Close database connection for thread after thread is finished.

app/models/scheduler.rb

@@ -57,6 +57,7 @@ class Scheduler < ApplicationModel
       job.pid = ''
       job.save
       logger.info " ...stopped thread for '#{job.method}'"
+      ActiveRecord::Base.connection.close
     }
   end
 

lib/import/otrs2.rb

@@ -377,6 +377,7 @@ module Import::OTRS2
           end
           _ticket_result(records, locks)
         end
+        ActiveRecord::Base.connection.close
       }
     }
     (1..thread_count).each {|thread|

lib/sessions.rb

@@ -498,6 +498,7 @@ returns
             thread_client(client_id)
             @@client_threads[client_id] = nil
             puts "close client (#{client_id}) thread"
+            ActiveRecord::Base.connection.close
           }
           sleep 0.5
         end