delay() 指令在带有 ESPAsyncWebServer 库的 ESP8266 / nodeMCU 上生成异常 (9) 错误

Question

The following script generates an exception 9 error and resets the nodeNUC. The conflicting line is the one that says "delay(1)". If I comment it out it works.

Is it possible to delay the execution without getting an exception error?

SCRIPT

#include <ESP8266WiFi.h>
#include <Hash.h>
#include <ESPAsyncTCP.h>
#include <ESPAsyncWebServer.h>

AsyncWebServer server(80);

const char* ssid = "SSID";
const char* password = "PASS";
int x=0;

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  Serial.print("\n");
  WiFi.begin(ssid, password);
  if (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.printf("\nWiFi Failed!\n");
    return;
  }
  Serial.print("\nHTTP://");
  Serial.println(WiFi.localIP());

  server.on("/", HTTP_GET, [](AsyncWebServerRequest * request) {
    
    delay(1);   // --- THIS IS THE CONFLICTING INSTRUCTION
    
    String reply=(String)millis();
    request->send(200, "text/plain", (String)millis()+" - "+(String)x++);
  });

  server.onNotFound(notFound);
  server.begin();
}

void loop() {
  delay(1000);
  digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
}

void notFound(AsyncWebServerRequest *request) {
  request->send(404, "text/plain", "404 Not found");
}

ERROR

--------------- CUT HERE FOR EXCEPTION DECODER ---------------

Exception (9): epc1=0x40105b5d epc2=0x00000000 epc3=0x00000000 excvaddr=0xffffffff depc=0x00000000

