Looking for ways to detect AWS Lambda timeouts(few seconds before timeout) in Java and to test the same

Question

My current Lambda function is calling a 3rd party web service Synchronously.This function occasionally times out (current timeout set to 25s and cannot be increased further) My code is something like:

 handleRequest(InputStream input, OutputStream output, Context context) throws IOException {
       try{
       response = calling 3rd party REST service
       }catch(Exception e){
          //handle exceptions
       }
}

1)I want to custom handle the timeout (tracking the time and handling few milli seconds before actual timeout) within my Lambda function by sending a custom error message back to the client. How can I effectively use the

context.getRemainingTimeInMillis()

method to track the time remaining while my synchronous call is running? Planning to call the context.getRemainingTimeInMillis() asynchronously.Is that the right approach? 2)What is a good way to test the timeout custom functionality ?

Answer 1

I solved my problem by increasing the Lambda timeout and invoking my process in a new thread and timing out the Thread after n seconds.

        ExecutorService service = Executors.newSingleThreadExecutor();
         try {
                Runnable r = () ->{
                        try {
                           myFunction();    
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                };
                f = service.submit(r);
                f.get(n, TimeUnit.MILLISECONDS);// attempt the task for n milliseconds
            }catch(TimeoutException toe){
                //custom logic
        }