Python run with timeout

Saved searches

Use saved searches to filter your results more quickly

You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Reload to refresh your session. You switched accounts on another tab or window. Reload to refresh your session.

Python module which allows you to specify timeouts when calling any existing function, and support for stoppable threads

License

kata198/func_timeout

This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Sign In Required

Please sign in to use Codespaces.

Launching GitHub Desktop

If nothing happens, download GitHub Desktop and try again.

Launching GitHub Desktop

If nothing happens, download GitHub Desktop and try again.

Launching Xcode

If nothing happens, download Xcode and try again.

Launching Visual Studio Code

Your codespace will open once ready.

There was a problem preparing your codespace, please try again.

Latest commit

Git stats

Files

Failed to load latest commit information.

README.md

Python module to support running any existing function with a given timeout.

This is the function wherein you pass the timeout, the function you want to call, and any arguments, and it runs it for up to #timeout# seconds, and will return/raise anything the passed function would otherwise return or raise.

def func_timeout(timeout, func, args=(), kwargs=None): ''' func_timeout - Runs the given function for up to #timeout# seconds. Raises any exceptions #func# would raise, returns what #func# would return (unless timeout is exceeded), in which case it raises FunctionTimedOut @param timeout - Maximum number of seconds to run #func# before terminating @param func - The function to call @param args - Any ordered arguments to pass to the function @param kwargs - Keyword arguments to pass to the function. @raises - FunctionTimedOut if #timeout# is exceeded, otherwise anything #func# could raise will be raised @return - The return value that #func# gives ''' 

So, for esxample, if you have a function «doit(‘arg1’, ‘arg2’)» that you want to limit to running for 5 seconds, with func_timeout you can call it like this:

from func_timeout import func_timeout, FunctionTimedOut . try: doitReturnValue = func_timeout(5, doit, args=('arg1', 'arg2')) except FunctionTimedOut: print ( "doit('arg1', 'arg2') could not complete within 5 seconds and was terminated.\n") except Exception as e: # Handle any exceptions that doit might raise here 

This is a decorator you can use on functions to apply func_timeout.

Takes two arguments, «timeout» and «allowOverride»

If «allowOverride» is present, an optional keyword argument is added to the wrapped function, ‘forceTimeout’. When provided, this will override the timeout used on this function.

The «timeout» parameter can be either a number (for a fixed timeout), or a function/lambda. If a function/lambda is used, it will be passed the same arguments as the called function was passed. It should return a number which will be used as the timeout for that paticular run. For example, if you have a method that calculates data, you’ll want a higher timeout for 1 million records than 50 records.

@func_set_timeout(2.5) def myFunction(self, arg1, arg2): . 

Exception raised if the function times out.

Has a «retry» method which takes the following arguments:

* No argument - Retry same args, same function, same timeout * Number argument - Retry same args, same function, provided timeout * None - Retry same args, same function, no timeout 

func_timeout will run the specified function in a thread with the specified arguments until it returns, raises an exception, or the timeout is exceeded. If there is a return or an exception raised, it will be returned/raised as normal.

If the timeout has exceeded, the «FunctionTimedOut» exception will be raised in the context of the function being called, as well as from the context of «func_timeout». You should have your function catch the «FunctionTimedOut» exception and exit cleanly if possible. Every 2 seconds until your function is terminated, it will continue to raise FunctionTimedOut. The terminating of the timed-out function happens in the context of the thread and will not block main execution.

StoppableThread is a subclass of threading.Thread, which supports stopping the thread (supports both python2 and python3). It will work to stop even in C code.

The way it works is that you pass it an exception, and it raises it via the cpython api (So the next time a «python» function is called from C api, or the next line is processed in python code, the exception is raised).

