High CPU Usage when signed in to Xbox since 1.19.40

[GameParrot]

Describe the bug
When signed in to Xbox live, the game uses way more CPU than it should.

To Reproduce
Steps to reproduce the behavior:

1. Open the game
2. Check CPU usage when signed out
3. Sign in
4. Check CPU usage again

Expected behavior
The CPU usage should not be super high when signed in.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: Linux
• Version 0.8.0
• Installation Type Built from source. Also occurs with Appimage and Flatpak.

Additional context
The thread consuming CPU usage is REST Thread(0). strace shows a lot of EAGAIN (Resource temporarily unavailable) errors on the thread. This is likely related to the Microsoft account disconnected message that also started in 1.19.40 that is shown when in the pause menu of a singleplayer world.

[ChristopherHX]

Maybe you need to implement the websocket java api in c++? It was recently added to the game, but I ignored it.

[GameParrot]

Would stubbing the websocket functions resolve the high CPU usage?

[ChristopherHX]

Probably not, websocket functions are already stubbed by automation.

strace shows a lot of EAGAIN (Resource temporarily unavailable) errors on the thread

Which libc function returns that error?
You could insert a sleep command into libc-shim if it returns EAGAIN and the thread will sleep instead of using your cpu time.
I have no idea and not even noticed the high cpu usage.

[GameParrot]

It doesn't look like EAGAIN errors are coming through libc-shim, maybe they are being generated in the launcher's code, not the game's code

[GameParrot]

Also, reverting the async xbox http client fixes the cpu usage, but makes skins and marketplace not load. gdb also shows the write function failed crash that sometimes happens when closing the game occurring on the REST Thread(0).

[GameParrot]

Maybe you need to implement the websocket java api in c++? It was recently added to the game, but I ignored it.

What WebSocket library should be used for something like this? I was able to fix the CPU usage issue by having it call onOpen when websocket connect is called, but nothing else. I stubbed the rest of the symbols for now.

[ChristopherHX]

You could use libcurl, it has expermental websocket support. I started trying to implement it, meanwhile I have more important things to do.

You could use the -DUSE_OWN_CURL=ON cmake flag (+ a flag to enable building websocket support, -DCURL_EXT_EXTRA_OPTIONS=-DENABLE_WEBSOCKETS=ON) to build a recent enough version from sources as part of the build, used by 32bit mcpelauncher-client32 on the AppImage. This wouldn't add any completly new dependency, but the build system needs to be changed to use that flag.

[GameParrot]

Where can I find a websocket example program using libcurl? I can't seem to find one.

[ChristopherHX]

That's true it is hard to find examples at this time.
You can find websocket tests in the curl sourcecode, they show how to use it.

• https://github.com/curl/curl/blob/df3722a46c678b5c54b3df1154c1d109ad4cb6e5/tests/libtest/lib2301.c#L110
• https://github.com/curl/curl/blob/df3722a46c678b5c54b3df1154c1d109ad4cb6e5/tests/libtest/lib2302.c#L27

[GameParrot]

I started trying to implement it, meanwhile I have more important things to do.

Can you put what you have in a new branch?

[ChristopherHX]

I don't have much, nothing I ever tested. It seems to be important to handle text and binary messages differently.

    // auto m = curl_ws_meta(nullptr);
    // if(m->flags & CURLWS_BINARY) {
        
    // }

    // curl_easy_setopt(curl, CURLOPT_URL, URL);

    // /* use the callback style */
    // curl_easy_setopt(curl, CURLOPT_USERAGENT, "webbie-sox/3");
    // curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    // curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writecb);
    // curl_easy_setopt(curl, CURLOPT_WRITEDATA, curl);
    // res = curl_easy_perform(curl);

Seems like I altered ext/curl.cmake

ExternalProject_Add(
        curl_ext
        URL "http://curl.haxx.se/download/curl-7.87.0.tar.gz"
        INSTALL_DIR ${CMAKE_BINARY_DIR}/ext/curl
        CMAKE_ARGS "-DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}/ext/curl" "-DBUILD_CURL_EXE=OFF" "-DBUILD_SHARED_LIBS=OFF" "-DCURL_STATICLIB=ON" "-DCURL_DISABLE_LDAP=ON" "-DCMAKE_USE_LIBSSH2=OFF" "-DCMAKE_USE_OPENLDAP=OFF" "-DUSE_LIBIDN2=OFF" "-DENABLE_WEBSOCKETS=ON" "-DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}" "-DCMAKE_LINK_FLAGS=${CMAKE_LINK_FLAGS}" "-DCMAKE_LIBRARY_ARCHITECTURE=${CMAKE_LIBRARY_ARCHITECTURE}" ${CURL_EXT_EXTRA_OPTIONS}
)

But CURL_EXT_EXTRA_OPTIONS should also work.

I would use a writecb to call the message received java callbacks.

Trust me that mostly nothing.

[GameParrot]

I put a temporary fix for the CPU usage that can be used until websocket support is added at minecraft-linux/mcpelauncher-client#42

[GameParrot]

Regarding websocket, the source code for libhttpclient (what the game uses) is at https://github.com/microsoft/libHttpClient. Files for websocket can be found at https://github.com/microsoft/libHttpClient/blob/75dc4785c9f51af04b2dafad33579067f7fe4443/Build/libHttpClient.Android/src/main/java/com/xbox/httpclient/HttpClientWebSocket.java and https://github.com/microsoft/libHttpClient/tree/main/Source/WebSocket