Inconsistent asset digest values about uglifier HOT 5 CLOSED

Assuming there is a bug in Uglifier variable mangling, you can disable it with {mangle: false} configuration option. This leaves variable names intact resulting in slightly larger code size after gzip.

Uglifier should always return the same output with same input. However, there are few things that I'm aware of that could break the setup in similar ways as you've described.

If you're caching compiled files on deployment environments, updating Uglifier version can change the minified output. Similarly, any compiled .erb.js files might be cached even when Ruby code it is calling is changed. You could try bumping config.assets.version in your application.rb to invalidate asset cached.

You didn't mention if disabling Uglifier fixes the issue, i.e. are there any differences in compiled JS before minification. If you haven't already done so, it'd be help to deploy without minification and compare those files on different nodes.

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Unless you mean caching the asset files for the client browser, this is not the case because i can see files being re-generated on the server, and i was also comparing files pulled from the servers file system, not from the browser.

I took two different compressed javascript files, which I then "uncompressed" by reformatting it and then used diff to see what the changes are. They were all seemingly variable name differences.

I could try disabling mangling, but that would kind of defeat the purpose here, right?
I understand that uglifier should always return the same output with the same input, but for some reason this is not happening for me. It kind of seems like it's and environment thing, but my ruby, rubygems and uglifier gem versions match across environments.

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What does uglifier use as an underlying library though? I would try to check if the native libraries are at the same versions to rule that issue out.

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Uglifier uses UglifyJS2. This is embedded in Uglifier and as such the version should be same on all nodes.

When I talked about caches, I meant Sprockets caches, not browser. Sprockets caches partial assets and in some deployment setups these can be persisted over deployments. E.g. if you include two libraries in your application libraries, the compiled versions of these libraries may be stored there. By bumping config.assets.version you can ensure that no stale and caches are used.

Disabling mangling only affects one aspect of the minification. Newlines and redundant code are still removed. To isolate the issue, you should try to disable mangling and even Uglifier itself if clearing caches doesn't help.

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I had this same issue and ultimately determined that the one node that was generating a different asset hash was running a different version of rake. Ensuring that all nodes had the same version of rake (which in our setup is managed outside of the Gemfile) solved the problem for me.

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