Any HTTP request takes 2 seconds on ESP8266

Projects Programming
1

I'm trying to program an ESP8266 device to be able to take commands over HTTP with ESP8266WebServer but no matter what I do any request takes 2 seconds to complete.

Upon further investigation I noticed there are the following headers in the response:

Connection: keep-alive
Keep-Alive: timeout=2000

I tried adding a Connection: close header manually but it just ended up adding both and still taking 2s to complete the request.

I also tried looking at the source code and I found HTTP_MAX_CLOSE_WAIT but if I try to define it in my code I get the following warning when compiling, and the request still takes 2s

warning: "HTTP_MAX_CLOSE_WAIT" redefined
    1 | #define HTTP_MAX_CLOSE_WAIT 0

I also tried manually closing the connection after returning the response, which also did not help and had a side effect of the server stopping to respond for some reason.

http.send(200, "text/plain", "test");
http.close();

Additionally, I'm having the same issue when I try to send an HTTP request from the ESP to another server, each request takes 2s.

I had started a PHP dev server php -S <addr>, and added some simple code to send an HTTP request to it every time a pin changes:

void setup() {
  pinMode(D4, INPUT_PULLUP);
}

int oldv;

void loop() {
  int val = digitalRead(D4);
  if (val != oldv) {
    oldv = val;
    request("<ip>", 4444, "/test", "");
  }
}

void request(String host, int port, String uri, String body, bool https = false) {
  WiFiClient client;
  HTTPClient http;

  http.setReuse(false);
  http.begin(client, host, port, uri, https);
  http.POST(body);
  http.end();
}

But no matter how fast I trigger the pin, requests come in only once per 2s:

[Mon Jan  1 17:19:16 2024] 192.168.1.1:53935 Accepted
[Mon Jan  1 17:19:16 2024] 192.168.1.1:53935 [404]: (null) /test - No such file or directory
[Mon Jan  1 17:19:16 2024] 192.168.1.1:53935 Closing
[Mon Jan  1 17:19:18 2024] 192.168.1.1:64024 Accepted
[Mon Jan  1 17:19:18 2024] 192.168.1.1:64024 [404]: (null) /test - No such file or directory
[Mon Jan  1 17:19:18 2024] 192.168.1.1:64024 Closing
[Mon Jan  1 17:19:20 2024] 192.168.1.1:61577 Accepted
[Mon Jan  1 17:19:20 2024] 192.168.1.1:61577 [404]: (null) /test - No such file or directory
[Mon Jan  1 17:19:20 2024] 192.168.1.1:61577 Closing
[Mon Jan  1 17:19:22 2024] 192.168.1.1:65345 Accepted
[Mon Jan  1 17:19:22 2024] 192.168.1.1:65345 [404]: (null) /test - No such file or directory
[Mon Jan  1 17:19:22 2024] 192.168.1.1:65345 Closing

How can I speed things up?

2

You know the meaning of 404 ?

3

How is that relevant?

4

I'd suggest you install wireshark and analyse the http traffic. It looks like your client waits for the 2s timeout till it detects that the server has closed the connection, so it might either ignore 404 or does not receive it at all. You could remove the two header lines (Connection: & Keep-alive:) and see if something changes.

5

Ahh.. Yet another example of how bad going down a rabbit hole is.

It turned out I had a call to delay in the main loop function which I overlooked for hours and hours..

I had a good clue that both as a server and as a client requests were taking the same time, so I could have figured it earlier but, oh well, hope this saves someone some time!