How to realize a RW lock with multithreading gRPC?

I am trying to write a simple multi-threading server-client stock trading Python program with gRPC and concurrent.future.ThreadPoolExecutor

The server will run a specific number of threads, performs Lookup() and Trade() request sent from clients. The server will maintain a list. That means Lookup() should set read lock, and Trade() should set write lock.

However, it seems that the documentation of gRPC doesn't mention anything about RW lock. Is ThreadPoolExecutor thred-safe?

Any suggestion is appreciated!

Solution

A threadPoolExecutor with a max_workers greater than 1 requires that your only submit functions that reference thread-safe shared state only. For instance, you should not mutate a global variable from multiple jobs submitted to the thread pool, thus you must protect this with some kind of synchronization primitive.

# /!\ Not thread-safe

from concurrent.futures import ThreadPoolExecutor


def mutate_value():
  global some_value
  some_value += 1


some_value = 0

with ThreadPoolExecutor(max_workers=2) as e:
  e.submit(mutate_value)
  e.submit(mutate_value)

# Thread-safe

from concurrent.futures import ThreadPoolExecutor
from threading import Lock


lock = Lock()


def mutate_value():
  global some_value

  with lock:
    some_value += 1


some_value = 0

with ThreadPoolExecutor(max_workers=2) as e:
  e.submit(mutate_value)
  e.submit(mutate_value)