stack>>>

ctx: sys sp: 3fffed70 end: 3fffffb0 offset: 0190 3fffef00: 000000cc 00000000 3ffefe50 402106d0
3fffef10: 402352c8 00000001 00000000 402388fd
3fffef20: 40235bd7 00000042 00000000 40235b40
3fffef30: 3ffecbd0 40235462 3fffdab0 00000000
3fffef40: 3fffdcc0 3ffe9518 00000001 00000001
3fffef50: 3ffe9518 40000f49 3fffdab0 40000f49
3fffef60: 40000e19 00048249 00000000 00000005
3fffef70: 3fffefc0 aa55aa55 000000ed 4010540d
3fffef80: 40105413 00000000 00000005 40100a5c
3fffef90: 4010000d 07070605 00048249 401000ac
3fffefa0: 4022a540 3fffef3c 4022a4f9 3fffff68
3fffefb0: 3fffffc0 00000000 00000000 feefeffe
3fffefc0: feefeffe feefeffe feefeffe feefeffe
3fffefd0: feefeffe feefeffe feefeffe feefeffe
3fffefe0: feefeffe feefeffe feefeffe feefeffe
3fffeff0: feefeffe feefeffe feefeffe feefeffe
3ffff000: feefeffe feefeffe feefeffe feefeffe
3ffff010: feefeffe feefeffe feefeffe feefeffe
3ffff020: feefeffe feefeffe feefeffe feefeffe
3ffff030: feefeffe feefeffe feefeffe feefeffe
3ffff040: feefeffe feefeffe feefeffe feefeffe
3ffff050: feefeffe feefeffe feefeffe feefeffe
3ffff060: feefeffe feefeffe feefeffe feefeffe
3ffff070: feefeffe feefeffe feefeffe feefeffe
3ffff080: feefeffe feefeffe feefeffe feefeffe
3ffff090: feefeffe feefeffe feefeffe feefeffe
3ffff0a0: feefeffe feefeffe feefeffe feefeffe
3ffff0b0: feefeffe feefeffe feefeffe feefeffe
3ffff0c0: feefeffe feefeffe feefeffe feefeffe
3ffff0d0: feefeffe feefeffe feefeffe feefeffe
3ffff0e0: feefeffe feefeffe feefeffe feefeffe
3ffff0f0: feefeffe feefeffe feefeffe feefeffe
3ffff100: feefeffe feefeffe feefeffe feefeffe
3ffff110: feefeffe feefeffe feefeffe feefeffe
3ffff120: feefeffe feefeffe feefeffe feefeffe
3ffff130: feefeffe feefeffe feefeffe feefeffe
3ffff140: feefeffe feefeffe feefeffe feefeffe
3ffff150: feefeffe feefeffe feefeffe feefeffe
3ffff160: feefeffe feefeffe feefeffe feefeffe
3ffff170: feefeffe feefeffe feefeffe feefeffe
3ffff180: feefeffe feefeffe feefeffe feefeffe
3ffff190: feefeffe feefeffe feefeffe feefeffe
3ffff1a0: feefeffe feefeffe feefeffe feefeffe
3ffff1b0: feefeffe feefeffe feefeffe feefeffe
3ffff1c0: feefeffe feefeffe feefeffe feefeffe
3ffff1d0: feefeffe feefeffe feefeffe feefeffe
3ffff1e0: feefeffe feefeffe feefeffe feefeffe
3ffff1f0: feefeffe feefeffe feefeffe feefeffe
3ffff200: feefeffe feefeffe feefeffe feefeffe
3ffff210: feefeffe feefeffe feefeffe feefeffe
3ffff220: feefeffe feefeffe feefeffe feefeffe
3ffff230: feefeffe feefeffe feefeffe feefeffe
3ffff240: feefeffe feefeffe feefeffe feefeffe
3ffff250: feefeffe feefeffe feefeffe feefeffe
3ffff260: feefeffe feefeffe feefeffe feefeffe
3ffff270: feefeffe feefeffe feefeffe feefeffe
3ffff280: feefeffe feefeffe feefeffe feefeffe
3ffff290: feefeffe feefeffe feefeffe feefeffe
3ffff2a0: feefeffe feefeffe feefeffe feefeffe
3ffff2b0: feefeffe feefeffe feefeffe feefeffe
3ffff2c0: feefeffe feefeffe feefeffe feefeffe
3ffff2d0: feefeffe feefeffe feefeffe feefeffe
3ffff2e0: feefeffe feefeffe feefeffe feefeffe
3ffff2f0: feefeffe feefeffe feefeffe feefeffe
3ffff300: feefeffe feefeffe feefeffe feefeffe
3ffff310: feefeffe feefeffe feefeffe feefeffe
3ffff320: feefeffe feefeffe feefeffe feefeffe
3ffff330: feefeffe feefeffe feefeffe feefeffe
3ffff340: feefeffe feefeffe feefeffe feefeffe
3ffff350: feefeffe feefeffe feefeffe feefeffe
3ffff360: feefeffe feefeffe feefeffe feefeffe
3ffff370: feefeffe feefeffe feefeffe feefeffe
3ffff380: feefeffe feefeffe feefeffe feefeffe
3ffff390: feefeffe feefeffe feefeffe feefeffe
3ffff3a0: feefeffe feefeffe feefeffe feefeffe
3ffff3b0: feefeffe feefeffe feefeffe feefeffe
3ffff3c0: feefeffe feefeffe feefeffe feefeffe
3ffff3d0: feefeffe feefeffe feefeffe feefeffe
3ffff3e0: feefeffe feefeffe feefeffe feefeffe
3ffff3f0: feefeffe feefeffe feefeffe feefeffe
3ffff400: feefeffe feefeffe feefeffe feefeffe
3ffff410: feefeffe feefeffe feefeffe feefeffe
3ffff420: feefeffe feefeffe feefeffe feefeffe
3ffff430: feefeffe feefeffe feefeffe feefeffe
3ffff440: feefeffe feefeffe feefeffe feefeffe
3ffff450: feefeffe feefeffe feefeffe feefeffe
3ffff460: feefeffe feefeffe feefeffe feefeffe
3ffff470: feefeffe feefeffe feefeffe feefeffe
