Task in V3.x require 2 to 3 times larger stack than V2.0.17

[plrfishing]

Board

ESP32 Dev board and ESP-S2 mini

Device Description

Dev board and S2 mini both exhibit same behavior

Hardware Configuration

same behavior if pins are used or not used

Version

v3.2.0

IDE Name

VSCode with platformio

Operating System

Windows11

Flash frequency

40MHz

PSRAM enabled

yes

Upload speed

921600 but other speeds same issue

Description

Had code for version 2.0.17 which worked with multiple tasks given stack sizes of 4000. Updated to V3.2.0 and no code changes and freeheap would drop quickly after 2-3 iterations so low as to cause system resets. Increased stack sizes to 10,000 and freeheap remains at 7000 to 8000. This is not causing a specific issue for me since the additional stack allocations are not an issue with this code size.

So does v3.x require larger stack size than V.2.0.17?

Sketch

Not provided

Debug Message

Guru Meditation Error: Core 1 panic'ed (LoadProhibited). Exception was unhandled. I did add code to delete the task if freeheap dropped below 1000 and restart the task. However the larger initial stack size of 10000 seems to work for V3.x.

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[SuGlider]

Guru Meditation Error: Core 1 panic'ed (LoadProhibited).

This may not be necessarily related to stack size. It happens when HEAP is low and a malloc() fails returning NULL to a pointer, which is not tested and used.
Or when a pointer is used, but it points to some random address out of memory space.

https://docs.espressif.com/projects/esp-idf/en/v3.3.5/api-guides/fatal-errors.html#loadprohibited-storeprohibited

[SuGlider]

So does v3.x require larger stack size than V.2.0.17?

Stack is used within a Task. For that the answer is no, there is no larger requirement.
Stack size is tie to the Task demand of memory allocated within that Task, such as local variable declaration or arrays that are declared in the Task code.

Does v3.x use more HEAP memory than V2.x, yes. An empty sketch will leave a bit less HEAP left in 3.x ~~ about 10K or 20K less. Some Libraries may consume more memory than in V2.x, mostly WiFi.

Task Stack memory is taken from HEAP left memory space.
Many tasks that require a lot of Stack space will consume HEAP to allocate a block of memory for each Stack block of each Task.

https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/mem_alloc.html
https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-guides/performance/ram-usage.html

[SuGlider]

freeheap would drop quickly after 2-3 iterations so low as to cause system resets

No idea what code is run in the task, but Stack and Heap are different memory spaces.
Task Stack is allocated by local task variable declared in the code.
malloc() will allocate memory from heap, not from the task stack.

void Task1(void *pvParameters) {
  int matrix[10][10];  // statically allocated on the stack
  // ...
  // no need to free matrix - when the task is destoyed, its stack block of memory is released autoamtically
}

void Task2(void *pvParameters) {
  int **matrix = (int **)malloc(sizeof(int*) * rows); // using malloc or new
  // ...
  // latter manually free it
}

Key Differences Between Stack and Heap

Feature	Stack	Heap
Lifetime	Tied to function/task scope	Persists until manually freed
Size	Limited (per-task stack size)	Larger (based on available RAM)
Speed	Fast (allocated automatically)	Slower (requires dynamic allocation)
Management	Automatic	Manual (allocate and free yourself)

[SuGlider]

Closing this issue. Feel free to open it again.