v0.41 Further improve FULL concurrency support, for both MySQL/MariaDB _and_ importantly, the PostGreSQL Discourse DB additions and changes with ActiveRecord connection pooling and Mutex

gossamer_forums.rb

@@ -1,7 +1,7 @@
 # Federated Computer, Inc.
 # David Sainty <saint@federated.computer>  2024 A.D.
 # Gossamer Threads to Discourse -- Migration-Import Script
-# v0.40 Move to per thread MySQL/MariaDB connection
+# v0.41 Further improve FULL concurrency support, for both MySQL/MariaDB _and_ importantly, the PostGreSQL Discourse DB additions and changes with ActiveRecord connection pooling and Mutex
 
 require 'mysql2'
 require 'open-uri'
@@ -1072,16 +1072,20 @@ class GossamerForumsImporter < ImportScripts::Base
     current_post_batch = 0 # Set our current batch number. This tracks the current batch of posts being processed.
     is_complete = false # Flag to indicate whether the import process is complete.
 
+    # Mutex to control access to shared resources
+    mutex = Mutex.new
+
     # Run until all posts have been processed.
     until is_complete
       # Query in batches, create pool, wait for termination, do it again
       current_post_batch_max = current_post_batch + batch_size
 
 #      # Static pool size based on number of CPUs
-      # pool = Concurrent::FixedThreadPool.new(Concurrent.processor_count) #create thread pool that is bounded by processors avaialable, however play with the number to see what works best
+#      # pool = Concurrent::FixedThreadPool.new(Concurrent.processor_count) # Create a thread pool that is bounded by processors avaialable
+#      # pool = Concurrent::FixedThreadPool.new(8)                          # Create a thread pool of 8 pool members
 
       # Dynamically calculate the pool size based on system load to optimise performance
-      pool_size = calculate_dynamic_pool_size
+      pool_size = calculate_dynamic_pool_size            # Dynamically calculate what the pool size "ought" to be.
       pool = Concurrent::FixedThreadPool.new(pool_size)  # Create a thread pool with the calculated size
 
       # Process each post in the current batch
@@ -1102,6 +1106,10 @@ class GossamerForumsImporter < ImportScripts::Base
               password: "yxnh93Ybbz2Nm8#mp28zCVv",
               database: "slowtwitch"
             )
+
+            # Use connection ppoling for PostgreSQL and synchronize access to shared resources
+            ActiveRecord::Base.connection_pool.with_connection do
+              mutex.synchronize do
                 begin
                   puts "Processing post ID: #{post_id}"
                   topic_import_job(post_id, mysql_client)  # Import topic and its replies
@@ -1110,9 +1118,12 @@ class GossamerForumsImporter < ImportScripts::Base
                   puts "Error processing post ID #{post_id}: #{e.message}"
                   mark_post_as_failed(post_id)
                 ensure
+                  # Ensure the MariaDB connection is closed after processing
                   mysql_client.close if mysql_client
                 end
               end
+            end
+          end
         else
           puts "Skipping post_id #{post_id}, already processed."
         end
@@ -1172,6 +1183,7 @@ class GossamerForumsImporter < ImportScripts::Base
   
     # Check if the topic has already been imported using the custom field 'original_gossamer_id'
     unless TopicCustomField.exists?(name: 'original_gossamer_id', value: row['post_id'])
+      ActiveRecord::Base.transaction do
         # Create the new topic in Discourse
         begin
           suffix = 1
@@ -1243,7 +1255,7 @@ class GossamerForumsImporter < ImportScripts::Base
           new_url = "https://new/t/#{topic.slug}/#{topic.id}"
           insert_url_mapping(row['post_id'], new_url, unique_title)
     
-        # Now fetch and import all replies to this topic
+          # Fetch and import all replies to this topic
           replies = execute_query("SELECT post_id, user_id_fk, post_message, post_time, FROM gforum_Post WHERE post_root_id = #{post_id} ORDER BY post_time ASC")
     
           # Import each reply sequentially
@@ -1289,7 +1301,8 @@ class GossamerForumsImporter < ImportScripts::Base
 #             # Update the highest processed post_id in the database (thread-safe)
 #             update_highest_processed_post_id_thread_safe(reply_row['post_id'])
     
-          rescue ActiveRecord::RecordInvalid => e
+#            rescue ActiveRecord::RecordInvalid => e
+            rescue => e
               puts "Error importing reply with post_id #{reply_row['post_id']}: #{e.message}"
             end
           end
@@ -1299,8 +1312,12 @@ class GossamerForumsImporter < ImportScripts::Base
     
         rescue ActiveRecord::RecordInvalid => e
           puts "Error importing topic with post_id #{row['post_id']}: #{e.message}"
+          raise ActiveRecord::Rollback
         end
       end
+    else
+      puts "Topic for post_id #{row['post_id']} already exists, skipping creation."
+    end
   end