We have a pod running only a JVM process. The JVM memory occupies less memory compared to the memory occupied by Pod.
Below is the output of jmap -heap <PID>
Attaching to process ID 8, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.252-b14
using thread-local object allocation.
Garbage-First (G1) GC with 1 thread(s)
Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 536870912 (512.0MB)
NewSize = 1363144 (1.2999954223632812MB)
MaxNewSize = 318767104 (304.0MB)
OldSize = 5452592 (5.1999969482421875MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 100663296 (96.0MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 16777216 (16.0MB)
Heap Usage:
G1 Heap:
regions = 32
capacity = 536870912 (512.0MB)
used = 138141888 (131.74237060546875MB)
free = 398729024 (380.25762939453125MB)
25.730931758880615% used
G1 Young Generation:
Eden Space:
regions = 7
capacity = 318767104 (304.0MB)
used = 117440512 (112.0MB)
free = 201326592 (192.0MB)
36.8421052631579% used
Survivor Space:
regions = 1
capacity = 16777216 (16.0MB)
used = 16777216 (16.0MB)
free = 0 (0.0MB)
100.0% used
G1 Old Generation:
regions = 2
capacity = 201326592 (192.0MB)
used = 3924160 (3.74237060546875MB)
free = 197402432 (188.25762939453125MB)
1.9491513570149739% used
8145 interned Strings occupying 771960 bytes.
As you can see the JVM heap uses only 131MB but the pod memory consumption is around 450MB.
Below is the JVM args
java -Xmx512m -Xms128m -XX:MetaspaceSize=96m -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:G1HeapRegionSize=16M -XX:MinMetaspaceFreeRatio=50 -XX:MaxMetaspaceFreeRatio=80 -jar app.jar
The Java version that we are using is container aware. What could be the reason for such a gap in memory consumptions?
Update 1: Added pod yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2020-04-30T18:58:03Z"
labels:
pod-template-hash: 5c85b85966
release: app-365b18d80ba58451c00b554a3429c9af-local
name: pod-name
namespace: default
resourceVersion: "26701471"
spec:
containers:
- env:
- name: LOG_LEVEL
value: INFO
- name: POD_NAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: metadata.name
image: repo/name:tag
imagePullPolicy: Always
name: container-name
resources:
limits:
memory: 640Mi
requests:
cpu: 100m
memory: 512Mi
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
volumeMounts:
- mountPath: /var/run/secrets/kubernetes.io/serviceaccount
name: default-token-bwksb
readOnly: true
dnsPolicy: ClusterFirst
enableServiceLinks: true
imagePullSecrets:
- name: pull-secret
priority: 0
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
serviceAccount: default
serviceAccountName: default
terminationGracePeriodSeconds: 30
tolerations:
- effect: NoExecute
key: node.kubernetes.io/not-ready
operator: Exists
tolerationSeconds: 300
- effect: NoExecute
key: node.kubernetes.io/unreachable
operator: Exists
tolerationSeconds: 300
volumes:
- name: default-token-bwksb
secret:
defaultMode: 420
secretName: default-token-bwksb
The base image is azul/zulu-openjdk:8
Update 2: Added DockerFile
FROM azul/zulu-openjdk:8
RUN apt update && apt dist-upgrade -y
WORKDIR /code
COPY ./build/libs/APP.jar ./
COPY ./docker/config config
CMD java -Xmx512m -Xms128m -XX:MetaspaceSize=96m -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:G1HeapRegionSize=16M -XX:MinMetaspaceFreeRatio=50 -XX:MaxMetaspaceFreeRatio=80 -jar APP.jar
