Posted: 14 Mar 2017 11:39 EDT Last activity: 23 Mar 2017 6:46 EDT
'ALERT0021' is present in log which indicates that the Data Page size has exceeded 5% of the JVM heap size.
Our application is a memory intensive application and we load the required data onto Data Pages as suggested by Pega. We are trying to optimize our application and wanted to understand the below.
What is the significance of this ALERT and why is the threshold present at 5% ?
I understand this can be changed by modifying <env name="DeclarePages/MemoryUsagePercentLimit" value="5” /> in prconfig.xml . Would like to understand why the default threshold is at 5%. Also, till what percentage of JVM heap size, can Data Page sizes grow ?
Kindly explain. Thanks.
5% is a number that is big enough so that most user applications will not generate these alerts. However, it is also small enough so that you can take some action before the size of the page very likely will negatively impact the JVM.
I don't believe there is any practical limit on the size of a Data Page. Of course, the more the data page takes away from the JVM, the less there will be for everything else in your Application. You should analyze what is driving the size. You may want to redesign to make it smaller, or else feel quite comfortable with the size that it is. Based upon other things, you may want to increase the overall size of your JVM.
There is no "one-size-fits-all" response to this question.