Configure threads to not abort on exceptions

[ayufan]

This solves long outstanding issue: #396.

This happens, because some applications or gems do overwrite global setting of Thread.abort_on_exception= which is by default set to false.
This leads to application process to exit and making the spring unable to recover from that.

Examples of such:

• https://github.com/alexdalitz/dnsruby/blob/master/lib/dnsruby/select_thread.rb#L27
• https://github.com/ruby-concurrency/concurrent-ruby/blob/master/lib/concurrent/thread_safe/synchronized_delegator.rb#L26

[rails-bot]

Thanks for the pull request, and welcome! The Rails team is excited to review your changes, and you should hear from @jonleighton (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[jonleighton]

This seems good, thanks. Some comments:

• Please add to the changelog file
• I suggest extracting all the repetitive code into a Spring.failsafe_thread { ... } method

[ayufan]

Updated. Can you review @jonleighton?

[tycooon]

I tried this fork in my app (see #466), but no luck. Actually, this version just doesn't work: it tries to reload app right after i run rspec (even though i didn't change any files) and hangs the same way it does in original version.

[ayufan]

It seems strange, because your problem seems very similar to mine. Can you post maybe more logs? Also can you post what gems are you using?

[tycooon]

Here is the log: https://gist.github.com/tycooon/61a711940539643bb17b9151a4cffe7d
I stopped spring and then started/closed rails console several times (it hanged on the 3rd attempt).

[ayufan]

@tycooon Are you sure that you are using my changes?

[tycooon]

Yes, I've put gem "spring", github: "ayufan/spring" in my Gemfile and run bundle. And spring's behavior actually changed, it doesn't work.

[jonleighton]

Yes, I've put gem "spring", github: "ayufan/spring" in my Gemfile and run bundle. And spring's behavior actually changed, it doesn't work.

This is not a supported way of using spring. If you want to test this branch, you'll need to check it out and build and install the gem manually.

[tycooon]

OK, now I made these steps:

git clone https://github.com/ayufan/spring
cd spring && gem build spring.gemspec
gem uninstall spring
gem install --local ./spring-1.7.1.gem

Now it doesn't die when I run rails c several times but still hangs after trying to reload app after touch Gemfile (the same behavior as original 1.7.1 version). Here is the log: https://gist.github.com/tycooon/aa8cba7947563d52bb113304216ef38c

[ayufan]

@tycooon Strange. It works without any problems for me now :)

Maybe you can post your gems?

[jonleighton]

I've released 1.7.2 with this fix, so you can try that. Thanks!