tricky_signals

This gem aims to solve the problem with...

logger = Logger.new(STDOUT)
trap('USR1') do
  logger.info 'hello!'
end

And then:

kill -USR1 <pid>

What we get:

log writing failed. can't be called from trap context

Looks familiar? Then tricky_signals is your friend!

Add this line to your application's Gemfile:

gem 'tricky_signals'

And then execute:

$ bundle

Or install it yourself as:

$ gem install tricky_signals

logger = Logger.new(STDOUT)

# ...

TrickySignals.global.trap(:USR1) do
  Thread.list.each do |thread|
    logger.debug { "Thread object_id=#{thread.object_id}" }
    if thread.backtrace
      logger.debug { thread.backtrace.join("\n") }
    else
      logger.debug '<no backtrace available>'
    end
  end
end

TrickySignals.global.untrap(:USR1)

TrickySignals.start! do |signals|
  signals.trap(:USR1) { }
  # subscribed to USR1
  signals.trap(:TTIN) { }
  # subscribed to TTIN
  # ...
end
# unsubscribed from USR1 and TTIN

signals = TrickySignals.start!
signals.trap(:USR1) { }
signals.trap(:TTIN) { }
# ...
signals.stop!
# unsubscribed from USR1 and TTIN

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/marshall-lee/tricky_signals.

The gem is available as open source under the terms of the MIT License.