While building a generic load testing toolkit, I found it useful to be able to use a standard invocation framework for running a thread class that contains the actual application code to be stress tested. However, I had some problems determining how to dynamically create a set of threads when I didn’t know the class ahead of time.<\/p>\n
What is below is a simple framework to get you started. <\/p>\n
\r\npublic class loadUnknownThreadedClass {\r\n\r\n public static void main(String args[]) throws Exception{\r\n\r\n Thread[] threads = new Thread[5];\r\n\r\n Class tmp = Class.forName(args[0]);\r\n for(int i = 0;i < 5;i++) {\r\n threads[i] = new Thread((Runnable)tmp.newInstance());\r\n threads[i].start();\r\n }\r\n }\r\n}\r\n\r\nclass classA implements Runnable {\r\n Thread t;\r\n\r\n classA() {\r\n t = new Thread(this);\r\n }\r\n public void run () {\r\n System.out.println(\"in classA\");\r\n }\r\n}\r\n\r\nclass classB implements Runnable {\r\n Thread t;\r\n\r\n classB() {\r\n t = new Thread(this);\r\n }\r\n public void run () {\r\n System.out.println(\"in classB\");\r\n }\r\n}\r\n<\/pre>\nThe really important piece is below:<\/p>\n
\r\n Class tmp = Class.forName(args[0]);\r\n threads[i] = new Thread((Runnable)tmp.newInstance());\r\n<\/pre>\nThis creates a class on the fly for what you want to dynamically run in a thread. It then casts a new instance of this to a Runnable object, which is required by the Thread class constructor.<\/p>\n
Sample output is shown below.<\/p>\n
\r\nemgrid01:oracle:emprod1:\/home\/oracle>java loadUnknownThreadedClass classA\r\nin classA\r\nin classA\r\nin classA\r\nin classA\r\nin classA\r\nemgrid01:oracle:emprod1:\/home\/oracle>java loadUnknownThreadedClass classB\r\nin classB\r\nin classB\r\nin classB\r\nin classB\r\nin classB\r\nemgrid01:oracle:emprod1:\/home\/oracle>\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"While building a generic load testing toolkit, I found it useful to be able to use a standard invocation framework for running a thread class that contains the actual application code to be stress tested. However, I had some problems…<\/p>\n