Threading issue - socket is already closed

[mmvds]

I've tried to use Threading to increase an execution speed
simple example - get hashes for blocks in range(11704730, 11704741)
I wrote the following:

import threading
import concurrent.futures
from substrateinterface import SubstrateInterface

blocks = list(range(11704730, 11704741))

kusama_substrate = SubstrateInterface(url= 'wss://kusama-rpc.polkadot.io/', ss58_format=2)

def hash_block(current_block):
    try:
        block_info = kusama_substrate.get_block(block_number=current_block)
        if block_info:     
            print(current_block, block_info['header']['hash'])
        else:
            print(current_block, "no hash")
    except Exception as e:
        print(e)

with concurrent.futures.ThreadPoolExecutor(4) as executor:
    executor.map(hash_block, blocks)

when I run, it works well for several blocks and after that I get "socket is already closed" error

11704733 0x00721eb05b33a6684afbbc0aae101be3e8cb1e5648a7dae780a998fca9633ea2
11704731 0xcbbb4561a26e9b3f74231b1efd26af3b1ee5155f05c6d2674d2245e28994ac44
11704732 0x132e43ca3a154e102de53877784237f3528f3bee1082a7e20aeccd330dbf77c5
11704730 0x001de1a436000e1b537141ac8b05390bfcd8df76cbf899910f03d95ebefe9814
11704734 0xf0939ca7baf0483d338a1a139c5d89905fcdf47fecac502710d0bea52306375e
11704735 0x1fd6b1a03cc066c353df3379db32469f5ba75d1cdbeaf704eea0b2d9128c0b4e
11704736 0x630ab2618541c7cc3f7bc55b0e691d1514de0d654670c30c262b2cade0ae67ed
11704737 0xeeb47a564f9f0c7ae09a411ab751ba45051a4646b110ef97efeeafebc1d1a6f0
Connection to remote host was lost.
socket is already closed.
socket is already closed.

so, we lost several blocks
is there any way how to avoid this issue?

[arjanz]

I tested your script with a local node endpoint and experienced no connection problems, so I guess it is a (probably intended) throttling limitation of the public endpoints..

I guess the best solution is to host your own nodes, as you will probably improve performance significantly even without using threads.

[mmvds]

ok, thank you very much! will check it