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Python logging module: logger is repeating the message more and more as I run the script

So I have been having this weird problem in my Spyder IDE (and only in Spyder).
I initialize a logger using the logging module, and each time I run the script the messages are printed in more and more times (once on the first try, twice on the second, thrice on the third, etc...). Any ideas why?
The code:
import logging
logger = logging.getLogger(__name__)
handle = logging.StreamHandler()
logger.addHandler(handle)
handle.setLevel(logging.DEBUG)
formatter = logging.Formatter(fmt='%(asctime)s - %(levelname)s - %(message)s')
handle.setFormatter(formatter)
logger.warning('Testing')
Thanks in advance!
EDIT: This is what I see in my console after two tries:
logger.warning('Testing')
2020-09-30 15:34:34,763 - WARNING - Testing
logger.warning('Testing')
2020-09-30 15:34:38,476 - WARNING - Testing
2020-09-30 15:34:38,476 - WARNING - Testing

The logging module uses a static logger object that lives in your python session. So, every time you run your script, addHandler will add a new handler to logger.handlers. You can add a line to your script that prints logger.handlers and check.
...
logger.addHandler(handle)
print(logger.handlers)
...
And every time you call logger.warning the message will be printed as many times as the number of handlers you have.
To fix this you need to remove the handler:
...
logger.warning('Testing')
logger.removeHandler(handle)
Another fix is to check if you already have a handler before adding a new one. This way you will only have one handler, and you won't need to remove it.
...
if not logger.handlers:
handle = logging.StreamHandler()
formatter = logging.Formatter(fmt='%(asctime)s - %(levelname)s - %(message)s')
handle.setFormatter(formatter)
handle.setLevel(logging.DEBUG)
logger.addHandler(handle)
...
You could also look into removing all handlers first.

How do I set a different name to an individual log handler?

I have two log handlers in my code: a StreamHandler to write INFO level logs from the same module to stdout, and a FileHandler to write more verbose, DEBUG logs to a file. This is my code:
import sys
import logging
log = logging.getLogger('mymodule')
log.setLevel(logging.DEBUG)
logf = logging.FileHandler('file.log')
logf.setFormatter(logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s'))
log.addHandler(logf)
logs = logging.StreamHandler(sys.stdout)
logs.setLevel(logging.INFO)
logs.setFormatter(logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
log.addHandler(logs)
However, I want the FileHandler to also write DEBUG info from other modules. I can achieve this if I remove the name from logging.getLogger(), but this will also affect my StreamHandler, which I only want to print output from my own module.
So is there a way to have either of the handlers use a different name?

There's a name attribute available on the base Handler class. I took a look at the Python source and doesn't look like it's used internally so you could manually set each handler to a different name.

Python using basicConfig method to log to console and file

I don't know why this code prints to the screen, but not to the file? File "example1.log" is created, but nothing is written there.
#!/usr/bin/env python3
import logging
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(message)s',
handlers=[logging.FileHandler("example1.log"),
logging.StreamHandler()])
logging.debug('This message should go to the log file and to the console')
logging.info('So should this')
logging.warning('And this, too')
I have "bypassed" this problem by creating a logging object, but it keeps bugging me why basicConfig() approach failed?
PS. If I change basicConfig call to:
logging.basicConfig(level=logging.DEBUG,
filename="example2.log",
format='%(asctime)s %(message)s',
handlers=[logging.StreamHandler()])
then all logs are in the file and nothing is displayed in the console.

Try this working fine(tested in python 2.7) for both console and file
# set up logging to file
logging.basicConfig(
filename='log_file_name.log',
level=logging.INFO,
format= '[%(asctime)s] {%(pathname)s:%(lineno)d} %(levelname)s - %(message)s',
datefmt='%H:%M:%S'
)
# set up logging to console
console = logging.StreamHandler()
console.setLevel(logging.DEBUG)
# set a format which is simpler for console use
formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
console.setFormatter(formatter)
# add the handler to the root logger
logging.getLogger('').addHandler(console)
logger = logging.getLogger(__name__)

I can't reproduce it on Python 3.3. The messages are written both to the screen and the 'example2.log'. On Python <3.3 it creates the file but it is empty.
The code:
from logging_tree import printout # pip install logging_tree
printout()
shows that FileHandler() is not attached to the root logger on Python <3.3.
The docs for logging.basicConfig() say that handlers argument is added in Python 3.3. The handlers argument isn't mentioned in Python 3.2 documentation.

Another technique using the basicConfig is to setup all your handlers in the statement and retrieve them after the fact, as in...
import logging
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(levelname)s %(module)s %(funcName)s %(message)s',
handlers=[logging.FileHandler("my_log.log", mode='w'),
logging.StreamHandler()])
stream_handler = [h for h in logging.root.handlers if isinstance(h , logging.StreamHandler)][0]
stream_handler.setLevel(logging.INFO)
More sensibly though is to construct your stream handler instance outside and configure them as standalone objects that you pass to the handlers list as in...
import logging
stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.INFO)
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(levelname)s %(module)s %(funcName)s %(message)s',
handlers=[logging.FileHandler("my_log.log", mode='w'),
stream_handler])

In the example below, you can specify the log destination based on its level. For example, the code below lets all logs over the INFO level go to the log file, and all above ERROR level goes to the console.
import logging
logging.root.handlers = []
logging.basicConfig(format='%(asctime)s : %(levelname)s : %(message)s', level=logging.INFO , filename='ex.log')
# set up logging to console
console = logging.StreamHandler()
console.setLevel(logging.ERROR)
# set a format which is simpler for console use
formatter = logging.Formatter('%(asctime)s : %(levelname)s : %(message)s')
console.setFormatter(formatter)
logging.getLogger("").addHandler(console)
logging.debug('debug')
logging.info('info')
logging.warning('warning')
logging.error('error')
logging.exception('exp')

