pysimpleapp 0.1.3

Threads

Open a python session with pysimpleapp installed.

Import libraries and classes:

from pysimpleapp.message import Message
from pysimpleapp.threads.examples import ExampleSingleRunThread, ExampleMultiRunThread
from queue import Queue
from threading import Thread

Threads take a name as the first argument, owner name as the second argument and an input and output queue for communication. Their use will be demonstrated shortly but you can confirm that they inherit from the threading.Thread class.

Let’s create the input and output queues and an instance of the ExampleSingleRunThread class:

in_queue = Queue()
out_queue = Queue()
single_run = ExampleSingleRunThread('Name', 'Owner', in_queue, out_queue)
isinstance(single_run, Thread) # returns True

Now, send the singe_run thread a start command. Threads in pysimpleapp often have some built in commands, but it is very easy to override these and add your own later.

It is also essential to define how you want a thread to behave through it’s main function. The ExampleSingleRunThread has been defined to print that it has run.

Put a start message in the input queue:

# Note the order of owner and name because we are sending from the owner
in_queue.put(Message('Owner', 'Name', 'THREAD_START', None))

This should print:

Running single run thread...

demonstrating that the thread has run!

You will also notice that if you send another start command, nothing happens. Single Run Threads execute once and then stop.

Next, make an instance of ExampleMultiRunThread:

multi_run = ExampleMultiRunThread('Name2', 'Owner', in_queue, out_queue)

Multi Run Threads will run until they are told to end. Test that functionality by providing several messages:

in_queue.put(Message('Owner', 'Name2', 'THREAD_START', None))
in_queue.put(Message('Owner', 'Name2', 'THREAD_START', None))
in_queue.put(Message('Owner', 'Name2', 'THREAD_START', None))

You will see that the thread has been counting how many times you asked it to run!

End the thread with another built in command:

in_queue.put(Message('Owner', 'Name2', 'THREAD_END', None))

After this, the thread has stopped and will no longer respond to messages.

This has been a very short introduction to some example threds but there is much more to come! Continue learning with the tutorials and soon you will be making your own threads for specific requirements.