Question

How do you nicely capture exceptions in Python threads?

If you have a threaded python app sys.excepthook does not capture errors in children.

When a child raises an exception the parent will continue to run without any problems thus making debugging a bit difficult.

Answer 1

import os
import sys
import signal
import string
import threading


# capture Exceptions
def except_catch(type, value, track, thread):
  import traceback

  rawreport = traceback.format_exception(type, value, track)
  report = "\n" . join(rawreport)

  errorlog = open("errors.log", "a")

  if thread != "":
    errorlog.write("Exception in thread: " + thread + "\n\n")

  errorlog.write(("%s\n" + "-" * 30 + "\n\n") % report)

  errorlog.close()
sys.excepthook = except_catch


# capture KeyboardInterrupt
def interrupt_catch(signal, frame):
  print ""
  os._exit(1)
signal.signal(signal.SIGINT, interrupt_catch)


# all your threaded code here
def whatever_threaded_function():
  try:
    a = 1 / 0

  except:
    exc_type, exc_value, exc_traceback = sys.exc_info()
    except_catch(exc_type.__name__, exc_value, exc_traceback, threading.current_thread().name)


threading.Thread(target=whatever_threaded_function).start()