Threading and Multiprocessing#
New in version 0.13.0.
Threading#
While xlwings is not technically thread safe, it’s still easy to use it in threads as long as you have at least v0.13.0 and stick to a simple rule: Do not pass xlwings objects to threads. This rule isn’t a requirement on macOS, but it’s still recommended if you want your programs to be cross-platform.
Consider the following example that will NOT work:
import threading
from queue import Queue
import xlwings as xw
num_threads = 4
def write_to_workbook():
while True:
myrange = q.get()
myrange.value = myrange.address
print(myrange.address)
q.task_done()
q = Queue()
for i in range(num_threads):
t = threading.Thread(target=write_to_workbook)
t.daemon = True
t.start()
for cell in ['A1', 'A2', 'A3', 'A4', 'A5', 'A6', 'A7', 'A8', 'A9', 'A10']:
# THIS DOESN'T WORK - passing xlwings objects to threads will fail!
myrange = xw.Book('Book1.xlsx').sheets[0].range(cell)
q.put(myrange)
q.join()
To make it work, you simply have to fully qualify the cell reference in the thread instead of passing a Book
object:
import threading
from queue import Queue
import xlwings as xw
num_threads = 4
def write_to_workbook():
while True:
cell_ = q.get()
xw.Book('Book1.xlsx').sheets[0].range(cell_).value = cell_
print(cell_)
q.task_done()
q = Queue()
for i in range(num_threads):
t = threading.Thread(target=write_to_workbook)
t.daemon = True
t.start()
for cell in ['A1', 'A2', 'A3', 'A4', 'A5', 'A6', 'A7', 'A8', 'A9', 'A10']:
q.put(cell)
q.join()
Multiprocessing#
Note
Multiprocessing is only supported on Windows!
The same rules apply to multiprocessing as for threading, here’s a working example:
from multiprocessing import Pool
import xlwings as xw
def write_to_workbook(cell):
xw.Book('Book1.xlsx').sheets[0].range(cell).value = cell
print(cell)
if __name__ == '__main__':
with Pool(4) as p:
p.map(write_to_workbook,
['A1', 'A2', 'A3', 'A4', 'A5', 'A6', 'A7', 'A8', 'A9', 'A10'])