Welcome to Circuit BreakerΒΆ
The circuit breaker package contains a decorator that you can apply to your Python function, which will prevent it from running longer than a specified timeout. If the timeout is reached, a “backup function” is run immediately and its value is returned.
I wrote this decorator in order to guarantee that a microservice never takes too long to return a result, avoiding degradation of downstream services.
To install it, just use pip:
pip install circuit_breaker
To use it, decorate your function in the normal way, providing two
keyword arguments: timeout and timeout_function. Here is an
example of a function that takes longer than one second to run half
of the times it’s called. When one second has elapsed, a backup function
is called immediately.
def backup_function(x):
return 'I am in the backup function'
@circuit_breaker(timeout=1, timeout_function=backup_function)
def slow_function(x):
time.sleep(2 * random.random())
return 'the function finished in time: ' + str(x)
A potential “gotcha” when using this decorator is that because
decorators are always applied at compile time, the function
you use as your backup_function must be defined before
the decorated function. In other words, if we were to move
the backup_function in the example to a position after
slow_function, we’d get a compile-time error, which would
make us sad.
Contact zac.ernst@gmail.com with questions/comments/concerns/threats.