Using new/delete within the 'on' statement causes a memory leak.

[AchcarLucas]

Platform

ESP32

IDE / Tooling

Arduino (IDE/CLI)

What happened?

I have the following code

AsyncCallbackWebHandler& RawRequest::onServer() {
    // PAGE 'raw data' http://[IP-DO-ESP]/raw?page={page}
    return this->webServer->on("/raw", HTTP_GET, [this](AsyncWebServerRequest *request) {
        STARTING_SERVER_PROCESSING();

        uint16_t limit = 10;
        uint16_t currentPage = 1;

        if (request->hasParam("page")) {
            currentPage = request->getParam("page")->value().toInt();
            if (currentPage < 1) {
                currentPage = 1;
            }
        }

        uint32_t totalPages = this->getDataMonitor()->getTotalPages(limit);
        std::list<Sample> samples = this->getDataMonitor()->selectSamples(currentPage, limit);

        Serial.println("Current Page: " + String(currentPage) + " Total Pages: " + String(totalPages));

        RawPage rawPage = RawPage(
            DATABASE,
            currentPage,
            totalPages,
            limit,
            &samples
        );

        request->send(200, "text/html", rawPage.page());

        FINISH_SERVER_PROCESSING();
    });
}

If rawPage is created with new

AsyncCallbackWebHandler& RawRequest::onServer() {
    // PAGE 'raw data' http://[IP-DO-ESP]/raw?page={page}
    return this->webServer->on("/raw", HTTP_GET, [this](AsyncWebServerRequest *request) {
        STARTING_SERVER_PROCESSING();

        uint16_t limit = 10;
        uint16_t currentPage = 1;

        if (request->hasParam("page")) {
            currentPage = request->getParam("page")->value().toInt();
            if (currentPage < 1) {
                currentPage = 1;
            }
        }

        uint32_t totalPages = this->getDataMonitor()->getTotalPages(limit);
        std::list<Sample> samples = this->getDataMonitor()->selectSamples(currentPage, limit);

        Serial.println("Current Page: " + String(currentPage) + " Total Pages: " + String(totalPages));

        Page *rawPage = new RawPage(
            DATABASE,
            currentPage,
            totalPages,
            limit,
            &samples
        );

        request->send(200, "text/html", rawPage->page());
        delete rawPage

        FINISH_SERVER_PROCESSING();
    });
}

Even with the delete function at the end, a memory leak still occurs.

AchcarLucas/Flow-Control-System@2ba8941

Above is the commit I had to make (converting everything to local) to remove the memory leak.

Stack Trace

Memory Leak

Minimal Reproductible Example (MRE)

Memory Leak

I confirm that:

• I have read the documentation.
• I have searched for similar discussions.
• I have searched for similar issues.
• I have looked at the examples.
• I have upgraded to the lasted version of ESPAsyncWebServer (and AsyncTCP for ESP32).

[AchcarLucas]

OBS: https://chatgpt.com/share/69d89a37-15d0-83e9-a6c4-42782ae07540
Does this make sense? If so, a note should be made in the library about the problem.

[mathieucarbou]

OBS: https://chatgpt.com/share/69d89a37-15d0-83e9-a6c4-42782ae07540 Does this make sense? If so, a note should be made in the library about the problem.

I cannot read

The server is asynchronous. When you call send() the response is not immediately send because the response has to go through all the middleware chain first. So to be aware of the end of a request (when you can clear allocated memory) you need to use request->onDisconnect() callback.
Look at the examples in the project, there are some of that.

[AchcarLucas]

Okay, in that case, I think it's best to keep the allocation local.

[AchcarLucas]

OBS: I also noticed that my platform is pointing to the old repository. I'll try pointing it to the current one here, but I think it should be as you said, a delete within the asynchronous method.

Thank you for your help.