Re: RAM usage of Linux-based Tomcat server
At 10:57 PM 8/30/2004 -0700, you wrote: I'm not worried about the transient memory used by the Tomcat instance for it to serve servlets. But I'm worried about the memory permanently allocated for a Tomcat instance. Eg. A servlet in a particular Tomcat instance, may load the entire database into the memory for efficiency reasons. Now this Tomcat instance requires X amount of memory to keep the database and all the stuff related to that Tomcat instance (except transient memory) to keep them in memory. And it requires additional variable amount of transient memory to serve it, that depends on the demand for that Tomcat instance. What I need to know is can I restrict the size of X? If the memory allocated permanently to a particular Tomcat instance cannot be restricted, Can I restrict the total memory allocation (ie. permanent + transient memory) for that Tomcat instance? The VM starts up with a default of 64 meg of RAM Max regardless of physical memory. You can increase this using -Xmx (with the Sun VM). For example... java -Xmx 256m Any out of memory errors you get are because the amount of memory needed by the application exceeds the maximum memory barrier of the VM. The only way around this is to get rid of memory leaks and/or increase the maximum memory for the VM. look up -Xmx on Google for more info Jake - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RAM usage of Linux-based Tomcat server PART2
Adding a question to this note: I have a maximum heap size of 768mb, and for a freshly started server, it sits at 65mb. Throughout the day, it works itself near the max. Users finish at 7pm, and first thing in the morning the server has not reclaimed *any* memory - i.e. if I want to stop Tomcat running out of memory and crashing, I need to restart the server every morning. Is this solely down to the app or what? I am running Tomcat 5.0.18, (shortly to be upgraded to 5.0.27) could issues with Tomcat .18 be causing this (there are some memory related notes in the Tomcat CHANGELOG). Thanks, Pete. At 10:57 PM 8/30/2004 -0700, you wrote: I'm not worried about the transient memory used by the Tomcat instance for it to serve servlets. But I'm worried about the memory permanently allocated for a Tomcat instance. Eg. A servlet in a particular Tomcat instance, may load the entire database into the memory for efficiency reasons. Now this Tomcat instance requires X amount of memory to keep the database and all the stuff related to that Tomcat instance (except transient memory) to keep them in memory. And it requires additional variable amount of transient memory to serve it, that depends on the demand for that Tomcat instance. What I need to know is can I restrict the size of X? If the memory allocated permanently to a particular Tomcat instance cannot be restricted, Can I restrict the total memory allocation (ie. permanent + transient memory) for that Tomcat instance? The VM starts up with a default of 64 meg of RAM Max regardless of physical memory. You can increase this using -Xmx (with the Sun VM). For example... java -Xmx 256m Any out of memory errors you get are because the amount of memory needed by the application exceeds the maximum memory barrier of the VM. The only way around this is to get rid of memory leaks and/or increase the maximum memory for the VM. look up -Xmx on Google for more info Jake - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] == This email was sent by Ethicalwebsites.co.uk. Ethicalwebsites.co.uk - Internet Solutions for the UK http://www.ethicalwebsites.co.uk/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: RAM usage of Linux-based Tomcat server
--- Jacob Kjome [EMAIL PROTECTED] wrote: At 10:57 PM 8/30/2004 -0700, you wrote: I'm not worried about the transient memory used by the Tomcat instance for it to serve servlets. But I'm worried about the memory permanently allocated for a Tomcat instance. Eg. A servlet in a particular Tomcat instance, may load the entire database into the memory for efficiency reasons. Now this Tomcat instance requires X amount of memory to keep the database and all the stuff related to that Tomcat instance (except transient memory) to keep them in memory. And it requires additional variable amount of transient memory to serve it, that depends on the demand for that Tomcat instance. What I need to know is can I restrict the size of X? If the memory allocated permanently to a particular Tomcat instance cannot be restricted, Can I restrict the total memory allocation (ie. permanent + transient memory) for that Tomcat instance? The VM starts up with a default of 64 meg of RAM Max regardless of physical memory. You can increase this using -Xmx (with the Sun VM). For example... java -Xmx 256m Any out of memory errors you get are because the amount of memory needed by the application exceeds the maximum memory barrier of the VM. The only way around this is to get rid of memory leaks and/or increase the maximum memory for the VM. look up -Xmx on Google for more info Jake Limiting memory for the JVM looks like solves my issue. Can I run different JVM per Tomcat instance on a single server? Sagara ___ Do you Yahoo!? Win 1 of 4,000 free domain names from Yahoo! Enter now. http://promotions.yahoo.com/goldrush - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: RAM usage of Linux-based Tomcat server
