Comments on: Bottlenecks: Part 2 of 4 http://www.performanceengineer.com/blog/bottlenecks-part-2-of-4/ Software Performance Engineering & Testing Fri, 13 Aug 2010 19:46:16 -0700 http://wordpress.org/?v=2.8.4 hourly 1 By: william.louth http://www.performanceengineer.com/blog/bottlenecks-part-2-of-4/comment-page-1/#comment-26 william.louth Sun, 18 Nov 2007 10:15:49 +0000 #comment-26 You might be interested in the following blog entry I just published related to measuring object allocation costs which is important when estimating resource consumption for use cases within a software execution model constructed for the purpose of modeling performance and capacity. How much does that Object cost in the VM? http://blog.jinspired.com/?p=174 Kind regards, William Louth JXInsight Product Architect CTO, JINSPIRED "Performance Management and Problem Diagnostics for Java EE, SOA, and Grid Computing" http://www.jinspired.com You might be interested in the following blog entry I just published related to measuring object allocation costs which is important when estimating resource consumption for use cases within a software execution model constructed for the purpose of modeling performance and capacity.

How much does that Object cost in the VM?
http://blog.jinspired.com/?p=174

Kind regards,

William Louth
JXInsight Product Architect
CTO, JINSPIRED

“Performance Management and Problem Diagnostics for Java EE, SOA, and Grid Computing”
http://www.jinspired.com

]]> By: william.louth http://www.performanceengineer.com/blog/bottlenecks-part-2-of-4/comment-page-1/#comment-25 william.louth Fri, 16 Nov 2007 23:33:12 +0000 #comment-25 I meant to direct my reply to melnykenator. "Performance Management and Problem Diagnostics for Java EE, SOA, and Grid Computing" http://www.jinspired.com I meant to direct my reply to melnykenator.

“Performance Management and Problem Diagnostics for Java EE, SOA, and Grid Computing”
http://www.jinspired.com

]]> By: william.louth http://www.performanceengineer.com/blog/bottlenecks-part-2-of-4/comment-page-1/#comment-24 william.louth Fri, 16 Nov 2007 21:32:07 +0000 #comment-24 Hi Charlie, You seem to discount (or ignore) that not all memory issues are related to leaks. In fact there is a large proportion related to capacity issues. Too many concurrent requests allocating and retaining significant amounts of memory during the execution life cycle of a request. Also there is a big difference between knowing there is a memory issue and understanding why and when. OS specific tools rarely (more like never) allow sufficient correlation with application and system tasks. Context is important. Unless of course you merely what to classify an incident and not actual perform a problem analysis. Recent Blog Entry on Memory Metrics http://blog.jinspired.com/?p=33 Old Article http://www.jinspired.com/products/jxinsight/outofmemoryexceptions.html kind regards, William Louth JXInsight Product Architect CTO, JINSPIRED "Performance Management and Problem Diagnostics for Java EE, SOA, and Grid Computing" http://www.jinspired.com Hi Charlie,

You seem to discount (or ignore) that not all memory issues are related to leaks. In fact there is a large proportion related to capacity issues. Too many concurrent requests allocating and retaining significant amounts of memory during the execution life cycle of a request.

Also there is a big difference between knowing there is a memory issue and understanding why and when. OS specific tools rarely (more like never) allow sufficient correlation with application and system tasks. Context is important. Unless of course you merely what to classify an incident and not actual perform a problem analysis.

Recent Blog Entry on Memory Metrics
http://blog.jinspired.com/?p=33

Old Article
http://www.jinspired.com/products/jxinsight/outofmemoryexceptions.html

kind regards,

William Louth
JXInsight Product Architect
CTO, JINSPIRED

“Performance Management and Problem Diagnostics for Java EE, SOA, and Grid Computing”
http://www.jinspired.com

]]> By: cw http://www.performanceengineer.com/blog/bottlenecks-part-2-of-4/comment-page-1/#comment-21 cw Thu, 15 Nov 2007 14:39:36 +0000 #comment-21 Thanks for the comment. Yes, the heap size can be monitored over time to identify the existence of a memory leak, but there is a difference between a memory leak and a memory bottleneck. An application could have a memory bottleneck (that is, a heap size that is too small) but not have a memory leak. An application with a memory leak, may not have a memory bottleneck (but if left to run long enough, it will eventually become a memory bottleneck, but it could take days, depending on how bad the leak is). Either way, monitoring the verbose garbage collection data will provide more information than just heap size (before and after GC), you will also find the amount of time spent in GC, how many bytes were freed, the sizes of the different heap pools (e.g. Permament space, Tenured generation, Eden Space, etc.) Thanks for the comment. Yes, the heap size can be monitored over time to identify the existence of a memory leak, but there is a difference between a memory leak and a memory bottleneck. An application could have a memory bottleneck (that is, a heap size that is too small) but not have a memory leak. An application with a memory leak, may not have a memory bottleneck (but if left to run long enough, it will eventually become a memory bottleneck, but it could take days, depending on how bad the leak is).

Either way, monitoring the verbose garbage collection data will provide more information than just heap size (before and after GC), you will also find the amount of time spent in GC, how many bytes were freed, the sizes of the different heap pools (e.g. Permament space, Tenured generation, Eden Space, etc.)

]]> By: melnykenator http://www.performanceengineer.com/blog/bottlenecks-part-2-of-4/comment-page-1/#comment-20 melnykenator Thu, 15 Nov 2007 11:27:25 +0000 #comment-20 I prefer to monitor JVM memory utilization by using the HEAP SIZE parameter (value). By monitoring free HEAP SIZE it's easy to determine memory leaks in Java application. If free HEAP SIZE is decreased over time it's a notification that something wrong with memory utilization. I prefer to monitor JVM memory utilization by using the HEAP SIZE parameter (value). By monitoring free HEAP SIZE it’s easy to determine memory leaks in Java application. If free HEAP SIZE is decreased over time it’s a notification that something wrong with memory utilization.

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