Question
TCS
IN
Last activity: 29 May 2018 11:24 EDT
Difference in HEAP Usage showing in SMA and UNIX TOP command
Application Configured with 6GB Heap Memory and 1GB Perm . Observed difference in SMA heap and unix TOP command values.
SMA showing 2 GB free but when checked in UNIX Top command usage in 7GB.
Why there is this difference ?
***Edited by Moderator Marissa to update categories***
Pegasystems Inc.
IN
Hi There,
Res in top command doesnot correspond to the remaining heap size for JVM.
http://mugurel.sumanariu.ro/linux/the-difference-among-virt-res-and-shr-in-top-output/
You can use JMAP or JSTAT utility to get an snapshot of memory. They would be same as the one shown in SMA.
Thanks,
Ujjwal
TCS
IN
Thanks Ujjwal for the reply.
Observed the same heap utilization in the JConsole tool and SMA for heap. But when comparing to total utilization of the RAM from server is getting deviation.
RES in TOP command is total RAM utilizing by the application which means Heap+NonHeap. In our case the total RAM allocated for application is 7Gb (Heap 6GB + Non Heap 1GB). Observed 2GB free Heap in SMA. That means 4GB Heap was utilized , if we assume the non heap was completely occupied then the total utilized should be 6GB (Heap 4GB+NonHeap 1GB) only.
But the RAM utilization for application is 7 GB in server level.
Updated: 15 May 2018 9:56 EDT
Allianz Germany
DE
RAM utilization seen through TOP or free command will always be more than heap because your System has other background processes running other than pega . These OS processes would also consume some RAM and some level of deviation would be there.
TCS
IN
We have observed the values related to the PRPC process only. TOP is displaying the RAM utilization of all the processes individually. We referred to the PRPC process so it will not include the OS utilization. Due to the difference in calculations there could be some deviation but not this much.