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Hotspot analysis shows Unknown module for a Java application

Hello, I am trying to profile a Java application that has been run using a jar.

I was interested in hotspots but I see issues in the result the profiler pops up -

Top Hotspots
Function                    Module     CPU Time
--------------------------  ---------  --------
[Outside any known module]  [Unknown]    6.482s
func@0x4bc640               libjvm.so    0.168s
func@0x63f1a0               libjvm.so    0.134s
func@0x18ece1               libc.so.6    0.130s
func@0x5ac290               libjvm.so    0.118s
[Others]                    N/A          2.738s
 

I do see a lot of Warning as well -

amplxe: Warning: Hardware collection of CPU events is not possible on this system. Microarchitecture performance insights will not be available.
amplxe: Collection started. To stop the collection, either press CTRL-C or enter from another console window: amplxe-cl -r /home/test/r004hs -command stop.
amplxe: Warning: Cannot stop posix timer: __NR_timer_settime() system call returned -1.
amplxe: Collection detached.
amplxe: Collection stopped.
amplxe: Using result path `/home/test/r004hs'
amplxe: Executing actions 19 % Resolving information for `libnet.so'
amplxe: Warning: Cannot locate debugging information for file `/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/libnet.so'.
amplxe: Executing actions 19 % Resolving information for `libnio.so'
amplxe: Warning: Cannot locate debugging information for file `/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/libnio.so'.
amplxe: Executing actions 20 % Resolving information for `libc-dynamic.so'
amplxe: Warning: Cannot locate debugging information for file `/opt/intel/vtune_amplifier_2019.3.0.590814/lib64/pinruntime/libc-dynamic.so'.
amplxe: Warning: Cannot locate debugging information for file `/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/libjava.so'.
amplxe: Executing actions 21 % Resolving information for `libjvm.so'
amplxe: Warning: Cannot locate file `/tmp/libnetty_transport_native_epoll_x86_646067732671486024415.so (deleted)'.
amplxe: Executing actions 21 % Resolving information for `libnetty_transport_na
amplxe: Warning: Cannot locate debugging information for file `/lib/x86_64-linux-gnu/libc.so.6'.
Cannot match the module with the symbol file `/lib/x86_64-linux-gnu/libc-2.27.so'. Make sure to specify the correct path to the symbol file in the Binary/Symbol Search list of directories.
amplxe: Executing actions 21 % Resolving information for `libpthread.so.0'
amplxe: Warning: Cannot locate debugging information for file `/lib/x86_64-linux-gnu/libpthread.so.0'.
amplxe: Executing actions 22 % Resolving information for `libpthread.so.0'
amplxe: Warning: Cannot locate debugging information for file `/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so'.
amplxe: Warning: Cannot locate debugging information for file `/opt/intel/vtune_amplifier_2019.3.0.590814/lib64/libtpsstool.so'.
 

I am using OpenJDK-8 on Ubuntu 18.04 on a VM in VmWare ESXI. I understand that hardware events might not be captured at all. 

Please help me understand any lacking in the setup. Is there any general Java profiling guide I should follow?

 

Thanks

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