Merge branch '36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout' into 'master'

Insert at most 1,000 rows at once in MR diff background migration

Closes #36631 et #37505

See merge request gitlab-org/gitlab-ce!13661

5 files changed, 226 insertions, 25 deletions

diff --git a/changelogs/unreleased/36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml b/changelogs/unreleased/36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml
new file mode 100644
index 00000000000..a2e1d07158b
--- /dev/null
+++ b/changelogs/unreleased/36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml
@@ -0,0 +1,6 @@
+---
+title: Reschedule merge request diff background migrations to catch failures from
+  9.5 run
+merge_request:
+author:
+type: fixed
diff --git a/db/post_migrate/20170926150348_schedule_merge_request_diff_migrations_take_two.rb b/db/post_migrate/20170926150348_schedule_merge_request_diff_migrations_take_two.rb
new file mode 100644
index 00000000000..5732cb85ea5
--- /dev/null
+++ b/db/post_migrate/20170926150348_schedule_merge_request_diff_migrations_take_two.rb
@@ -0,0 +1,32 @@
+class ScheduleMergeRequestDiffMigrationsTakeTwo < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  BATCH_SIZE = 500
+  MIGRATION = 'DeserializeMergeRequestDiffsAndCommits'
+  DELAY_INTERVAL = 10.minutes
+
+  disable_ddl_transaction!
+
+  class MergeRequestDiff < ActiveRecord::Base
+    self.table_name = 'merge_request_diffs'
+
+    include ::EachBatch
+
+    default_scope { where('st_commits IS NOT NULL OR st_diffs IS NOT NULL') }
+  end
+
+  # By this point, we assume ScheduleMergeRequestDiffMigrations - the first
+  # version of this - has already run. On GitLab.com, we have ~220k un-migrated
+  # rows, but these rows will, in general, take a long time.
+  #
+  # With a gap of 10 minutes per batch, and 500 rows per batch, these migrations
+  # are scheduled over 220_000 / 500 / 6 ~= 74 hours, which is a little over
+  # three days.
+  def up
+    queue_background_migration_jobs_by_range_at_intervals(MergeRequestDiff, MIGRATION, DELAY_INTERVAL, batch_size: BATCH_SIZE)
+  end
+
+  def down
+  end
+end
diff --git a/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb b/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb
index 3fde1b09efb..8e5c95f2287 100644
--- a/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb
+++ b/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb
@@ -3,11 +3,18 @@ module Gitlab
     class DeserializeMergeRequestDiffsAndCommits
       attr_reader :diff_ids, :commit_rows, :file_rows
 
+      class Error < StandardError
+        def backtrace
+          cause.backtrace
+        end
+      end
+
       class MergeRequestDiff < ActiveRecord::Base
         self.table_name = 'merge_request_diffs'
       end
 
       BUFFER_ROWS = 1000
+      DIFF_FILE_BUFFER_ROWS = 100
 
       def perform(start_id, stop_id)
         merge_request_diffs = MergeRequestDiff
@@ -26,13 +33,17 @@ module Gitlab
 
           if diff_ids.length > BUFFER_ROWS ||
               commit_rows.length > BUFFER_ROWS ||
-              file_rows.length > BUFFER_ROWS
+              file_rows.length > DIFF_FILE_BUFFER_ROWS
 
             flush_buffers!
           end
         end
 
         flush_buffers!
+      rescue => e
+        Rails.logger.info("#{self.class.name}: failed for IDs #{merge_request_diffs.map(&:id)} with #{e.class.name}")
+
+        raise Error.new(e.inspect)
       end
 
       private
@@ -45,17 +56,28 @@ module Gitlab
 
       def flush_buffers!
         if diff_ids.any?
-          MergeRequestDiff.transaction do
-            Gitlab::Database.bulk_insert('merge_request_diff_commits', commit_rows)
-            Gitlab::Database.bulk_insert('merge_request_diff_files', file_rows)
+          commit_rows.each_slice(BUFFER_ROWS).each do |commit_rows_slice|
+            bulk_insert('merge_request_diff_commits', commit_rows_slice)
+          end
 
-            MergeRequestDiff.where(id: diff_ids).update_all(st_commits: nil, st_diffs: nil)
+          file_rows.each_slice(DIFF_FILE_BUFFER_ROWS).each do |file_rows_slice|
+            bulk_insert('merge_request_diff_files', file_rows_slice)
           end
+
+          MergeRequestDiff.where(id: diff_ids).update_all(st_commits: nil, st_diffs: nil)
         end
 
         reset_buffers!
       end
 
+      def bulk_insert(table, rows)
+        Gitlab::Database.bulk_insert(table, rows)
+      rescue ActiveRecord::RecordNotUnique
+        ids = rows.map { |row| row[:merge_request_diff_id] }.uniq.sort
+
+        Rails.logger.info("#{self.class.name}: rows inserted twice for IDs #{ids}")
+      end
+
       def single_diff_rows(merge_request_diff)
         sha_attribute = Gitlab::Database::ShaAttribute.new
         commits = YAML.load(merge_request_diff.st_commits) rescue []
diff --git a/spec/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits_spec.rb b/spec/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits_spec.rb
index c0427639746..d2e7243ee05 100644
--- a/spec/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits_spec.rb
+++ b/spec/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits_spec.rb
@@ -1,9 +1,9 @@
 require 'spec_helper'
 
