doesn't work with `mini_racer` gem

[brodock]

With therubyracer it works fine, but not with mini_racer gem. It 'freezes' and never finishes the build. mini_racer works perfectly fine with rails sprockets.

[stevenosloan]

What versions or Middleman, Middleman::Sprockets, Sprockets, and MiniRacer are you using?

I've set up a minimal app to do some testing, and found that there was a fix in MiniRacer 0.1.7 (that does affect us) to prevent hanging (https://github.com/discourse/mini_racer/blob/master/CHANGELOG#L3-L5). It'll take a bit more digging to figure out what's causing the issue, but hopefully updating MiniRacer fixes the issue for now?

[brodock]

@stevenosloan I was trying with "latest" everything. You can check the code here (it's open): https://gitlab.com/rubyonrails-brasil/rubyonrails-brasil.gitlab.io/blob/492de52acb399ff961954ae6a0c00f07aeef37d1/Gemfile

running it in "development" works, but running the build rake task doesn't.
(make sure you checkout the 492de52acb399ff961954ae6a0c00f07aeef37d1 commit, which is one before I changed from mini_racer to therubyracer so I can actually release the changes)

[stevenosloan]

Ah great, thanks for that example.

Still need to do some digging to see if there's a fix, but it's looking like the Parallel gem and MiniRacer don't play nice and Parallel hangs waiting for the process here. For now, if you add --no-parallel to the build command, things won't lock up.

[le0pard]

Here some logs from stuck parallel build:

== Instrument (sitemap.manipulator): 746.893ms
{:name=>:asset_hash}
== Running manipulator: sitemap_move_files (101)
== Running manipulator: collections (110)
== Running manipulator: routing (130)
== Instrument (sitemap.update): 2360.763ms
{:reasons=>[:touched_file, :registered_new_manipulator_front_matter, :registered_new_manipulator_sitemap_ondisk, :registered_new_manipulator_sitemap_import, :registered_new_manipulator_sitemap_endpoint, :registered_new_manipulator_sitemap_proxies, :registered_new_manipulator_sitemap_redirects, :registered_new_manipulator_sitemap_move_files, :registered_new_manipulator_sitemap_ignore, :registered_new_manipulator_routing, :registered_new_manipulator_collections, :first_run_change_ignore, :registered_new_manipulator_blog_blog1_articles, :registered_new_manipulator_blog_blog1_tags, :registered_new_manipulator_blog_blog1_calendar, :registered_new_manipulator_blog_blog1_paginate, :registered_new_manipulator_sprockets, :registered_new_manipulator_asset_hash]}
== Instrument (builder.setup): 2849.4359999999997ms
{}
== Instrument (builder.queue): 1263.3190000000002ms
{}
== Prerendering CSS
== Request: /css/ui-8cbf3345.css
== Request: /css/audio-08f55ab4.css
== Request: /css/application-8f6fedff.css
== Finishing Request: css/audio-08f55ab4.css (0.0s)
== Finishing Request: css/ui-8cbf3345.css (0.0s)
== Finishing Request: css/application-8f6fedff.css (0.0s)
   identical  build/css/audio-08f55ab4.css
== Instrument (builder.output.resource): 300.984ms
{:path=>"audio-08f55ab4.css"}
WARNING: V8 isolate was forked, it can not be disposed and memory will not be reclaimed till the Ruby process exits.
   identical  build/css/ui-8cbf3345.css
== Instrument (builder.output.resource): 336.295ms
{:path=>"ui-8cbf3345.css"}
   identical  build/css/application-8f6fedff.css
== Instrument (builder.output.resource): 342.215ms
{:path=>"application-8f6fedff.css"}
WARNING: V8 isolate was forked, it can not be disposed and memory will not be reclaimed till the Ruby process exits.
WARNING: V8 isolate was forked, it can not be disposed and memory will not be reclaimed till the Ruby process exits.

[guillerodriguez]

Ah great, thanks for that example.

Still need to do some digging to see if there's a fix, but it's looking like the Parallel gem and MiniRacer don't play nice and Parallel hangs waiting for the process here. For now, if you add --no-parallel to the build command, things won't lock up.

As of version 0.4.0, the mini_racer gem supports a new "single_threaded" flag that fixes this without the need to pass --no-parallel to the build command. This can be set in the config.rb file:

MiniRacer::Platform.set_flags! :single_threaded