Heap memory leak caused by client.connect() ?

[robert-rudolph]

I call the following function periodically on an ESP32. The free heap decreases each time I call connectToMQTT(), indicating a memory leak.

If I comment out the line containing mqtt_client.connect(), then the memory leak goes away, and I have perfect heap preservation.

I've dug through the library source here and not found any unmatched malloc() calls, so I'm stumped as to where the memory is going. Any help would be appreciated!

void connectToMQTT()
{
  int retries = 0;
  int success = false;
  while ( !success && retries < 10) {
    // mqtt_client.disconnect();
    success = mqtt_client.connect("0031");
    delay(100);
    retries++;
  }
}

[256dpi]

Do you know by how much the heap increases on every call?

[robert-rudolph]

I'm loosing between 108 and 836 bytes of heap per call.

this may be a problem with the WiFiClient library for ESP32, and not this library.
Seems some similar leak was present on ESP8266 with PubSubClient library on reconnects:

esp8266/Arduino#4497

esp8266/Arduino#7059

[robert-rudolph]

Closing, this seems to be a leak in the WiFiClient or WiFiClientSecure libraries within ESP32-Arduino Core. Thank you.

[dmarc1234]

I am experiencing the same issue with a failed mqtt_client.connect() on the ESP32, losing between 4700~5000 bytes of heap on each call.

Was this problem ever tracked down ?

[robert-rudolph]

I traced this to the WifiClient core, it is not an issue in the ardino-mqtt repo.

See this thread for a temp fix: espressif/arduino-esp32#3808 (comment)