You can use StoppableThread one of two ways:

As a Parent Class

Your thread can extend func_timeout.StoppableThread.StoppableThread and implement the «run» method, same as a normal thread.

from func_timeout.StoppableThread import StoppableThread class MyThread(StoppableThread): def run(self): # Code here return 

Then, you can create and start this thread like:

myThread = MyThread() # Uncomment next line to start thread in "daemon mode" -- i.e. will terminate/join automatically upon main thread exit #myThread.daemon = True myThread.start() 

Then, at any time during the thread’s execution, you can call .stop( StopExceptionType ) to stop it ( more in «Stopping a Thread» below

Direct Thread To Execute A Function

Alternatively, you can instantiate StoppableThread directly and pass the «target», «args», and «kwargs» arguments to the constructor

myThread = StoppableThread( target=myFunction, args=('ordered', 'args', 'here'), kwargs= < 'keyword args' : 'here' >) # Uncomment next line to start thread in "daemon mode" -- i.e. will terminate/join automatically upon main thread exit #myThread.daemon = True myThread.start() 

This will allow you to call functions in stoppable threads, for example handlers in an event loop, which can be stopped later via the .stop() method.

The StoppableThread class (you must extend this for your thread) adds a function, stop, which can be called to stop the thread.

def stop(self, exception, raiseEvery=2.0): ''' Stops the thread by raising a given exception. @param exception - Exception to throw. Likely, you want to use something that inherits from BaseException (so except Exception as e: continue; isn't a problem) This should be a class/type, NOT an instance, i.e. MyExceptionType not MyExceptionType() @param raiseEvery Default 2.0 - We will keep raising this exception every #raiseEvery seconds, until the thread terminates. If your code traps a specific exception type, this will allow you #raiseEvery seconds to cleanup before exit. If you're calling third-party code you can't control, which catches BaseException, set this to a low number to break out of their exception handler. @return ''' 

The «exception» param must be a type, and it must be instantiable with no arguments (i.e. MyExceptionType() must create the object).

Consider using a custom exception type which extends BaseException, which you can then use to do basic cleanup ( flush any open files, etc. ).

The exception type you pass will be raised every #raiseEvery seconds in the context of that stoppable thread. You can tweak this value to give yourself more time for cleanups, or you can shrink it down to break out of empty exception handlers ( try/except with bare except ).

Notes on Exception Type

It is recommended that you create an exception that extends BaseException instead of Exception, otherwise code like this will never stop:

while True: try: doSomething() except Exception as e: continue 

If you can’t avoid such code (third-party lib?) you can set the «repeatEvery» to a very very low number (like .00001 ), so hopefully it will raise, go to the except clause, and then raise again before «continue» is hit.

You may want to consider using singleton types with fixed error messages, so that tracebacks, etc. log that the call timed out.

class ServerShutdownExceptionType(BaseException): def __init__(self, *args, **kwargs): BaseException.__init__(self, 'Server is shutting down') 

This will force ‘Server is shutting down’ as the message held by this exception.

I’ve tested func_timeout with python 2.7, 3.4, 3.5, 3.6, 3.7. It should work on other versions as well.

Works on windows, linux/unix, cygwin, mac

About

Python module which allows you to specify timeouts when calling any existing function, and support for stoppable threads

Источник

Timeout Function in Python 3

Have you ever implemented a function that has to stop its execution after certain period of time? It is not as easy as it sounds, is it? I had to develop such functionality for a customer who had a requirement that one activity shouldn’t take more than 180 seconds to execute. There are two approaches to achieve this behavior. The first one is to use threads and the second one, to use processes. The second one is better in my opinion but let me first start with the threads.

Implementing timeout function with thread:

In order to implement the timeout function, we need one thread to execute the function and another to watch the time that it takes. When the time is over only the second thread knows it. If we could simply kill the function thread everything would work as expected but since they share the same execution context, we can’t. Threads can’t be killed so what we can do is to signal the other thread that it should stop. The drawback of this approach is that it can’t be used in all the cases. For example if we are using an external library inside that function, the execution might be stuck in a code that we don’t have access to. In this case we can’t guarantee that the function will stop exactly after the given period. But in most of the cases this approach is enough. In the first thread (the one that executes the function) we have to make regular checks if the time is over. We can use the Event object from the threading module in Python 3 to send a signal from one thread to another. Here is an example:

Источник