Comment by DanielHB

Comment by DanielHB 3 days ago

15 replies

View on Hacker News

From my understanding the main difference between electron and other WebView Containers (besides built-in APIs) is that electron runs your nodejs code in the same process as your browser code.

So there is no cross-process communication, true synchronous communication between browser and nodejs code, ability to communicate without copying memory and without serialization, etc. All these capabilities are essential if you do a lot of processing between the two sides. It is also why electron must bundle a browser (and its v8 engine) and can't rely on the OS browser like other solutions do (which might not be v8 or might be the wrong version of v8).

From my understanding this is not the case of any other WebView wrappers tech (Tauri, Wails). Which makes them unsuitable for some kinds of applications (invoking a function cross-process is extremely slow).

I am not sure how correct I am with these claims as I never did a lot of electron. If you have a deeper insight I am quite curious about the topic.

koito17 3 days ago

In the case of Electron, there is a "main process" that is a Node.js process. This process has the capability to spawn "renderer processes", each browser window is a "renderer process". Through ipcMain and ipcRenderer, Node and Chromium have bidirectional comminication.

I don't think renderer processes run Node. Per the documentation,

  [C]ode ran in renderer processes should behave according to web standards ... [T]he renderer has no direct access to require or other Node.js APIs
https://www.electronjs.org/docs/latest/tutorial/process-mode...
Reply View 4 replies
  • killcoder 3 days ago

    Renderers can access Node APIs via the ‘node integration’ setting or via a preload script.

    Reply View 2 replies
    • themoonisachees 3 days ago

      Aren't these just IPCs disguised as normal function calls though? IIRC only the main node process does anything node, renderers can call "node functions" that really happen in the main process.

      Reply View 1 reply
      • killcoder 2 days ago

        Not at all, in a renderer the Node and Chromium event loops are bound together, they’re part of the same v8 isolate, no IPC shenanigans.

        The main process really shouldn’t be used for anything except setup. Since it controls gpu paints amongst other things, blocking on it will cause visible stuttering and a bad user experience.

        https://www.electronjs.org/blog/electron-internals-node-inte...

        Reply View 0 replies
  • notpushkin 3 days ago

    > Renderer processes can be spawned with a full Node.js environment for ease of development. Historically, this used to be the default, but this feature was disabled for security reasons.

    Makes sense.

    Reply View 0 replies
__jonas 3 days ago

>From my understanding the main difference between electron and other WebView Containers (besides built-in APIs) is that electron runs your nodejs code in the same process as your browser code.

That is not correct: https://www.electronjs.org/docs/latest/tutorial/process-mode...

> So there is no cross-process communication, true synchronous communication between browser and nodejs code, ability to communicate without copying memory and without serialization, etc

From the Electrton docs:

> Arguments will be serialized with the Structured Clone Algorithm, just like window.postMessage, so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.

(https://www.electronjs.org/docs/latest/api/ipc-renderer#ipcr...)

But yes they do build pretty heavily on Chromium, so swapping it out for a system WebView would probably not be possible.

Reply View 6 replies
  • killcoder 3 days ago

    Within a renderer you can access NodeJS APIs directly. The main process shouldn’t be used for any significant computation, as it will block GPU paints and cross-process synchronisation.

    The other main difference is Electron bundles a known set of APIs, given the known Chromium version. There’s such a huge variance of supported features across the embedded web views.

    Reply View 2 replies
    • cyanydeez 3 days ago

      Yes, this is the best benefit of elecrron: you dont have to trouble shoot 10s of OS webview versions and their ixremental suppory, especially with MacOS.

      But it is right that the ui for elwctron has to use a IPC layer to get a node backend running. However, chrome is moving a lot of things like FilesystemAPI into browsers so there may be a day were nodejs is dropped in favor of a sandboxed chromium.

      Reply View 1 reply
  • DanielHB 3 days ago

    oh wow, I was very wrong, I don't know why I got this notion that electron shared the runtime environment between non-browser and browser code. Thanks for the clarification.

    I am pretty disappointed about this, it severely limits the usability of native code from inside the UI code and makes Electron much less attractive compared to Tauri, Wails or similar alternatives.

    Do you know if at least moving objects between the electron processes uses direct memory-copying and not some heavy-handed serialization (Wails for example serializes to JSON). The links you pointed out don't mention that.

    Reply View 2 replies
    • killcoder 3 days ago

      You were correct. Electron lets you expose specific NodeJS APIs via the preload script or everything via the ‘nodeIntegration’ setting:

      https://www.electronjs.org/docs/latest/api/structures/web-pr...

      Separately the IPC lets you do zero copy in some circumstances via Transferable objects such as ArrayBuffers. Structured cloning is efficient but not zero copy, and json serialisation shouldn’t be used (since structured cloning is easily available).

      Reply View 1 reply
      • __jonas 3 days ago

        Thanks for adding this context! Guess I was mislead by the Electron documentation talking about multiple processes and IPC, appreciate the clarification!

        Reply View 0 replies
baumschubser 3 days ago

In a recent podcast, Daniel Thompson from Tauri talks about the perspective of having shared memory between the Webview and the backend in Tauri as well. However, it is pretty vague.

See here, search for "Topic 12": https://syntax.fm/show/821/is-tauri-the-electron-killer/tran...

Reply View 2 replies
  • cyanydeez 3 days ago

    You can used shared buffers in chrome so one could use webworkers for a lot of processing. However, we are still waiting for many Apis to be available in webworkers.

    Reply View 1 reply
    • DanielHB 3 days ago

      What you really want is to get a reference to those SharedArrayBuffers in the native code like you can do with WASM

      Reply View 0 replies