Large webpage serving

[vatsake]

My whole webpage size is around 20k.
If I refresh the page twice quickly, the ESP will crash due to OOM.

I was wondering if there's any way to avoid this? For example serve 1 client at a time?

[mathieucarbou]

There are some examples also in the project about how to serve large content.

‘please have a look and in any case it would be best to share your code otherwise how could someone help you ? 🙃😉

[mathieucarbou]

Serving one client at a time is also possible : just add a middleware that will get a lock, then continue the filter chain, then register a disconnect callback on the request to release the lock.

‘another way would be to add a counter in the middleware and incrément it and décrément it a little like what is done for the rate limit.

[vatsake]

The chunked response looks interesting.

I tried an example with no luck. It sends ~half of the webpage and then crashes due to OOM.

server.on("/", HTTP_GET, [](AsyncWebServerRequest* request) {
    AsyncWebServerResponse* response = request->beginChunkedResponse(
      "text/html", [](uint8_t* buffer, size_t maxLen, size_t index) -> size_t {
        Serial.printf("%u / %u\n", index, strlen_P(HTTP_BODY));

        if (strlen_P(HTTP_BODY) <= index) {
          Serial.println("finished");
          return 0;
        }

        const int chunkSize = min((size_t)1024, min(maxLen, strlen_P(HTTP_BODY) - index));
        Serial.printf("sending: %u\n", chunkSize);

        memcpy(buffer, HTTP_BODY + index, chunkSize);
        return chunkSize;
      },
      rootProcessor);

    request->send(response);
    });

0 / 8448
sending: 952
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 0
952 / 8448
sending: 507
1459 / 8448
sending: 1
1460 / 8448
sending: 7
1467 / 8448
sending: 11
1478 / 8448
sending: 1024
2502 / 8448
sending: 60
2562 / 8448
sending: 12
2574 / 8448
sending: 15
2589 / 8448
sending: 1024
3613 / 8448
sending: 57
3670 / 8448
sending: 8
3678 / 8448
sending: 11
3689 / 8448
sending: 1024

User exception (panic/abort/assert)
--------------- CUT HERE FOR EXCEPTION DECODER ---------------

Unhandled C++ exception: OOM

[vatsake]

Oh I guess it's due to rootProcessor, without it, it send full page.

[vatsake]

Thanks again for the help!