private Integer getThreads(ModelElement clusterElem) {
           ModelElement tuning = clusterElem.child("tuning");
           if (tuning == null) {
               return null;
           }
           ModelElement threads = tuning.child("persistence-threads");
           if (threads == null) {
               return null;
           }

           Integer count = threads.integerAttribute("count");
           if (count != null) {
               return count;
           }

           // Backward compatible fallback
           int numThreads = 0;
           for (ModelElement thread : threads.subElements("thread")) {
               count = thread.integerAttribute("count");
               numThreads += (count == null) ? 1 : count;
           }

           return numThreads;
       }
Serves stor-filestor for storage clusters.
config-model/src/main/java/com/yahoo/vespa/model/content/storagecluster/FileStorProducer.java