Re: JVM memory size changing dramatically
Another good place is the Java Performance Tuning web site. They have a LOT of really good articles and spend a LOT of time on GC. The IBM developer web site also has some good articles on memory and GC. Bob On Thursday 29 July 2004 12:09 pm, Shapira, Yoav wrote: Hi, | The options for what? These: - My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - Here: http://java.sun.com/docs/hotspot/VMOptions.html. There are also related documents linked from that page that illustrate some examples on when to use which options. It boils down to a lot of trials and experimentation. Yoav Shapira - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: JVM memory size changing dramatically
On Wed, 28 Jul 2004, Dennis Dai wrote: | Can't remember where I read it but it's something like this on | NT/2k/XP/2k3 family: | | Windows is using the physical memory as cache to cache the real app | image in the swap file. So if your app has been idle for a while, it's | very likely to be swap out of the physical memory. This is regardless of | how much physical memory you have. | | Interesting approach but sometimes annoying. Yes, this is called something progressive or aggressive swapping or something: it swaps away idle physical memory even if it isn't short in it, just to have max amount of physical memory ready at any time. On windows, you'll often notice that it's a real drag to get your windows desktop going in the morning (given that it is on 24/7, of course), like every app is taking a long time to get its window up and such. This is caused by this aggressive swapping scheme. Regarding the initial question, have you turned on every column there is on the task manager? There are lots other than the inital few ones. It might be that you're looking at something like the memory actually mapped physically-column, while the image size is the same. When you get your 500 visitors, it won't go down to 5 MB - since everything is active then. But do some testing.. (!) - your app might crash for other reasons than memory. Also, you apparently say that 256 MB should be the -inital- memory allocated (-Xms256), it is actually a bit weird that it shows steadily 80, when you've asked java to pre-allocate 256 MB. You could log, now and then, the values reported by the all the Runtim.*Memory() methods (there are one extra on 1.4 than 1.3) - they give you a clues to how much mem the JVM has allocated for java. As a side note, I'll heavily recommend swapping the bad task manager for the MUCH better and information-rich process explorer from sysinternals: http://www.sysinternals.com/ntw2k/freeware/procexp.shtml (One thing that is just amazing with this, is the feature of scanning through the processes to find which process have opened/locked a file - MS themselves haven't come up with this obvious feature yet (lsof on unix).. ) Have fun! One question from me: where do you get all those other options from? Where do I get a listing of those extra-options, documentation? -- Mvh, Endre Stølsvik M[+47 93054050] F[+47 51625182] Developer @ CoreTrek AS - http://www.coretrek.com/ CoreTrek corporate portal / EIP - http://www.corelets.com/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
Hi, Good post ;) One question from me: where do you get all those other options from? Where do I get a listing of those extra-options, documentation? The options for what? Yoav - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
On Thu, 29 Jul 2004, Shapira, Yoav wrote: | One question from me: where do you get all those other options from? | Where do I get a listing of those extra-options, documentation? | | The options for what? These: - My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - Endre - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
Hi, | The options for what? These: - My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - Here: http://java.sun.com/docs/hotspot/VMOptions.html. There are also related documents linked from that page that illustrate some examples on when to use which options. It boils down to a lot of trials and experimentation. Yoav Shapira - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
But windows has enough space, 2GB memory, Dual processors, this app. is running but still Tomcat does not receive hits, what will happen if the server has up to 500 visitors concurrently, How windows will handle this? How to make sure that JVM will not goes down? -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:19 To: Tomcat Users List; [EMAIL PROTECTED] Subject: RE: JVM memory size changing dramatically Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
Only you can answer these questions by testing your application with something like Jmeter. Devise tests that replicate user behaviour and increase the load until it breaks. Then you will be able to see what it can handle and how windows copes with the load. Ta Matt -Original Message- From: Safadi, Mazin [mailto:[EMAIL PROTECTED] Sent: 28 July 2004 17:40 To: 'Tomcat Users List' Subject: RE: JVM memory size changing dramatically But windows has enough space, 2GB memory, Dual processors, this app. is running but still Tomcat does not receive hits, what will happen if the server has up to 500 visitors concurrently, How windows will handle this? How to make sure that JVM will not goes down? -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:19 To: Tomcat Users List; [EMAIL PROTECTED] Subject: RE: JVM memory size changing dramatically Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Any opinions expressed in this E-mail may be those of the individual and not necessarily the company. This E-mail and any files transmitted with it are confidential and solely for the use of the intended recipient. If you are not the intended recipient or the person responsible for delivering to the intended recipient, be advised that you have received this E-mail in error and that any use or copying is strictly prohibited. If you have received this E-mail in error please notify the beCogent postmaster at [EMAIL PROTECTED] Unless expressly stated, opinions in this email are those of the individual sender and not beCogent Ltd. You must take full responsibility for virus checking this email and any attachments. Please note that the content of this email or any of its attachments may contain data that falls within the scope of the Data Protection Acts and that you must ensure that any handling or processing of such data by you is fully compliant with the terms and provisions of the Data Protection Act 1984 and 1998. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: JVM memory size changing dramatically
