Arduino-esp32: WiFi.h WiFiClient instance cause ESP32 to freeze randomly

Created on 30 Nov 2018 · 10Comments · Source: espressif/arduino-esp32

Hardware:

Board: ESP32 Dev Module
Core Installation/update date: ?11/jul/2017?
IDE name: Arduino IDE
Flash Frequency: ?40Mhz?
PSRAM enabled: no
Upload Speed: 115200
Computer OS: Windows 8.1

Description:

I am using the example provided with the ESP32 SDK about WiFiServer to send constantly data to a client.
Anyway in a few hundreds of lops the loop() just freeze for indefinitely long ( usually at least 2 seconds, up to like 11 seconds ), doing nothing, nothing else happens in the main loop during the freeze.
I have put a delay(100);, but still the issue is reprocuting on all ESP32 boards I have.
Every 100-500 loops it freeze for at least 2 seconds up to 11 seconds.

Sketch:

//Change the code below by your sketch
#include <Arduino.h>
#include <WiFi.h>

WiFiServer * wifiServer;

WiFiClient * clientX;

unsigned long rBuffer[ 65 ];

void setup() 
{
       Serial.begin( 115200 );
       wifiServer = new WiFiServer( 20800 );

    WiFi.onEvent( WiFiEvent );

    WiFi.mode( WIFI_AP );

    WiFi.softAP( "lVision" );

    wifiServer->begin();
    serverX = IPAddress( 192, 168, 100, 2 );
    clientX = new WiFiClient();
}

void loop()
 {
        rBuffer[ 64 ] = (unsigned long )'d'; // this is data

    if( clientX->connect( serverX, 20800 ) )
    {
        if( clientX->connected()  )
        {
            Serial.println( millis() );
            clientX->write( ( const uint8_t* )rBuffer, sizeof( rBuffer ) );

            clientX->stop();
            clientX->flush();
        }
    }
}

void WiFiEvent( WiFiEvent_t event )
{
    switch( event )
    {
        case SYSTEM_EVENT_AP_START:
        {
            IPAddress ipA = IPAddress( 192, 168, 100, 1 );
            IPAddress ipS = IPAddress( 255, 255, 255, 0 );
            WiFi.softAPConfig( ipA, ipA, ipS );
        }
        break;

        default:
        break;
    }
}

Debug Messages:

Source

YordanYanakiev

All 10 comments

Also I 've report some esp32 freeze when I check Wifi status or some network operations, udp reply or mysql query

asetyde on 30 Nov 2018

I don't check neither the wifi status, nor i do network operations, nor database stuff.
I got nothing attached to the board.
Actually I do nothing into the mail loop. Just sending some random data, and yet - it stucking randomly.

YordanYanakiev on 30 Nov 2018

I also use OTA , random data is sent sometimes

asetyde on 30 Nov 2018

I am not sure I do understand.

YordanYanakiev on 1 Dec 2018

me-no-dev has done some work on the WiFi queue since the 1.0.0 release. Can you test with the pre-release version and see if it is better? Also, don't close the session if it is not necessary. There's a fair amount of overhead establishing a TCP session.

lbernstone on 1 Dec 2018

❤1

It worked !!!!! Now it does not fails the loop() !
The process keeps going without any drop already 30 minutes.
Previously there were 1 significant loop failure each 30-60 seconds or so, now it seems the problem to be gone.
Anyway at some point there is a small performance drop about 1 per a few minutes or so, but it is insignificant.
anyway.

Great work !

YordanYanakiev on 2 Dec 2018

O well.. I just have posted this and it failed the main loop for about 8 seconds again. :D
Anyway it is at least very rare now.

YordanYanakiev on 2 Dec 2018

Add some delay on loop() is really necessary : ESP32 is powerful, and running at 320Mhz, so without any delay it will do the same operation may hundreds or thousands times per second, and this can cause instabilities

Additionally: what about keep the connection open with server instead open and close every loop() ? this will save you a lot of time and resources and reduce if not solve these instabilities