of distributing effort over time however that is already available through JVM options. That memory shoots up is not relevant unless and until there is insufficient memory to satisfy an allocation request. At that point the GC will run and all threads are suspended within the JVM so no allocation request will occur. The GC will run as often as needed to satisfy the need for additional memory. Out of memory will occur if and only if there are indeed to many reachable references that cannot be released. I would add that the heap is divided in two so that you can run out of the so-called eden space and that can be adjusted using the JVM memory switches. Seems to be a common misconception that forcing a GC will cure out of memory problems. If anybody has knowledget that contradicts this by all means post it since this seems to be an area of frequent concern. Kind of off-topic AFA JBoss is concerned however. -Original Message- From: Muraly R [mailto:[EMAIL PROTECTED] Sent: Thursday, January 22, 2004 9:42 PM To: [EMAIL PROTECTED] Subject: [JBoss-user] Garbage Collector: Service? Hi Gurus, Is there any particular service available in JBoss to schedule the garbage collector? The reason for this question is our application is using heavy weight objects like Vector, HashTable, etc. heavily. As a result of this after a simple get query the JBoss memory shoots up and it is not returning to is normal state. Hence this query. Also, for SessionBeans(Stateful/Stateless), if the cache-policy-conf is configured as follows: cache-policy-conf min-capacity50/min-capacity max-capacity100/max-capacity remover-period600/remover-period max-bean-life600/max-bean-life overager-period300/overager-period max-bean-age300/max-bean-age resizer-period400/resizer-period max-cache-miss-period60/max-cache-miss-period min-cache-miss-period1/min-cache-miss-period cache-load-factor0.75/cache-load-factor /cache-policy-conf and if the ejbRemove() of the corresponding beans are populated with code to 'null' the object will this help. Please suggest. Cheers Muraly --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
RE: [JBoss-user] Garbage Collector: Service?
Hi Rod, The application is heavily using heavy weights(like vectors and hashmaps). Though they are declared within corresponding methods only, after a particular operation, the memory shoots up and stays in that state forever. It never return to 'normal' state. Hence thought of implementing a periodic GC. I am aware of the 'best effort try' of the VM by calling the GC. I am trying various options to bring the memory to an 'affordable' state. Hope I have cleared the requirement. Thanks all for your replies and expecting MORE:-) Cheers Muraly At 12:54 27/01/2004 -0800, you wrote: Just curious, what is your objective in terms of a periodic GC call? -Original Message- From: Muraly R [mailto:[EMAIL PROTECTED]] Sent: Monday, January 26, 2004 8:34 PM To: [EMAIL PROTECTED] Subject: RE: [JBoss-user] Garbage Collector: Service? Hi Heiko, Thanks for reply. Please bear my ignorance. Could you give a more detailed explanation? Did you mean writing a seperate class and deploy it as a '-service.xml' file. If then, how can I schedule this class to be run, say every 5 mins? Thanks Muraly At 09:13 23/01/2004 +0100, you wrote: Hi, Is there any particular service available in JBoss to schedule the garbage collector? use jboss.system:type=System and there the runGarbageCollector call. Heiko --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
Re: [JBoss-user] Garbage Collector: Service?
Hi Heiko, Thanks for the info. about quartz. Cheers Muraly At 09:26 27/01/2004 +0100, you wrote: Muraly, Please bear my ignorance. Could you give a more detailed explanation? try e.g. cd $JBossHome/bin twiddle invoke jboss.system:type=System runGarbageCollector Did you mean writing a seperate class and deploy it as a '-service.xml' file. If then, how can I schedule this class to be run, say every 5 mins? Either use a scheduler like quartz to do this or use your system cron in conjunction with twiddle. Heiko
RE: [JBoss-user] Garbage Collector: Service?
It is my understanding there is little point in an arbitrary GC call. Periodic GC calls have some benefit in terms of distributing effort over time however that is already available through JVM options. That memory shoots up is not relevant unless and until there is insufficient memory to satisfy an allocation request. At that point the GC will run and all threads are suspended within the JVM so no allocation request will occur. The GC will run as often as needed to satisfy the need for additional memory. Out of memory will occur if and only if there are indeed to many reachable references that cannot be released. I would add that the heap is divided in two so that you can run out of the so-called eden space and that can be adjusted using the JVM memory switches. Seems to be a common misconception that forcing a GC will cure out of memory problems. If anybody has knowledget that contradicts this by all means post it since this seems to be an area of frequent concern. Kind of off-topic AFA JBoss is concerned however. -Original Message- From: Muraly R [mailto:[EMAIL PROTECTED] Sent: Thursday, January 22, 2004 9:42 PM To: [EMAIL PROTECTED] Subject: [JBoss-user] Garbage Collector: Service? Hi Gurus, Is there any particular service available in JBoss to schedule the garbage collector? The reason for this question is our application is using heavy weight objects like Vector, HashTable, etc. heavily. As a result of this after a simple get query the JBoss memory shoots up and it is not returning to is normal state. Hence this query. Also, for SessionBeans(Stateful/Stateless), if the cache-policy-conf is configured as follows: cache-policy-conf min-capacity50/min-capacity max-capacity100/max-capacity remover-period600/remover-period max-bean-life600/max-bean-life overager-period300/overager-period max-bean-age300/max-bean-age resizer-period400/resizer-period max-cache-miss-period60/max-cache-miss-period min-cache-miss-period1/min-cache-miss-period cache-load-factor0.75/cache-load-factor /cache-policy-conf and if the ejbRemove() of the corresponding beans are populated with code to 'null' the object will this help. Please suggest. Cheers Muraly --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
RE: [JBoss-user] Garbage Collector: Service?
Hi, Is there any particular service available in JBoss to schedule the garbage collector? use jboss.system:type=System and there the runGarbageCollector call. Heiko --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
[JBoss-user] Garbage Collector: Service?
Hi Gurus, Is there any particular service available in JBoss to schedule the garbage collector? The reason for this question is our application is using heavy weight objects like Vector, HashTable, etc. heavily. As a result of this after a simple get query the JBoss memory shoots up and it is not returning to is normal state. Hence this query. Also, for SessionBeans(Stateful/Stateless), if the cache-policy-conf is configured as follows: cache-policy-conf min-capacity50/min-capacity max-capacity100/max-capacity remover-period600/remover-period max-bean-life600/max-bean-life overager-period300/overager-period max-bean-age300/max-bean-age resizer-period400/resizer-period max-cache-miss-period60/max-cache-miss-period min-cache-miss-period1/min-cache-miss-period cache-load-factor0.75/cache-load-factor /cache-policy-conf and if the ejbRemove() of the corresponding beans are populated with code to 'null' the object will this help. Please suggest. Cheers Muraly --- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn ___ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
