Switch default quiet signal to TSTP as it is available on JRuby, fixes #3302 (#3302)

lib/sidekiq/api.rb

@@ -748,7 +748,7 @@ module Sidekiq
     end
 
     def quiet!
-      signal('USR1')
+      signal('TSTP')
     end
 
     def stop!

lib/sidekiq/cli.rb

@@ -43,6 +43,10 @@ module Sidekiq
       write_pid
     end
 
+    def jruby?
+      defined?(::JRUBY_VERSION)
+    end
+
     # Code within this method is not tested because it alters
     # global process state irreversibly.  PRs which improve the
     # test coverage of Sidekiq::CLI are welcomed.
@@ -51,8 +55,14 @@ module Sidekiq
       print_banner
 
       self_read, self_write = IO.pipe
+      sigs = %w(INT TERM TTIN TSTP)
+      # USR1 and USR2 don't work on the JVM
+      if !jruby?
+        sigs << 'USR1'
+        sigs << 'USR2'
+      end
 
-      %w(INT TERM USR1 USR2 TTIN).each do |sig|
+      sigs.each do |sig|
         begin
           trap sig do
             self_write.puts(sig)
@@ -135,6 +145,10 @@ module Sidekiq
       when 'USR1'
         Sidekiq.logger.info "Received USR1, no longer accepting new work"
         launcher.quiet
+      when 'TSTP'
+        # USR1 is not available on JVM, allow TSTP as an alternate signal
+        Sidekiq.logger.info "Received TSTP, no longer accepting new work"
+        launcher.quiet
       when 'USR2'
         if Sidekiq.options[:logfile]
           Sidekiq.logger.info "Received USR2, reopening log file"

lib/sidekiq/launcher.rb

@@ -61,8 +61,6 @@ module Sidekiq
 
     private unless $TESTING
 
-    JVM_RESERVED_SIGNALS = ['USR1', 'USR2'] # Don't Process#kill if we get these signals via the API
-
     def heartbeat
       results = Sidekiq::CLI::PROCTITLES.map {|x| x.(self, to_data) }
       results.compact!
@@ -110,11 +108,7 @@ module Sidekiq
 
         return unless msg
 
-        if JVM_RESERVED_SIGNALS.include?(msg)
-          Sidekiq::CLI.instance.handle_signal(msg)
-        else
-          ::Process.kill(msg, $$)
-        end
+        ::Process.kill(msg, $$)
       rescue => e
         # ignore all redis/network issues
         logger.error("heartbeat: #{e.message}")

test/test_api.rb

@@ -436,7 +436,7 @@ class TestApi < Sidekiq::Test
         data.stop!
         signals_string = "#{odata['key']}-signals"
         assert_equal "TERM", Sidekiq.redis{|c| c.lpop(signals_string) }
-        assert_equal "USR1", Sidekiq.redis{|c| c.lpop(signals_string) }
+        assert_equal "TSTP", Sidekiq.redis{|c| c.lpop(signals_string) }
       end
 
       it 'can enumerate workers' do

test/test_cli.rb

@@ -351,7 +351,7 @@ class TestCli < Sidekiq::Test
           count += 1
         }]
         @cli.launcher = Sidekiq::Launcher.new(Sidekiq.options)
-        @cli.handle_signal('USR1')
+        @cli.handle_signal('TSTP')
 
         assert_equal 1, count
       end

test/test_web.rb

@@ -81,7 +81,7 @@ class TestWeb < Sidekiq::Test
         assert_nil Sidekiq.redis { |c| c.lpop signals_key }
         post '/busy', 'quiet' => '1', 'identity' => identity
         assert_equal 302, last_response.status
-        assert_equal 'USR1', Sidekiq.redis { |c| c.lpop signals_key }
+        assert_equal 'TSTP', Sidekiq.redis { |c| c.lpop signals_key }
       end
 
       it 'can stop a process' do