Try running once off jobs outside of db:migrate

app/jobs/onceoff.rb

@@ -10,15 +10,21 @@ class Jobs::Onceoff < Jobs::Base
     job_name = self.class.name_for(self.class)
 
     if args[:force] || !OnceoffLog.where(job_name: job_name).exists?
-      execute_onceoff(args)
-      OnceoffLog.create(job_name: job_name)
+      DistributedMutex.synchronize(self.class.name) do
+        execute_onceoff(args)
+        OnceoffLog.create(job_name: job_name)
+      end
     end
   end
 
   def self.enqueue_all
+    previously_ran = OnceoffLog.pluck(:job_name).uniq
+
     ObjectSpace.each_object(Class).select { |klass| klass < self }.each do |klass|
-      job_name = name_for(klass).underscore.to_sym
-      Jobs.enqueue(job_name)
+      job_name = name_for(klass)
+      unless previously_ran.include?(job_name)
+        Jobs.enqueue(job_name.underscore.to_sym)
+      end
     end
   end
 

app/jobs/scheduled/enqueue_onceoffs.rb

@@ -0,0 +1,11 @@
+module Jobs
+
+  class EnqueueOnceoffs < Jobs::Scheduled
+    every 10.minutes
+
+    def execute(args)
+      Jobs::Onceoff.enqueue_all
+    end
+  end
+
+end

lib/tasks/db.rake

@@ -7,8 +7,6 @@ end
 task 'db:migrate' => ['environment', 'set_locale'] do
   SeedFu.seed
 
-  Jobs::Onceoff.enqueue_all
-
   SiteSetting.last_vacuum = Time.now.to_i if SiteSetting.last_vacuum == 0
 
   if SiteSetting.vacuum_db_days > 0 &&