tags: #python #threading #evdev

[docs](https://docs.python.org/3/library/threading.html)
#Examples
From [here](https://www.pythontutorial.net/python-concurrency/python-threading/)
```python
from time import sleep, perf_counter
from threading import Thread


def task():
    print('Starting a task...')
    sleep(1)
    print('done')


start_time = perf_counter()

# create two new threads
t1 = Thread(target=task)
t2 = Thread(target=task)

# start the threads
t1.start()
t2.start()

# wait for the threads to complete
t1.join()
t2.join()
```
## Event listener example
This uses one thread per `/dev/input/event*` file and prints out what events happen and which `/dev` node they come from.
```python
#!/usr/bin/python
import struct
import time
import sys
from glob import glob
from threading import Thread

def main():
  threads = {}
  nodes = glob("/dev/input/event*")+glob("/dev/input/mouse*")+glob("/dev/input/mice")
  #threads = {node:start_thread(node) for node in inputs}
  print(nodes)
  for node in nodes:
    print(node)
    threads[node] = start_thread(node)
  #for n,t in threads.items():
  #  t.join()

def start_thread(node):
  print(node)
  thread = Thread(target=listen,args=(node,))
  thread.start()
  return thread

def listen(node):
  try:
    listen1(node)
  except KeyboardInterrupt:
    print("Ctrl-C")
    exit(0)

def listen1(node):
  """
  FORMAT represents the format used by linux kernel input event struct
  See https://github.com/torvalds/linux/blob/v5.5-rc5/include/uapi/linux/input.h#L28
  Stands for: long int, long int, unsigned short, unsigned short, unsigned int
  """
  FORMAT = 'llHHI'
  EVENT_SIZE = struct.calcsize(FORMAT)

  #open file in binary mode
  in_file = open(node, "rb")

  event = in_file.read(EVENT_SIZE)

  while event:
      (tv_sec, tv_usec, type, code, value) = struct.unpack(FORMAT, event)

      if type != 0 or code != 0 or value != 0:
          print("%s: Event type %u, code %u, value %u at %d.%d" % \
              (node, type, code, value, tv_sec, tv_usec))
      else:
          # Events with code, type and value == 0 are "separator" events
          print("===========================================")

      event = in_file.read(EVENT_SIZE)

  in_file.close()

if __name__ == "__main__":
  main()
```