as others have stated, the only way to know is to stress test your app. even without running a test, I can tell you IIS5 running on a dual CPU box cannot handle 500 concurrent requests for dynamic pages. 500 concurrent requests for static files isn't a problem. Depending on the kind of application, the maximum concurrent requests maybe as low as a dozen or as high as 50-60. Does your app make database queries? How long do the queries take? How many CPU's does the database server have? Which version of Sql Server do you run? Is the database hosted on a separate box? What kind of router are you using between the webserver and database? Is there a dedicated ethernet port and router between the two tiers? These are all important questions to ask and answer. Once you answer most of these questions, you'll be able to confidently say what your webapp can handle. good luck peter On Wed, 28 Jul 2004 16:43:29 +0100, Dale, Matt [EMAIL PROTECTED] wrote: Only you can answer these questions by testing your application with something like Jmeter. Devise tests that replicate user behaviour and increase the load until it breaks. Then you will be able to see what it can handle and how windows copes with the load. Ta Matt -Original Message- From: Safadi, Mazin [mailto:[EMAIL PROTECTED] Sent: 28 July 2004 17:40 To: 'Tomcat Users List' Subject: RE: JVM memory size changing dramatically But windows has enough space, 2GB memory, Dual processors, this app. is running but still Tomcat does not receive hits, what will happen if the server has up to 500 visitors concurrently, How windows will handle this? How to make sure that JVM will not goes down? -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:19 To: Tomcat Users List; [EMAIL PROTECTED] Subject: RE: JVM memory size changing dramatically Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: JVM memory size changing dramatically
Hi, The only good way of knowing what your setup is capable of, is testing. if you do not reach the 500 concurrent visitors mark in simulation testings (using JMeter or some ohter stress tool) you will probably not be able to serve 500 real concurrent users. Be sure to run the test over night, or at least for more than 5 or 10 minutes, as your application might be leaking some memory over time. Regarding the strange memory behaviour shown in TaskManager, when it goes up and then down, taskmanager is not showing correct information all the time. Try running tomcat in a command promt window, then watch how taskmanager reports memory statistics when you minimize the window. if memory goes steadilly up, you should check if you are reloading jsp pages, or using developement settings for the jsp sservlet. Behaviour like you described could happen if you have context-reloading set to true, then if something changes in either web.xml or WEB-INF/lib or /WEB-INF/classes directory the classloader for that context is reloaded. This can take up some memory, that usually is returned in GC. hope it helps -reynir Safadi, Mazin wrote: But windows has enough space, 2GB memory, Dual processors, this app. is running but still Tomcat does not receive hits, what will happen if the server has up to 500 visitors concurrently, How windows will handle this? How to make sure that JVM will not goes down? -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:19 To: Tomcat Users List; [EMAIL PROTECTED] Subject: RE: JVM memory size changing dramatically Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: JVM memory size changing dramatically
I don't think it's related to the IIS5, my web server is Tomcat5. how many concurrent requests related to my hardware (JVM) and tomcat threading. I have MySql server 4.0.16 (max_connections=300), and Tomcat5 both running on the same machine. -Original Message- From: Peter Lin [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:53 To: Tomcat Users List Subject: Re: JVM memory size changing dramatically as others have stated, the only way to know is to stress test your app. even without running a test, I can tell you IIS5 running on a dual CPU box cannot handle 500 concurrent requests for dynamic pages. 500 concurrent requests for static files isn't a problem. Depending on the kind of application, the maximum concurrent requests maybe as low as a dozen or as high as 50-60. Does your app make database queries? How long do the queries take? How many CPU's does the database server have? Which version of Sql Server do you run? Is the database hosted on a separate box? What kind of router are you using between the webserver and database? Is there a dedicated ethernet port and router between the two tiers? These are all important questions to ask and answer. Once you answer most of these questions, you'll be able to confidently say what your webapp can handle. good luck peter On Wed, 28 Jul 2004 16:43:29 +0100, Dale, Matt [EMAIL PROTECTED] wrote: Only you can answer these questions by testing your application with something like Jmeter. Devise tests that replicate user behaviour and increase the load until it breaks. Then you will be able to see what it can handle and how windows copes with the load. Ta Matt -Original Message- From: Safadi, Mazin [mailto:[EMAIL PROTECTED] Sent: 28 July 2004 17:40 To: 'Tomcat Users List' Subject: RE: JVM memory size changing dramatically But windows has enough space, 2GB memory, Dual processors, this app. is running but still Tomcat does not receive hits, what will happen if the server has up to 500 visitors concurrently, How windows will handle this? How to make sure that JVM will not goes down? -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:19 To: Tomcat Users List; [EMAIL PROTECTED] Subject: RE: JVM memory size changing dramatically Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: JVM memory size changing dramatically
