# Heap dump

oc exec -it <pod name> -- bash
jcmd -l
jmap -dump:[live],format=b,file=[file_path] [PID]

# Thread dump

oc exec -it <pod name> -- bash
jcmd -l
jstack -l <JAVA_PID> > jstack.out

# Copy sinopac heapdump

## 用oc dubug 連線到Java Pod所在的節點
oc debug node/<node-name>
chroot /host 
crictl ps | grep <pod-name>

#用crictl取得container id
sh-5.1# crictl ps | grep java
e5ff85230d5be       quay.io/rhn_support_jaliang/java-demo@sha256:238dd8da48f570d7a5dac6ad1e323e724dd38c231d2b1820b557fcbd68036bef            9 minutes ago       Running             java-demo                               0                   9b0f887294c66       java-demo-565798b655-wxgnk

# 用inspect檢查container所在的root filesystem位置
sh-5.1# crictl inspect --output yaml e5ff85230d5be | grep sandbox_root
sh-5.1# crictl inspect --output yaml e5ff85230d5be | grep root
          - pivot_root
          - chroot
    root:
sh-5.1# crictl inspect --output yaml e5ff85230d5be | grep root -A1
          - pivot_root
          - pkey_alloc
--
          - chroot
        - action: SCMP_ACT_ERRNO
--
    root:
      path: /var/lib/containers/storage/overlay/8e3b143b30946a4005f8d0b9b5e94d6b3d7cd8eb27a37ad2a9989b6347ecda9f/merged   # <--- 這就是該Java container所在的檔案路徑
      

# 複製一份到/home目錄
cp /var/lib/containers/storage/overlay/8e3b143b30946a4005f8d0b9b5e94d6b3d7cd8eb27a37ad2a9989b6347ecda9f/diff/tmp/heap.hprof /home/core/heap.hprof
    

# 於另一個terminal 用oc cp複製debug pod內的檔案
oc get pod -A | grep debug

oc cp -n openshift-debug-9g7bw worker-0cubtestlabpsipnq2redhatcom-debug-sqr8f:/host/home/core/heap.hprof heap.hprof