I've a function that runs multiple queries in parallel but I'm having some troubles to run my function using multprocessing with more than argument. I've this code:
def run(args):
query, cursor = args
cursor.execute(query)
with multiprocessing.Pool(processes=10) as pool:
args = (product(queries),cursor)
results = pool.starmap(run(args))
If I run only pool.starmap(run(product(queries)))
it works well, however I have the need to pass also the cursor object.
How I can do that?
I'm having the following error:
TypeError: starmap() missing 1 required positional argument: 'iterable'
There are some problems with your code:
run
with parameters, then pass the result to starmap
, but you have to pass both the function and its parameters separately to starmap
map
; for starmap
it should be def run(query, cursor)
Try this:
import multiprocessing
import itertools
def run(args):
query, cursor = args
print("running", query, cursor)
queries = ["foo", "bar", "blub"]
cursor = "whatever"
with multiprocessing.Pool(processes=10) as pool:
args = ((args, cursor) for args in itertools.product(queries))
results = pool.map(run, args)
There may be more "upstream" errors, like that SSLSocket
stuff, but this should at least (try to) call the function with the correct parameters.