Скачать или смотреть How to Dynamically Load a Side Module Larger Than 4KB in WebAssembly

Learn how to handle side modules larger than `4KB` in WebAssembly using `loadDynamicLibrary()` and `Asyncify`.
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Dynamically Load Large Side Modules in WebAssembly

WebAssembly is a powerful tool for running code in the web environment, but when it comes to downloading larger libraries, developers may run into limitations. One common issue is loading side modules that exceed 4KB in size. In this post, we’ll explore a solution to this problem and provide an example code demonstrating how to implement it effectively.

The Problem: dlopen() and the 4KB Limit

When attempting to dynamically load a side module using the dlopen() function in WASM, you may encounter the following error message in your browser console:

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This indicates that due to the constraints of dlopen(), loading a library larger than 4KB cannot be done on the main thread. This can be quite limiting when working on larger applications or modules.

Solution Overview

To bypass the 4KB limitation imposed by dlopen(), we can use the following methods:

Utilize the loadDynamicLibrary() function.

Implement the Asyncify feature to allow asynchronous handling of library loading.

Step-by-Step Implementation

Step 1: Setting Up Your Files

You will need four main files for this solution:

main.c: The main module file.

side.c: The side module file that you want to load.

index.html: The HTML file to host the web application.

Makefile: To build your project using Emscripten.

Step 2: Writing the Side Module (side.c)

This is your side module, which we will load dynamically. Here, we've set a size of 5000 bytes.

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Step 3: Writing the Main Module (main.c)

This file demonstrates how to load the side module asynchronously using loadDynamicLibrary().

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Step 4: HTML Structure (index.html)

Here's a simple structure for your HTML file which includes a button for loading the library:

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Step 5: Creating the Makefile

Your Makefile should handle the building of both side.c and main.c. Here’s an example:

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Step 6: Running Your Application

Build your application using the Makefile.

Open your browser and navigate to http://localhost:8080.

Use the "Choose File" button to select your side/side.wasm file and then click the "loadLibrary" button.

You should see output in the console indicating the successful loading of the side module:

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Conclusion

By leveraging the loadDynamicLibrary() method combined with Asyncify, you can successfully load side modules larger than 4KB without running into threading issues. This method not only addresses the size limitation but also enhances the performance of your WebAssembly applications.

Now you can incorporate larger libraries into your WebAssembly projects with ease!