A new ThreadGroup is created each time the DefaultExecutorFactory#getExecutor() is called:

https://github.com/infinispan/infinispan/blob/14.0.16.Final/core/src/main/java/org/infinispan/executors/DefaultExecutorFactory.java#L49

      if (blocking == null) {
         threadGroup = Thread.currentThread().getThreadGroup();
      } else {
         threadGroup = Boolean.parseBoolean(blocking) ? new BlockingThreadFactory.ISPNBlockingThreadGroup(threadNamePrefix + "-group") :
               new NonBlockingThreadFactory.ISPNNonBlockingThreadGroup(threadNamePrefix + "-group");
      }
...
          Thread th = new Thread(threadGroup, r, threadName);

The context of the memory leak is that during each application redeployment in Wildfly / EAP, a new instances of ISPNBlockingThreadGroup & ISPNNonBlockingThreadGroup plus some objects around those are created, and these are never cleared so they accumulate.

See JBEAP-25513 for details on how to reproduce.

Besides the fact that the ThreadGroup is never cleared up and introduces a memory leak, the group has always the same name, so it would perhaps be better to create it only once a then reuse this single instance?

Alternatively the group could maybe be discarded at some point (not sure when)?