fixed syncing message error level; added thread library for auditing

src/blockchain_utilities/threadpool_boost.h

@@ -0,0 +1,24 @@
+#ifndef THREADPOOL_BOOST_H
+#define THREADPOOL_BOOST_H
+
+#include <boost/thread.hpp>
+#include <boost/asio.hpp>
+#include <functional>
+#include <vector>
+
+class ThreadPool {
+public:
+  explicit ThreadPool(size_t numThreads);
+  ~ThreadPool();
+  
+  void enqueue(std::function<void()> task);
+  bool isStopping() const;
+  void waitForCompletion();
+
+private:
+  boost::asio::io_service ioService;
+  boost::asio::executor_work_guard<boost::asio::io_context::executor_type> workGuard;
+  std::vector<boost::thread> workers;
+};
+
+#endif  // THREADPOOL_BOOST_H