3ffff480: feefeffe feefeffe feefeffe feefeffe
3ffff490: feefeffe feefeffe feefeffe feefeffe
3ffff4a0: feefeffe feefeffe feefeffe feefeffe
3ffff4b0: feefeffe feefeffe feefeffe feefeffe
3ffff4c0: feefeffe feefeffe feefeffe feefeffe
3ffff4d0: feefeffe feefeffe feefeffe feefeffe
3ffff4e0: feefeffe feefeffe feefeffe feefeffe
3ffff4f0: feefeffe feefeffe feefeffe feefeffe
3ffff500: feefeffe feefeffe feefeffe feefeffe
3ffff510: feefeffe feefeffe feefeffe feefeffe
3ffff520: feefeffe feefeffe feefeffe feefeffe
3ffff530: feefeffe feefeffe feefeffe feefeffe
3ffff540: feefeffe feefeffe feefeffe feefeffe
3ffff550: feefeffe feefeffe feefeffe feefeffe
3ffff560: feefeffe feefeffe feefeffe feefeffe
3ffff570: feefeffe feefeffe feefeffe feefeffe
3ffff580: feefeffe feefeffe feefeffe feefeffe
3ffff590: feefeffe feefeffe feefeffe feefeffe
3ffff5a0: feefeffe feefeffe feefeffe feefeffe
3ffff5b0: feefeffe feefeffe feefeffe feefeffe
3ffff5c0: feefeffe feefeffe feefeffe feefeffe
3ffff5d0: feefeffe feefeffe feefeffe feefeffe
3ffff5e0: feefeffe feefeffe feefeffe feefeffe
3ffff5f0: feefeffe feefeffe feefeffe feefeffe
3ffff600: feefeffe feefeffe feefeffe feefeffe
3ffff610: feefeffe feefeffe feefeffe feefeffe
3ffff620: feefeffe feefeffe feefeffe feefeffe
3ffff630: feefeffe feefeffe feefeffe feefeffe
3ffff640: feefeffe feefeffe feefeffe feefeffe
3ffff650: feefeffe feefeffe feefeffe feefeffe
3ffff660: feefeffe feefeffe feefeffe feefeffe
3ffff670: feefeffe feefeffe feefeffe feefeffe
3ffff680: feefeffe feefeffe feefeffe feefeffe
3ffff690: feefeffe feefeffe feefeffe feefeffe
3ffff6a0: feefeffe feefeffe feefeffe feefeffe
3ffff6b0: feefeffe feefeffe feefeffe feefeffe
3ffff6c0: feefeffe feefeffe feefeffe feefeffe
3ffff6d0: feefeffe feefeffe feefeffe feefeffe
3ffff6e0: feefeffe feefeffe feefeffe feefeffe
3ffff6f0: feefeffe feefeffe feefeffe feefeffe
3ffff700: feefeffe feefeffe feefeffe feefeffe
3ffff710: feefeffe feefeffe feefeffe feefeffe
3ffff720: feefeffe feefeffe feefeffe feefeffe
3ffff730: feefeffe feefeffe feefeffe feefeffe
3ffff740: feefeffe feefeffe feefeffe feefeffe
3ffff750: feefeffe feefeffe feefeffe feefeffe
3ffff760: feefeffe feefeffe feefeffe feefeffe
3ffff770: feefeffe feefeffe feefeffe feefeffe
3ffff780: feefeffe feefeffe feefeffe feefeffe
3ffff790: feefeffe feefeffe feefeffe feefeffe
3ffff7a0: feefeffe feefeffe feefeffe feefeffe
3ffff7b0: feefeffe feefeffe feefeffe feefeffe
3ffff7c0: feefeffe feefeffe feefeffe feefeffe
3ffff7d0: feefeffe feefeffe feefeffe feefeffe
3ffff7e0: feefeffe feefeffe feefeffe feefeffe
3ffff7f0: feefeffe feefeffe feefeffe feefeffe
3ffff800: feefeffe feefeffe feefeffe feefeffe
3ffff810: feefeffe feefeffe feefeffe feefeffe
3ffff820: feefeffe feefeffe feefeffe feefeffe
3ffff830: feefeffe feefeffe feefeffe feefeffe
3ffff840: feefeffe feefeffe feefeffe feefeffe
3ffff850: feefeffe feefeffe feefeffe feefeffe
3ffff860: feefeffe feefeffe feefeffe feefeffe
3ffff870: feefeffe feefeffe feefeffe feefeffe
3ffff880: feefeffe feefeffe feefeffe feefeffe
3ffff890: feefeffe feefeffe feefeffe feefeffe
3ffff8a0: feefeffe feefeffe feefeffe feefeffe
3ffff8b0: feefeffe feefeffe feefeffe feefeffe
3ffff8c0: feefeffe feefeffe feefeffe feefeffe
3ffff8d0: feefeffe feefeffe feefeffe feefeffe
3ffff8e0: feefeffe feefeffe feefeffe feefeffe
3ffff8f0: feefeffe feefeffe feefeffe feefeffe
3ffff900: feefeffe feefeffe feefeffe feefeffe
3ffff910: feefeffe feefeffe feefeffe feefeffe
3ffff920: feefeffe feefeffe feefeffe feefeffe
3ffff930: feefeffe feefeffe feefeffe feefeffe
3ffff940: feefeffe feefeffe feefeffe feefeffe
3ffff950: feefeffe feefeffe feefeffe feefeffe
3ffff960: feefeffe feefeffe feefeffe feefeffe
3ffff970: feefeffe feefeffe feefeffe feefeffe
3ffff980: feefeffe feefeffe feefeffe feefeffe
3ffff990: feefeffe feefeffe feefeffe feefeffe
3ffff9a0: feefeffe feefeffe feefeffe feefeffe
3ffff9b0: feefeffe feefeffe feefeffe feefeffe
3ffff9c0: feefeffe feefeffe feefeffe feefeffe
3ffff9d0: feefeffe feefeffe feefeffe feefeffe
3ffff9e0: feefeffe feefeffe feefeffe feefeffe
3ffff9f0: feefeffe feefeffe feefeffe feefeffe
3ffffa00: feefeffe feefeffe feefeffe feefeffe
3ffffa10: feefeffe feefeffe feefeffe feefeffe
