Merge e9e43f5 into e3bb056

CHANGELOG.md

@@ -1,4 +1,8 @@
 # postgres-vacuum-monitor
+
+## v.0.8.0
+- Also report on queries that are being blocked by another process.
+
 ## v.0.7.0
 - Lower the default `LongTransactions` threshold from 1 hour to 5 minutes and make this configurable via
   the `long_running_transaction_threshold_seconds` setting.

lib/postgres/vacuum/jobs/monitor_job.rb

@@ -5,6 +5,7 @@ class MonitorJob
 
         AUTOVACUUM_LAGGING_EVENT = 'AutoVacuumLagging'.freeze
         LONG_TRANSACTIONS = 'LongTransactions'.freeze
+        BLOCKED_QUERIES = 'BlockedQueries'.freeze
 
         def perform(*)
           with_each_db_name_and_connection do |name, connection|
@@ -33,6 +34,17 @@ def perform(*)
                 tuples_over_limit: row['dead_tuples'].to_i - row['autovacuum_vacuum_tuples'].to_i
               )
             end
+
+            connection.execute(Postgres::Vacuum::Monitor::Query.blocked_queries).each do |row|
+              reporter_class.report_event(
+                BLOCKED_QUERIES,
+                database_name: name,
+                blocked_pid: row['blocked_pid'],
+                blocked_statement: row['blocked_statement'],
+                blocking_pid: row['blocking_pid'],
+                current_statement_in_blocking_process: row['current_statement_in_blocking_process']
+              )
+            end
           end
 
           true

lib/postgres/vacuum/monitor/query.rb

@@ -67,6 +67,36 @@ def tables_eligible_vacuuming
             ORDER BY  age(relfrozenxid) DESC LIMIT 50;
           SQL
         end
+
+        def blocked_queries
+          # The query was taken from https://wiki.postgresql.org/wiki/Lock_Monitoring
+          <<-SQL
+            SELECT blocked_locks.pid AS blocked_pid,
+              blocked_activity.usename AS blocked_user,
+              blocking_locks.pid AS blocking_pid,
+              blocking_activity.usename AS blocking_user,
+              blocked_activity.query AS blocked_statement,
+              blocking_activity.query AS current_statement_in_blocking_process,
+              blocked_activity.application_name AS blocked_application,
+              blocking_activity.application_name AS blocking_application
+            FROM pg_catalog.pg_locks blocked_locks
+            JOIN pg_catalog.pg_stat_activity blocked_activity  ON blocked_activity.pid = blocked_locks.pid
+            JOIN pg_catalog.pg_locks blocking_locks 
+              ON blocking_locks.locktype = blocked_locks.locktype
+              AND blocking_locks.DATABASE IS NOT DISTINCT FROM blocked_locks.DATABASE
+              AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation
+              AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page
+              AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple
+              AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid
+              AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid
+              AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid
+              AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid
+              AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid
+              AND blocking_locks.pid != blocked_locks.pid
+            JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
+            WHERE NOT blocked_locks.GRANTED;
+          SQL
+        end
       end
     end
   end

lib/postgres/vacuum/monitor/version.rb

@@ -1,7 +1,7 @@
 module Postgres
   module Vacuum
     module Monitor
-      VERSION = '0.7.0'.freeze
+      VERSION = '0.8.0'.freeze
     end
   end
 end

spec/postgres/vacuum/jobs/monitor_job_spec.rb

@@ -72,6 +72,28 @@ def self.report_event(name, attributes = {})
       )
     end
 
+    it "reports blocked queries" do
+      allow(mock_connection).to receive(:execute).with(Postgres::Vacuum::Monitor::Query.blocked_queries).and_return(
+        [
+          'blocked_pid' => 2,
+          'blocked_statement' => 'SELECT 1 FROM products',
+          'blocking_pid' => 3,
+          'current_statement_in_blocking_process' => 'SELECT 2 FROM products'
+        ]
+      )
+
+      job.perform
+
+      expect(TestMetricsReporter).to have_received(:report_event).with(
+        Postgres::Vacuum::Jobs::MonitorJob::BLOCKED_QUERIES,
+        database_name: 'postgres_vacuum_monitor_test',
+        blocked_pid: 2,
+        blocked_statement: 'SELECT 1 FROM products',
+        blocking_pid: 3,
+        current_statement_in_blocking_process: 'SELECT 2 FROM products'
+      )
+    end
+
     context "with multiple connection pools" do
 
       class SecondPool < ActiveRecord::Base
@@ -81,7 +103,7 @@ class SecondPool < ActiveRecord::Base
 
       it "reports once for a single database." do
         expect(job.perform).to eq true
-        expect(mock_connection).to have_received(:execute).twice
+        expect(mock_connection).to have_received(:execute).exactly(3)
       end
 
       context "to different databases" do
@@ -93,7 +115,7 @@ class SecondPool < ActiveRecord::Base
 
         it "reports twice for two databases" do
           expect(job.perform).to eq true
-          expect(mock_connection).to have_received(:execute).exactly(4)
+          expect(mock_connection).to have_received(:execute).exactly(6)
         end
       end
     end