keep in mind that even if you set the max connections to 300, it doesn't mean it can realiably handle 300 concurrent queries with good performance. I would use JMeter to stress test the database with real queries. Once you get a picture of how the queries scale in relation to the number of concurrent queries, you'll have a much better idea of the scalability of the application. It's a bit erroneous to think of scalability in terms of Tomcat5. In my biased opinion all of the major webservers are roughly equal today. the difference really comes down to how you write your application. Assuming you've take time to tune your sql queries and create the proper indexes on the tables, your queries should take 200-400ms. On a dual CPU box, a respectable throughput would be 10-20 queries per second. The chances of double or tripling that throughput on the same hardware is a matter of optimizing your database tables and denormalizing the database schema for performance. Realistically, you won't be able to handle 500 concurrent requests to the webserver without some sort of in memory cache. Without caching, no webserver will be able to handle 500 concurrent requests. I hope that helps peter On Wed, 28 Jul 2004 19:31:20 +0200, Futchi [EMAIL PROTECTED] wrote: I don't think it's related to the IIS5, my web server is Tomcat5. how many concurrent requests related to my hardware (JVM) and tomcat threading. I have MySql server 4.0.16 (max_connections=300), and Tomcat5 both running on the same machine. -Original Message- From: Peter Lin [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:53 To: Tomcat Users List Subject: Re: JVM memory size changing dramatically as others have stated, the only way to know is to stress test your app. even without running a test, I can tell you IIS5 running on a dual CPU box cannot handle 500 concurrent requests for dynamic pages. 500 concurrent requests for static files isn't a problem. Depending on the kind of application, the maximum concurrent requests maybe as low as a dozen or as high as 50-60. Does your app make database queries? How long do the queries take? How many CPU's does the database server have? Which version of Sql Server do you run? Is the database hosted on a separate box? What kind of router are you using between the webserver and database? Is there a dedicated ethernet port and router between the two tiers? These are all important questions to ask and answer. Once you answer most of these questions, you'll be able to confidently say what your webapp can handle. good luck peter On Wed, 28 Jul 2004 16:43:29 +0100, Dale, Matt [EMAIL PROTECTED] wrote: Only you can answer these questions by testing your application with something like Jmeter. Devise tests that replicate user behaviour and increase the load until it breaks. Then you will be able to see what it can handle and how windows copes with the load. Ta Matt -Original Message- From: Safadi, Mazin [mailto:[EMAIL PROTECTED] Sent: 28 July 2004 17:40 To: 'Tomcat Users List' Subject: RE: JVM memory size changing dramatically But windows has enough space, 2GB memory, Dual processors, this app. is running but still Tomcat does not receive hits, what will happen if the server has up to 500 visitors concurrently, How windows will handle this? How to make sure that JVM will not goes down? -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 17:19 To: Tomcat Users List; [EMAIL PROTECTED] Subject: RE: JVM memory size changing dramatically Hi, Windows needs additional space for other things (including possibly idle thread cleanup) and swaps your process into a paging area temporarily. It's fairly standard practice, and as you noted results in no errors, so don't worry about it. Yoav Shapira Millennium Research Informatics -Original Message- From: Futchi [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 12:11 PM To: Tomcat Users List Subject: JVM memory size changing dramatically Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows
Re: JVM memory size changing dramatically
Can't remember where I read it but it's something like this on NT/2k/XP/2k3 family: Windows is using the physical memory as cache to cache the real app image in the swap file. So if your app has been idle for a while, it's very likely to be swap out of the physical memory. This is regardless of how much physical memory you have. Interesting approach but sometimes annoying. On 7/28/2004 9:11 AM, Futchi wrote: Hi all, I am running tomcat 5 on Win2003 server, my single app. has several threads running in the background (threads loading and writing data, detecting URL connections). Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in the Tasks Manager, it keeps running stable and getting up and down between 80 and 93 MB memory size. After several hours, memory size gets down to 5 MB very fast, and then start goes up to 90 MB also fast. This change happening in about 2-3 minutes only, then it becomes stable again jumping between 80-93 MB memory size. While this happening Tomcat is up and running, also my App. is up and running. I do not have any memory error messages. I doubt it is the GC, Anybody can explain that?!!! My JAVA_OPTS as follows JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5 -XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m -Xss128k -XX:+DisableExplicitGC -- Dennis Dai [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
