Getting error OSError("can't create thread",) when try to create a thread inside a thread

[amplatzer]

Micropython 1.20
Module, ESP32-pico-d4

So my code is like

import _thread
def func_a():
    print('func a called')
    
def func_b():
    print('func b called')
    _thread.start_new_thread(func_a,[])
    
_thread.start_new_thread(func_b,[])

for the past few weeks, it has worked fine, but today, I found that the second thread except with ERROR OSError("can't create thread",) .

What should I do for root cause finding. Can it be something related to memory?
I did increase the size of the .py file in the past few days though.

[jimmo]

This error is being returned from the IDF's xTaskCreatePinnedToCore function. Perhaps it cannot allocate the stack.

What sort of things have changed in your program since it worekd?

Have you tried in v1.21.0 or v1.22.0-preview?

[amplatzer]

What sort of things have changed in your program since it worekd?
—— No really, just increase the size of an unrelieved dictionary.

Have you tried in v1.21.0 or v1.22.0-preview?
—— No, I was starting this project with v1.21.0, but for some reason, the kernel always crashes when the code try to turn off and on the BLE.

[amplatzer]

I do find out, the ERROR always comes out when 2 threads try to do ble.gatts_notify at the same time. But it doesn't happen every time. So that confuses me.

[nestorld]

I'm getting that error (OSError: can't create thread) on a Lilygo T-Beam ESP32 board with Micropython 1.21 (also tried with 1.22). I have several custom libraries running on it for gps, ble and mqtt. All of them use threads and work well when I test them separately, but when I activate all these libraries together I start getting this error. I would say that it is because of scarce resources (mainly memory), but this board has 8 MB of SPIRAM, and it should be more than enough (even with 4 MB as I understand it is the max that ESP32 can use). I have built a custom firmware including these libraries on it to see if that helps, but still getting the same error. I did use this command to build the firmware:

make BOARD=ESP32_GENERIC BOARD_VARIANT=SPIRAM FROZEN_MANIFEST="" FROZEN_MPY_DIR=$UPYDIR/modules

Something I'm not sure about is if the code is really making use of the SPIRAM. I have used micropython.mem_info() in the Thonny's REPL console and got this:

stack: 736 out of 15360
GC: total: 64000, used: 15824, free: 48176, max new split: 4063232
No. of 1-blocks: 356, 2-blocks: 81, max blk sz: 32, max free sz: 2999

Am I missing something to give enough resources to my code to use these threads?
Thanks in advance for any help on this!

[amplatzer]

import _thread
from micropython import mem_info
from gc import mem_free,collect
import time

def test():
    time.sleep(30)
    
try:
    for i in range(30):
        print(i)
        _thread.start_new_thread(test,[])
        time.sleep(0.5)
except:
    print('MEM_FREE: ',mem_free())
    print('########')
    print(mem_info())

IMicroPython v1.20.0-dirty on 2023-11-07; ESP32 module with ESP32
Type "help()" for more information.
%run -c $EDITOR_CONTENT
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
MEM_FREE: 98992
########
stack: 720 out of 15360
GC: total: 108032, used: 9040, free: 98992
No. of 1-blocks: 187, 2-blocks: 51, max blk sz: 32, max free sz: 6187
None

I'm using esp32-pico-d4, looks like there is a limitation on thread? when it comes to my code, I can only create 2 threads, and getting error with the 3rd one. But what can we learn from the memery info ?\

[amplatzer]

maybe you can try _thread.stack_size(4096) at the begging of your code.