code: private CallTree initCallTree() {
  		final CallTree callTree = new CallTree(logThreshold) {
  			@Override
  			protected void onRootStopwatchStop(CallTreeNode rootNode, Split split) {
  				CallTreeCallback.this.onRootStopwatchStop(this, split);
  			}
  		};
  		threadCallTree.set(callTree);
  		return callTree;
  	}
docs: Initializes the call tree for current thread.
  
  @return Created call tree