Merge pull request #16432 from CartoDB/bug/sc-246788/cc2-sync-failing-randomly-2

Log pg_locks when there is a timeout during a sync table importation

NEWS.md

@@ -97,6 +97,7 @@ Development
 - Fix error while rolling back a user migration from one cloud to another [#16421](https://github.com/CartoDB/cartodb/pull/16421)
 - Add retry if a timeout is thrown when swapping the tables related with a sync process [#16430](https://github.com/CartoDB/cartodb/pull/16430)
 - Add AUTODETECT_SIZE_LIMIT to ogr2ogr process when guessing CSV file column types [#16431](https://github.com/CartoDB/cartodb/pull/16431)
+- Log pg locks if there is any problem during a sync table import process [#16432](https://github.com/CartoDB/cartodb/pull/16432)
 
 4.45.0 (2021-04-14)
 -------------------

app/models/synchronization/adapter.rb

@@ -11,7 +11,7 @@ module CartoDB
       THE_GEOM = 'the_geom'.freeze
       OVERWRITE_ERROR = 2013
 
-      def initialize(table_name, runner, database, user, overviews_creator, synchronization_id)
+      def initialize(table_name, runner, database, user, overviews_creator, synchronization_id, logger = nil)
         @table_name   = table_name
         @runner       = runner
         @database     = database
@@ -25,6 +25,7 @@ module CartoDB
         )
         @error_code = nil
         @synchronization_id = synchronization_id
+        @logger = logger
       end
 
       def run(&tracker)
@@ -393,6 +394,18 @@ module CartoDB
         end
       rescue Exception => exception
         if exception.message.include?('canceling statement due to statement timeout')
+          # Check if the table has any lock
+          lock = user.in_database(as: :superuser).fetch(%Q{
+            SELECT pid, state, usename, query, query_start 
+            FROM pg_stat_activity 
+            WHERE pid in (
+              SELECT pid FROM pg_locks l 
+              JOIN pg_class t ON l.relation = t.oid 
+              AND t.relkind = 'r' 
+              WHERE t.relname IN ('#{table_name}')
+            );
+          }).first
+          @logger.append_and_store "Transaction timed out as the table is blocked by query #{lock[:query]}. Retrying in 60 seconds..." if @logger && lock.present?
           sleep(60) # wait 60 seconds and retry the swap
           database.transaction do
             rename(table_name, temporary_name) if exists?(table_name)

app/models/synchronization/member.rb

@@ -192,7 +192,7 @@ module CartoDB
 
         database = user.in_database
         overviews_creator = CartoDB::Importer2::Overviews.new(runner, user)
-        importer = CartoDB::Synchronization::Adapter.new(name, runner, database, user, overviews_creator, id)
+        importer = CartoDB::Synchronization::Adapter.new(name, runner, database, user, overviews_creator, id, @log)
 
         importer.run
         self.ran_at   = Time.now