Fix run out of heap on ESP32

[nikito7]

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Heltec (Lora32) V3
  • LilyGo T-Deck
  • LilyGo T-Beam
  • RAK WisBlock 4631
  • Seeed Studio T-1000E tracker card
  • Other (please specify below)

ESP32 devices.

[CLAassistant]

All committers have signed the CLA.

[fifieldt]

Hi @nikito7 , thanks for your patch :)

Would you be able to tell us more about the background? What situation did you run out of heap? Also, is there any impact on other uses of the memory by making this change?

[nikito7]

It may only be used here:

// returns true if the maximum number of nodes is reached or we are running low on memory
bool NodeDB::isFull()
{
    return (numMeshNodes >= MAX_NUM_NODES) || (memGet.getFreeHeap() < MINIMUM_SAFE_FREE_HEAP);
}

firmware/src/mesh/NodeDB.cpp

Line 1638 in 066609a

return (numMeshNodes >= MAX_NUM_NODES) || (memGet.getFreeHeap() < MINIMUM_SAFE_FREE_HEAP);

If 1500 default it's all free heap, it's bad.
ESP32 below 15kb could crash.

This it's only for nodes. I don't know if impact anywhere.

Because my true solution for my problem was:

  -D MESHTASTIC_EXCLUDE_BLUETOOTH=1
  -D MESHTASTIC_EXCLUDE_AUDIO=1
  -D MESHTASTIC_EXCLUDE_PAXCOUNTER=1
  -D MESHTASTIC_EXCLUDE_RANGETEST=1
  -D MESHTASTIC_EXCLUDE_ATAK=1
  -D MINIMUM_SAFE_FREE_HEAP=25000

My current it's about 90kB now.
With default firmware it's always below 20kB.
And wifi hangs or esp32 reboot.

[nikito7]

Main problem it's Bluetooth.
But this 'MINIMUM_SAFE_FREE_HEAP' should the used more in code.

I only found it in Nodes.

Heap fragmentation could be a issue too.

---

After update to BLE version:

• ping OK
• RF OK
• API down
• Atfer 10min, API ok

[mverch67]

I don't think the proposed solution is reasonable. Instead of changing the global value (which is also used for e.g. nrf devices that do not have much memory) you can limit the use to specific devices in the platformio.ini files (see also arch folder).
Also, this value has been used for months or even years without any major problems and now you suggest the ten-fold value which seems quite exaggerated. Did you try other values like 2000 or 2500, 3000, and so on?

[nikito7]

This PR it's mainly a proof of concept.
If you don't agree, it's ok.
I don't have the perfect solution.
The main problem it's Bluetooth itself.

If someone have issues, adapt this for your needs:

[han32opt]
build_flags =
  -D PRIVATE_HW
  -D DEFAULT_REBOOT_SECONDS=3
  -D MESHTASTIC_EXCLUDE_PAXCOUNTER=1
  -D MESHTASTIC_EXCLUDE_RANGETEST=1
  -D MESHTASTIC_EXCLUDE_ATAK=1
  -D MESHTASTIC_EXCLUDE_STOREFORWARD=1

[env:han32gw-no-ble]
extends = esp32_base
board = esp32dev
board_check = true
build_flags = 
  ${esp32_base.build_flags}
  ${han32opt.build_flags}
  -I ../variants/han32gw
  -D MESHTASTIC_EXCLUDE_BLUETOOTH=1
  -D MINIMUM_SAFE_FREE_HEAP=25000
  -D MAX_NUM_NODES=100
upload_speed = 460800

[env:han32gw-ble]
extends = esp32_base
board = esp32dev
board_check = true
build_flags = 
  ${esp32_base.build_flags}
  ${han32opt.build_flags}
  -I ../variants/han32gw
  -D MESHTASTIC_EXCLUDE_BLUETOOTH=0
  -D HAS_BLUETOOTH=1
  -D MINIMUM_SAFE_FREE_HEAP=15000
  -D MAX_NUM_NODES=100
upload_speed = 460800

; EOF

[nikito7]

A last comment. My ble firmware stills hangs wifi connection after a while. I need to reboot Acess Point.

Without BLE stack it's perfect.