Q:

Complicated android multithreading problem, looking for some guidance

New to stackoverflow, been very helpful searching, but alas the time has come to ask a question.
I am trying to use an android 2.2 single core phone to do some research.  I have implemented an algorithm that does quite a few calculations and produces a lot of data.  These data must be processed, and the solution presented back to a client app within a 40ms time frame, then process again with new state data coming from the client.  Also, the result of the calculations must be stored to the SD card as a data log. So being new to multithreading and android both, what should I use to do the following in my app:  (As a side note, this phone, when in research mode is not intended to be used as a phone, phone will be in airplane mode with wireless off, and all apps that can be turned off will be turned off, and there is no need for UI display or interaction once it is up and running...)

need to process packets coming in over adb on serial port, these packets are state data that the program needs to perform its calcs on.  These packets will be coming every 40ms, so I planned on using their arrival to trigger the start of the processing.
need to know if the algorithm is taking longer than 40ms and cancel it if so and send a message back on the serial port that it overran.
the calculation results need to be sent back over the serial connection via tcp and adb
The calculation intermediate data need to be recorded to SD.  This can be quite a lot of data, on order of 140k, every 40ms.

So I have had trouble getting all the pieces together.  I can't get my head around how a single core is going to keep up with all this going on at once?
So here is my thought, please tell me if I am headed in the right path.  I am not asking for you to solve my problem, only any advice on how to break this beast down:

So i start a service to process the tcp packets coming in from the client
Use a service bound to the main worker thread to handle writes to the SD card

So assuming this setup, can i make the algorithm part of this somewhat deterministic so that it always runs if it gets a new tcp packet, and preempts the SD write going on in the background?
Argh...should have picked something simpler for my first program
Thanks.

A:

Yes I think you are right, that it would be better to pick something easier for your first App ;) 
But as far as I understand what you are trying to do, I don't think, that you need asynchronous multiprocessing. You get some data want to process it and pass a result. I think a HandlerThread is exactly what you are looking for. It is able to recieve Messages
with data inside. You send them to the Handler and process them in an overridden handleMessage(Message m) method. So everytime you recive a Message you could just log the Time
and see if the last one is older than your limit. If it is, you could just throw the Message or the whole queue, or send a Message to your serial-port inicating the overflow.
This could be implemented as you suggest in a Service. Another HandlerThread can be started with Thread.PRIORITY_BACKGROUND to write everything to SD. 
You can send Messages even very compfortable if you apply a Messenger to the Handlers