WOOAH!
I just spent about 20 minutes being baffled by this.
Eventually I worked out that the StreamHandler was outputting to stderr, not stdout (in a 'Doze DOS screen these have the same font colour!).
This resulted in me being able to run the code perfectly OK and get sensible results, but in a pytest function things going awry. Until I changed from this:
out, _ = capsys.readouterr()
assert 'test message check on console' in out, f'out was |{out}|'
to this:
_, err = capsys.readouterr()
assert 'test message check on console' in err, f'err was |{err}|'
NB the constructor of StreamHandler is
class logging.StreamHandler(stream=None)
and, as the docs say, "If stream is specified, the instance will use it for logging output; otherwise, sys.stderr will be used."
NB it seems that supplying the level keyword does not run setLevel on the handlers: you'd need to iterate on the resulting handlers and run setLevel on each, if it matters to you.

This is a ValueError if FileHandler and StreamHandler both are present in BasicConfig function
https://docs.python.org/3/library/logging.html#logging.basicConfig
See image below:

Different logging levels for filehandler and display in Python

I am using the logging module in Python to write debug and error messages.
I want to write to file all messages of logging.DEBUG or greater.
However, I only want to print to the screen messages of logging.WARNING or greater.
Is this possible using just one Logger and one FileHandler?

As it has been mentioned, handlers are so easy to create and add that you're probably better off just using two handlers. If, however, for some reason you want to stick to one, the Python logging cookbook has a section describing more or less what you want to do: logging to both console and file, but at different levels (it even shows you how to do different formatting). It does it with a single StreamHandler rather than a FileHandler, though:
import logging
# set up logging to file - see previous section for more details
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s',
datefmt='%m-%d %H:%M',
filename='/temp/myapp.log',
filemode='w')
# define a Handler which writes INFO messages or higher to the sys.stderr
console = logging.StreamHandler()
console.setLevel(logging.INFO)
# set a format which is simpler for console use
formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
# tell the handler to use this format
console.setFormatter(formatter)
# add the handler to the root logger
logging.getLogger('').addHandler(console)
# Now, we can log to the root logger, or any other logger. First the root...
logging.info('Jackdaws love my big sphinx of quartz.')
# Now, define a couple of other loggers which might represent areas in your
# application:
logger1 = logging.getLogger('myapp.area1')
logger2 = logging.getLogger('myapp.area2')
logger1.debug('Quick zephyrs blow, vexing daft Jim.')
logger1.info('How quickly daft jumping zebras vex.')
logger2.warning('Jail zesty vixen who grabbed pay from quack.')
logger2.error('The five boxing wizards jump quickly.')
Edit: As discussed in the comments this code still generates two handlers, but "hides" one construction through the use of basicConfig(). I would strongly encourage you to create both explicitly.

You can append lots of handlers to the same logger with different loglevel, but root loglevel must be as verbose as the most verbose handler. This example log messages to file with log.debug() and log.info() to console:
log = logging.getLogger("syslog2elastic")
log.setLevel(logging.DEBUG) # this must be DEBUG to allow debug messages through
console = logging.StreamHandler()
console.setLevel(logging.INFO)
formatter = logging.Formatter("%(asctime)s.%(msecs)03d - %(name)s:%(lineno)d - %(levelname)s - %(message)s", "%Y%m%d%H%M%S")
console.setFormatter(formatter)
log.addHandler(console)
fh = RotatingFileHandler(args.logfile, maxBytes=104857600, backupCount=5)
fh.setLevel(logging.DEBUG)
formatter = logging.Formatter("%(asctime)s.%(msecs)03d - %(message)s", "%Y%m%d%H%M%S")
fh.setFormatter(formatter)
log.addHandler(fh)

No. File and Screen output means you need two handlers.

You can do this in the following way, making two loggers, one for file logging, another one for console logging. Make sure to set the root logger to the most verbose of the two.
import logging
logging.getLogger().setLevel(logging.DEBUG) # This must be as verbose as the most verbose handler
formatter = logging.Formatter(
'%(asctime)s.%(msecs)03d %(levelname)s %(module)s - %(funcName)s [%(lineno)s]: %(message)s',
datefmt='%Y-%m-%d %H:%M:%S',
)
console_logging = logging.StreamHandler()
console_logging.setLevel(logging.WARNING)
console_logging.setFormatter(formatter)
logging.getLogger().addHandler(console_logging)
file_logging = logging.FileHandler('file.log')
file_logging.setLevel(logging.DEBUG)
file_logging.setFormatter(formatter)
logging.getLogger().addHandler(file_logging)

Make a Python log file only when there are errors (using logging module)

I'd like to use the "logging" module in Python to write errors to a log file. However, I want the file to only be created when there are errors. I use the following code:
import logging
f = 'test.conf'
logger = logging.getLogger("test_logger")
logger.setLevel(logging.INFO)
ch_file = logging.FileHandler("test_logger.conf")
ch_file.setLevel(logging.ERROR)
logger.addHandler(ch_file)
ch_file.close()
ch = logging.StreamHandler()
ch.setLevel(logging.INFO)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
ch.setFormatter(formatter)
logger.addHandler(ch)
logger.info("info")
logger.warn("warning")
#logger.error("error")
When logger.error("error") is uncommented, I expect the file "test_logger.conf" to be made with the error in it. However, when the line is commented out, I find that the test_logger.conf file is still made and is empty. How can I make it so this file is NOT made unless there are errors to report?
Thanks.

You're in luck. The FileHandler has a delay parameter designed for this purpose:
ch_file = logging.FileHandler("test_logger.conf",delay=True)