jhatコマンドを叩いたところ、そんなもの無いと言われた
$ jhat
Unable to locate an executable at "/Library/Java/JavaVirtualMachines/openjdk-12.0.1.jdk/Contents/Home/bin/jhat" (-1)
無い..
$ ls -l "/Library/Java/JavaVirtualMachines/openjdk-12.0.1.jdk/Contents/Home/bin"
.rwxr-xr-x@ 22k user 2 4 17:23 jaotc
.rwxr-xr-x@ 18k user 2 4 17:23 jar
.rwxr-xr-x@ 18k user 2 4 17:23 jarsigner
.rwxr-xr-x@ 18k user 2 4 17:23 java
.rwxr-xr-x@ 18k user 2 4 17:23 javac
.rwxr-xr-x@ 18k user 2 4 17:23 javadoc
.rwxr-xr-x@ 18k user 2 4 17:23 javap
.rwxr-xr-x@ 18k user 2 4 17:23 jcmd
.rwxr-xr-x@ 18k user 2 4 17:23 jconsole
.rwxr-xr-x@ 18k user 2 4 17:23 jdb
.rwxr-xr-x@ 18k user 2 4 17:23 jdeprscan
.rwxr-xr-x@ 18k user 2 4 17:23 jdeps
.rwxr-xr-x@ 18k user 2 4 17:23 jfr
.rwxr-xr-x@ 18k user 2 4 17:23 jhsdb
.rwxr-xr-x@ 18k user 2 4 17:23 jimage
.rwxr-xr-x@ 18k user 2 4 17:23 jinfo
.rwxr-xr-x@ 18k user 2 4 17:23 jjs
.rwxr-xr-x@ 18k user 2 4 17:23 jlink
.rwxr-xr-x@ 18k user 2 4 17:23 jmap
.rwxr-xr-x@ 18k user 2 4 17:23 jmod
.rwxr-xr-x@ 18k user 2 4 17:23 jps
.rwxr-xr-x@ 18k user 2 4 17:23 jrunscript
.rwxr-xr-x@ 18k user 2 4 17:23 jshell
.rwxr-xr-x@ 18k user 2 4 17:23 jstack
.rwxr-xr-x@ 18k user 2 4 17:23 jstat
.rwxr-xr-x@ 18k user 2 4 17:23 jstatd
.rwxr-xr-x@ 18k user 2 4 17:23 keytool
.rwxr-xr-x@ 18k user 2 4 17:23 pack200
.rwxr-xr-x@ 18k user 2 4 17:23 rmic
.rwxr-xr-x@ 18k user 2 4 17:23 rmid
.rwxr-xr-x@ 18k user 2 4 17:23 rmiregistry
.rwxr-xr-x@ 18k user 2 4 17:23 serialver
.rwxr-xr-x@ 103k user 2 4 17:23 unpack200
どうやら以下で変更が入って、Java SE 9以降は削除されてるっぽい.
https://bugs.openjdk.java.net/browse/JDK-8059039
これからはMATを使うのがよさそうです.
http://www.eclipse.org/mat/