How to check java version of a running java process used

Question

I created a web project used spring boot and deployed it in remote server, and it's default JDK is

 echo $JAVA_HOME
/usr/local/jdk1.7.0_72

because I used java 8 in my project, so before starting my project, I explicitly exec below command

 export JAVA_HOME="/usr/local/jdk1.8.0_65"

then start my project

./myapp.jar

but when I exec below command

java -version
java version "1.7.0_72"
Java(TM) SE Runtime Environment (build 1.7.0_72-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.72-b04, mixed mode)

I am a little confused, I'm not sure which jdk version my project actually used? That is there is a java process

jps -l
17429 /var/myapp.jar

How do I know which java version it is used?

Thanks @frant.hartm

# ps aux | grep 17429
root     17429  0.4  6.7 5995260 1104984 pts/13 Sl  19:16   0:29 /usr/local/jdk1.8.0_65/bin/java -Dsun.misc.URLClassPath.disableJarChecking=true -Dserver.port=8081 -jar /var/myapp.jar

# jcmd 17429 VM.version
17429:
Java HotSpot(TM) 64-Bit Server VM version 25.65-b01
JDK 8.0_65

Answer 1

Use jcmd:

jcmd process_id VM.version

$ jcmd 9619 VM.version
9619:
Java HotSpot(TM) 64-Bit Server VM version 24.80-b11
JDK 7.0_80

Alternatively, you can use ps to find out which java binary was used:

ps aux | grep 9619
user  9619  0.0  0.5 4031224 82480 ?       Sl   12:31   0:01 /usr/lib/jvm/java-7-oracle/bin/java -cp /usr/lib/jvm