update readme re: memory; change ancestor check to 25 at a time

README.md

@@ -19,6 +19,8 @@ AppConfig[:plugins] = ['some_plugin','aspace_sitemap']
 ### Note
 For users running ArchivesSpace versions older than v2.6.0, please note that slug related options are not available.
 
+Institutions with large numbers of published objects may need to increase the memory alloted to the application. See http://archivesspace.github.io/archivesspace/user/tuning-archivesspace/
+
 ## What does it do?
 The plugin adds a new job that generates a sitemap (at least one sitemap with a sitemap index)
 for the PUI. The file(s) can be downloaded and placed on a server of your choice for submission

backend/job_runners/aspace_sitemap_runner.rb

@@ -87,9 +87,9 @@ def run
 
       @job.write_output('Checking for unpublished ancestors')
 
-      # use 50 for group size, though maybe tune this depending on memory?
+      # use 25 for group size, though maybe tune this depending on memory?
       # build a list of objects with unpubbed ancestors
-      has_ancs.each_slice(50).with_index do |group,i|
+      has_ancs.each_slice(25).with_index do |group,i|
         if i % 400 == 0 && i != 0
           @job.write_output('Still checking for unpublished ancestors')
         end