Python3: Shared Array with strings between processes

Question

I want to share a list with strings between processes, but unfortunately I receive the error message "ValueError: character U+169ea10 is not in range [U+0000; U+10ffff]".

Here is the Python 3 code:

from multiprocessing import Process, Array, Lock
from ctypes import c_wchar_p
import time
def run_child(a):
 time.sleep(2)
 print(a[0]) # print foo
 print(a[1]) # print bar
 print(a[2]) # print baz
 print("SET foofoo barbar bazbaz")
 a[0] = "foofoo"
 a[1] = "barbar"
 a[2] = "bazbaz"
lock = Lock()
a = Array(c_wchar_p, range(3), lock=lock)
p = Process(target=run_child, args=(a,))
p.start()
print("SET foo bar baz")
a[0] = "foo"
a[1] = "bar"
a[2] = "baz"
time.sleep(4)
print(a[0]) # print foofoo
print(a[1]) # print barbar
print(a[2]) # print bazbaz

Does someone knows what I am doing wrong?

Regards Jonny

• Paulo Scardine: You mast use bytes instead of strings if you are dealing with ctypes.

Answer 1

Your ctype doesn't match the content of your Array. Your initializing data should be a list of strings to match the ctype you're specifying. You're initializing it with range(3), which evaluates to integers, not strings.

Should be more like

a = Array(c_wchar_p, ('', '', ''), lock=lock)

From the docs

c_wchar_p

Represents the C wchar_t * datatype, which must be a pointer to a zero-terminated wide character string. The constructor accepts an integer address, or a string.

• Jonny: Thank you very much for your hint!