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  1. Qt
  2. QTBUG-86271

[WebAssembly] Blocks on the main thread

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    Details

    • Type: Bug
    • Status: Reported
    • Priority: P2: Important
    • Resolution: Unresolved
    • Affects Version/s: 5.15.0
    • Fix Version/s: None
    • Component/s: Core: Event loop, Other
    • Labels:
      None
    • Environment:
      Qt for WebAssembly 5.15 with both emscripten 1.39.8 and 2.0.0
      Firefox 76 and later
      Chrome 84 and later
    • Platform/s:
      WebAssembly

      Description

      I've had some issues with Browser reporting problems ("A script is slowing down your browser") with a medium-sized Qt for WASM application.
      Due to this, I've tried compiling Qt for WebAssembly and my application with current emscripten 2.0.0.
      This version emits the following warning:

      Blocking on the main thread is very dangerous, see https://emscripten.org/docs/porting/pthreads.html#blocking-on-the-main-browser-thread
      qtloader.js:382:25

      I understand that Qt currently has no official support for other emscripten versions than the one mentioned at https://doc.qt.io/qt-5/wasm.html. However, I think this is a serious issue that probably also affects those versions and should be handled.|

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          Activity

            People

            Assignee:
            lpotter Lorn Potter
            Reporter:
            VersalEszett Julius Bullinger
            PM Owner:
            Veli-Pekka Heinonen Veli-Pekka Heinonen
            Votes:
            1 Vote for this issue
            Watchers:
            2 Start watching this issue

              Dates

              Created:
              Updated:

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