3ffffa20: feefeffe feefeffe feefeffe feefeffe
3ffffa30: feefeffe feefeffe feefeffe feefeffe
3ffffa40: feefeffe feefeffe feefeffe feefeffe
3ffffa50: feefeffe feefeffe feefeffe feefeffe
3ffffa60: feefeffe feefeffe feefeffe feefeffe
3ffffa70: feefeffe feefeffe feefeffe feefeffe
3ffffa80: feefeffe feefeffe feefeffe feefeffe
3ffffa90: feefeffe feefeffe feefeffe feefeffe
3ffffaa0: feefeffe feefeffe feefeffe feefeffe
3ffffab0: feefeffe feefeffe feefeffe feefeffe
3ffffac0: feefeffe feefeffe feefeffe feefeffe
3ffffad0: feefeffe feefeffe feefeffe feefeffe
3ffffae0: feefeffe feefeffe feefeffe feefeffe
3ffffaf0: feefeffe feefeffe feefeffe feefeffe
3ffffb00: feefeffe feefeffe feefeffe feefeffe
3ffffb10: feefeffe feefeffe feefeffe feefeffe
3ffffb20: feefeffe feefeffe feefeffe feefeffe
3ffffb30: feefeffe feefeffe feefeffe feefeffe
3ffffb40: feefeffe feefeffe feefeffe feefeffe
3ffffb50: feefeffe feefeffe feefeffe feefeffe
3ffffb60: feefeffe feefeffe feefeffe feefeffe
3ffffb70: feefeffe feefeffe feefeffe feefeffe
3ffffb80: feefeffe feefeffe feefeffe feefeffe
3ffffb90: feefeffe feefeffe feefeffe feefeffe
3ffffba0: feefeffe feefeffe feefeffe feefeffe
3ffffbb0: feefeffe feefeffe feefeffe feefeffe
3ffffbc0: feefeffe feefeffe feefeffe feefeffe
3ffffbd0: feefeffe feefeffe feefeffe feefeffe
3ffffbe0: feefeffe feefeffe feefeffe feefeffe
3ffffbf0: feefeffe feefeffe feefeffe feefeffe
3ffffc00: feefeffe feefeffe feefeffe feefeffe
3ffffc10: feefeffe feefeffe feefeffe feefeffe
3ffffc20: feefeffe feefeffe feefeffe feefeffe
3ffffc30: feefeffe feefeffe feefeffe feefeffe
3ffffc40: feefeffe feefeffe feefeffe feefeffe
3ffffc50: feefeffe feefeffe feefeffe feefeffe
3ffffc60: feefeffe feefeffe feefeffe feefeffe
3ffffc70: feefeffe feefeffe feefeffe feefeffe
3ffffc80: feefeffe feefeffe feefeffe feefeffe
3ffffc90: feefeffe feefeffe feefeffe feefeffe
3ffffca0: feefeffe feefeffe feefeffe feefeffe
3ffffcb0: feefeffe feefeffe feefeffe feefeffe
3ffffcc0: feefeffe feefeffe feefeffe feefeffe
3ffffcd0: feefeffe feefeffe feefeffe feefeffe
3ffffce0: feefeffe feefeffe feefeffe feefeffe
3ffffcf0: feefeffe feefeffe 402366ff 00000001
3ffffd00: ffffffff 00000000 3ffe95b1 00000008
3ffffd10: 4023674e 3ffefa94 3ffefa94 00000000
3ffffd20: 000005e0 00000040 40104111 3ffed5e0
3ffffd30: 0000013a 00000000 00000000 000000fc
3ffffd40: 00000087 00000001 40105259 3ffed5e0
3ffffd50: 3ffed5b0 00000000 00000000 3ffefa8a
3ffffd60: 3ffecbf8 00000000 00000000 40102074
3ffffd70: 40104e3e 3ffed5e0 40104111 3ffed5e0
3ffffd80: 00000005 00000000 00000020 40100224
3ffffd90: 00000020 40100224 00000005 40102074
3ffffda0: 3ffe9465 4010530b 3ffecef0 401052f3
3ffffdb0: 40104203 00040000 00000000 00040000
3ffffdc0: 00002000 40104200 00040000 40102ddc
3ffffdd0: 3ffed628 40103167 00000000 40102074
3ffffde0: 00007fff 003adf4c 40103296 00000100
3ffffdf0: 3ffe9d10 2c9f0300 4000050c 3fffc278
3ffffe00: 40102fb8 3fffc200 00000022 00080000
3ffffe10: 4020657c 00000030 00000000 ffffffff
3ffffe20: 40207570 000c3500 00002119 978beb84
3ffffe30: 00004bc6 00000000 00000000 fffffffe
3ffffe40: 00000000 3fffc6fc 00000000 3ffe8804
3ffffe50: 00000000 00000002 3ffffedf 40207570
3ffffe60: 3ffffee0 00000000 3fffd9d0 3ffeec98
3ffffe70: 00000000 00000000 00000001 3ffeeb54
3ffffe80: 40205024 3ffffede 3ffeeb54 40205030
3ffffe90: 40205024 3ffffede 3ffeeb54 40205278
3ffffea0: 00000006 3ffffede 0000000a 4020529c
3ffffeb0: 0000017e 0000017e 3ffe85e4 401008a3
3ffffec0: 3ffeeaf0 00000047 3ffeec98 000000ff
3ffffed0: 00000000 00000020 3fff007c 40100a82
3ffffee0: ffffff00 3fff007c 3ffefcf4 40100478
3ffffef0: 00000009 0000002e 3ffef92c 402189cc
3fffff00: 000000bb 3fffff92 0000000b 40210aed
3fffff10: 3fffff90 40204a9d 00000020 402115f8
3fffff20: 3ffe8935 3ffeea9c 00000008 40211812
3fffff30: 00000000 3ffeea9c 3ffefa94 3ffeec98
3fffff40: 007a1200 a116765b 3ffeea00 40211843
3fffff50: 40105ce9 00208e6f 3ffeed00 00000000
3fffff60: 3ffee630 3ffeed00 000003e8 3ffeed00
3fffff70: 3fffdad0 3ffeec98 40206494 3fffefa0
3fffff80: 3ffeed00 3fffdad0 3ffeec98 40206bba
3fffff90: 3fffdad0 00000000 3ffeec84 40201228
3fffffa0: feefeffe 00000000 3ffeec84 402065c4
<<<stack<<<