--- Shapira, Yoav [EMAIL PROTECTED] wrote: Hi, 1. Is it possible to know how much RAM is used by servlets by per domain basis? 2. Is it possible to specify the maximum RAM could be used by per domain basis? The domain is as example.com, my-domain.com, etc. Pretty much no to both questions if you have them within the same Tomcat instances (e.g. two Host elements), yes to both questions if you have separate Tomcat instances for your domains. And it's not a Tomcat limitation or feature, it's a JVM memory tracking issue. Hi, Yoav, thanks for the reply. I'm sorry I was not detailed enough. I'm not using Tomcat yet, but thinking to use Tomcat to offer Java/Servlets facility for couple of different domains hosted on one Linux-based physical server. Since the servlet resides in the RAM once it is loaded, the memory consumption and possible abuse is my concern. Therefore, allocating RAM and limiting to the allocated amount for different domain is what I'm interested. Thereby, I can install sufficient physical RAM in the server. I'm interested to know more about the Tomcat instances method you suggested. I have following queries regarding it and could you help me to understand it further? 1. Is it possible to run multiple Tomcat instances on the same machine? 2. How much RAM (in roughly) is required for a single or additional Tomcat instance without any servlet loaded? Assume we use latest SUN Javasoft JVM and latest Tomcat. 3. Once the RAM limit is specified to a particular Tomcat instance, what happens if they exceed the limit? Does it still continue to allocate RAM or does it give a run-time error? 4. Could you kindly explain (in very brief) where and how do I specify the RAM limit? 5. What are the issues I should be aware of and keep in mind when having multiple Tomcat instances on the same server? Kind regards Sagara ___ Do you Yahoo!? Win 1 of 4,000 free domain names from Yahoo! Enter now. http://promotions.yahoo.com/goldrush - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: RAM usage of Linux-based Tomcat server
On Mon, Aug 30, 2004 at 08:37:24PM -0700, Sagara Wijetunga wrote: : Since the servlet resides in the RAM once it is : loaded, the memory consumption and possible abuse is : my concern. There's much more to memory in a Java webapp than just the servlets. Read on: : 1. Is it possible to run multiple Tomcat instances on : the same machine? Yes. Please refer to the Tomcat docs on how to do this. : 2. How much RAM (in roughly) is required for a single : or additional Tomcat instance without any servlet : loaded? Assume we use latest SUN Javasoft JVM and : latest Tomcat. Try not to think of individual servlets; think of the webapp as a whole. You must load-test and profile your app to see how much memory it will use in a peak situation because no two webapps are the same. (i.e. there's no way someone who's never seen your app can give reliable numbers. It's all up to you.) : 3. Once the RAM limit is specified to a particular : Tomcat instance, what happens if they exceed the : limit? Does it still continue to allocate RAM or does : it give a run-time error? This has more to do with the JVM than with Tomcat. (Tomcat runs within the JVM.) You'd do well to read up on the specifics, but usually the JVM will throw an OutOfMemoryException, in which case it's up to you to repeat step 2 and profile/size. : 4. Could you kindly explain (in very brief) where and : how do I specify the RAM limit? Please see the Tomcat docs, or review the archives. This comes up a *lot*. : 5. What are the issues I should be aware of and keep : in mind when having multiple Tomcat instances on the : same server? The same considerations as with any other app: CPU and memory resources. Disk space isn't an issue (webapps, not counting the logs, don't change size at runtime) and it's a very, very rare event for a rogue JVM call to take out other processes on the machine or cause a hard crash. -QM -- software -- http://www.brandxdev.net tech news -- http://www.RoarNetworX.com - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: RAM usage of Linux-based Tomcat server
--- QM [EMAIL PROTECTED] wrote: On Mon, Aug 30, 2004 at 08:37:24PM -0700, Sagara Wijetunga wrote: : Since the servlet resides in the RAM once it is : loaded, the memory consumption and possible abuse is : my concern. There's much more to memory in a Java webapp than just the servlets. Read on: : 1. Is it possible to run multiple Tomcat instances on : the same machine? Yes. Please refer to the Tomcat docs on how to do this. : 2. How much RAM (in roughly) is required for a single : or additional Tomcat instance without any servlet : loaded? Assume we use latest SUN Javasoft JVM and : latest Tomcat. Try not to think of individual servlets; think of the webapp as a whole. You must load-test and profile your app to see how much memory it will use in a peak situation because no two webapps are the same. (i.e. there's no way someone who's never seen your app can give reliable numbers. It's all up to you.) I'm not thinking at servlet level, not even at web-app level. I'm thinking at Tomcat instance (Tomcat sever) level. I understand each Tomcat instance can have multiple web-apps and each web-app can have multiple servlets? Am I wrong? I'm not worried about the transient memory used by the Tomcat instance for it to serve servlets. But I'm worried about the memory permanently allocated for a Tomcat instance. Eg. A servlet in a particular Tomcat instance, may load the entire database into the memory for efficiency reasons. Now this Tomcat instance requires X amount of memory to keep the database and all the stuff related to that Tomcat instance (except transient memory) to keep them in memory. And it requires additional variable amount of transient memory to serve it, that depends on the demand for that Tomcat instance. What I need to know is can I restrict the size of X? If the memory allocated permanently to a particular Tomcat instance cannot be restricted, Can I restrict the total memory allocation (ie. permanent + transient memory) for that Tomcat instance? : 3. Once the RAM limit is specified to a particular : Tomcat instance, what happens if they exceed the : limit? Does it still continue to allocate RAM or does : it give a run-time error? This has more to do with the JVM than with Tomcat. (Tomcat runs within the JVM.) You'd do well to read up on the specifics, but usually the JVM will throw an OutOfMemoryException, in which case it's up to you to repeat step 2 and profile/size. Does this OutOfMemoryException means it ran out of physical memory or there are still lot more physical memory available but the limit specified to the Tomcat instance exceeded? Kind regards Sagara __ Do you Yahoo!? New and Improved Yahoo! Mail - 100MB free storage! http://promotions.yahoo.com/new_mail - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
