Only have a threadpool the size of the allowable cores, not all of them

src/apex/threadpool.h

@@ -6,13 +6,14 @@
 #include <functional>
 #include <mutex>
 #include <condition_variable>
+#include "utils.hpp"
 
 namespace apex {
 namespace treemerge {
 
 class ThreadPool {
 public:
-    ThreadPool(uint32_t size = std::thread::hardware_concurrency()) :
+    ThreadPool(uint32_t size = my_hardware_concurrency()) :
         nthreads(size) {};
     void Start(void);
     void QueueJob(const std::function<void()>& job);

src/apex/tree.h

@@ -49,7 +49,8 @@ class node {
             return children.at(cname);
         }
         static node * buildTree(std::vector<std::vector<std::string>>& rows, node * root);
-        static size_t getSize() { return count; }
+        static size_t getSize(void) { return count; }
+        static void reset(void) { count = 0; }
 };
 
 } // namespace treemerge