--------------- CUT HERE FOR EXCEPTION DECODER ---------------

ets Jan 8 2013,rst cause:2, boot mode:(3,6)

load 0x4010f000, len 3460, room 16 tail 4 chksum 0xcc load 0x3fff20b8, len 40, room 4 tail 4 chksum 0xc9 csum 0xc9 v00048250 ~ld

Answer 1

Good catch

In fact, if you read the Important things to remember section of the README for the ESPAsyncWebServer , you'll find that it says:

You can not use yield or delay or any function that uses them inside the callbacks

So no, you must not use delay() or yield() inside a callback from the ESPAsyncWebServer. ESPAsyncWebServer runs in its own task; delay() and yield() don't work correctly with it, as you saw.

In fact you should do as little as possible inside a callback from the async web server. You should not call any networking code (for instance, don't initiate an HTTP connection to another server), call any functions or classes that you don't know for sure do not call delay() or yield() , and you should not perform any long running operations. You also shouldn't declare large variables as the callback has its own, limited stack space that you'll be using. It is safe to call Serial functions, though.

If you need to do any of these things, you should restructure your code to move the work out of the callback and into loop() or its own task (if you understand how to do that; if you don't, loop() is fine). If the web browser needs to display the results of the work you should fetch it asynchronously rather than block the callback to return it.

If for some reason you absolutely have to delay the execution in the callback, you can write a loop testing millis() :

time_t completion_time = millis() + DELAY_TIME;
while(millis() < completion_time) ;

This will throw a watchdog timer exception if you do it for too long. If you absolutely need to do this you should really reconsider why and restructure your code so that you don't.