Using isolcpus and taskset for a multi-threaded java process

I have isolated 1 socket from the kernel, cores isol 8-15.

I then created the following files with these values
/sys/fs/cgroup/cpuset/java/cpuset.cpus
8-15
/sys/fs/cgroup/cpuset/java/cpuset.mems
1

I then used taskset to pin the pid to the desired cores but it's not using those cpus

[root]# ps -L -p 12040 -o tid,pid,cpuid,ppid,args
TID PID CPUID PPID COMMAND
12040 12040 1 12026 /usr/java
12041 12040 7 12026 /usr/java
12042 12040 6 12026 /usr/java
12043 12040 6 12026 /usr/java
12044 12040 4 12026 /usr/java
12045 12040 7 12026 /usr/java

I've been using this page
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/resource_management_guide/sec-cpuset