-describe Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits do
+describe Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits, :truncate do
   describe '#perform' do
-    set(:merge_request) { create(:merge_request) }
-    set(:merge_request_diff) { merge_request.merge_request_diff }
+    let(:merge_request) { create(:merge_request) }
+    let(:merge_request_diff) { merge_request.merge_request_diff }
     let(:updated_merge_request_diff) { MergeRequestDiff.find(merge_request_diff.id) }
 
     def diffs_to_hashes(diffs)
@@ -70,8 +70,8 @@ describe Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits do
       before do
         merge_request.reload_diff(true)
 
-        convert_to_yaml(start_id, merge_request_diff.commits, merge_request_diff.diffs)
-        convert_to_yaml(stop_id, updated_merge_request_diff.commits, updated_merge_request_diff.diffs)
+        convert_to_yaml(start_id, merge_request_diff.commits, diffs_to_hashes(merge_request_diff.merge_request_diff_files))
+        convert_to_yaml(stop_id, updated_merge_request_diff.commits, diffs_to_hashes(updated_merge_request_diff.merge_request_diff_files))
 
         MergeRequestDiffCommit.delete_all
         MergeRequestDiffFile.delete_all
@@ -80,10 +80,32 @@ describe Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits do
       context 'when BUFFER_ROWS is exceeded' do
         before do
           stub_const("#{described_class}::BUFFER_ROWS", 1)
+
+          allow(Gitlab::Database).to receive(:bulk_insert).and_call_original
+        end
+
+        it 'inserts commit rows in chunks of BUFFER_ROWS' do
+          # There are 29 commits in each diff, so we should have slices of 20 + 9 + 20 + 9.
+          stub_const("#{described_class}::BUFFER_ROWS", 20)
+
+          expect(Gitlab::Database).to receive(:bulk_insert)
+                                        .with('merge_request_diff_commits', anything)
+                                        .exactly(4)
+                                        .times
+                                        .and_call_original
+
+          subject.perform(start_id, stop_id)
         end
 
-        it 'updates and continues' do
-          expect(described_class::MergeRequestDiff).to receive(:transaction).twice
+        it 'inserts diff rows in chunks of DIFF_FILE_BUFFER_ROWS' do
+          # There are 20 files in each diff, so we should have slices of 20 + 20.
+          stub_const("#{described_class}::DIFF_FILE_BUFFER_ROWS", 20)
+
+          expect(Gitlab::Database).to receive(:bulk_insert)
+                                        .with('merge_request_diff_files', anything)
+                                        .exactly(2)
+                                        .times
+                                        .and_call_original
 
           subject.perform(start_id, stop_id)
         end
@@ -91,27 +113,87 @@ describe Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits do
 
       context 'when BUFFER_ROWS is not exceeded' do
         it 'only updates once' do
-          expect(described_class::MergeRequestDiff).to receive(:transaction).once
+          expect(Gitlab::Database).to receive(:bulk_insert)
+                                        .with('merge_request_diff_commits', anything)
+                                        .once
+                                        .and_call_original
+
+          expect(Gitlab::Database).to receive(:bulk_insert)
+                                        .with('merge_request_diff_files', anything)
+                                        .once
+                                        .and_call_original
 
           subject.perform(start_id, stop_id)
         end
       end
-    end
 
-    context 'when the merge request diff update fails' do
-      before do
-        allow(described_class::MergeRequestDiff)
-          .to receive(:update_all).and_raise(ActiveRecord::Rollback)
-      end
+      context 'when some rows were already inserted due to a previous failure' do
+        before do
+          subject.perform(start_id, stop_id)
 
-      it 'does not add any diff commits' do
-        expect { subject.perform(merge_request_diff.id, merge_request_diff.id) }
-          .not_to change { MergeRequestDiffCommit.count }
+          convert_to_yaml(start_id, merge_request_diff.commits, diffs_to_hashes(merge_request_diff.merge_request_diff_files))
+          convert_to_yaml(stop_id, updated_merge_request_diff.commits, diffs_to_hashes(updated_merge_request_diff.merge_request_diff_files))
+        end
+
+        it 'does not raise' do
+          expect { subject.perform(start_id, stop_id) }.not_to raise_exception
+        end
+
+        it 'logs a message' do
+          expect(Rails.logger).to receive(:info)
+                                    .with(
+                                      a_string_matching(described_class.name).and(matching([start_id, stop_id].inspect))
+                                    )
+                                    .twice
+
+          subject.perform(start_id, stop_id)
+        end
+
+        it 'ends up with the correct rows' do
+          expect(updated_merge_request_diff.commits.count).to eq(29)
+          expect(updated_merge_request_diff.raw_diffs.count).to eq(20)
+        end
       end
 
-      it 'does not add any diff files' do
-        expect { subject.perform(merge_request_diff.id, merge_request_diff.id) }
-          .not_to change { MergeRequestDiffFile.count }
+      context 'when the merge request diff update fails' do
+        let(:exception) { ActiveRecord::RecordNotFound }
+
+        let(:perform_ignoring_exceptions) do
+          begin
+            subject.perform(start_id, stop_id)
+          rescue described_class::Error
+          end
+        end
+
+        before do
+          allow_any_instance_of(described_class::MergeRequestDiff::ActiveRecord_Relation)
+            .to receive(:update_all).and_raise(exception)
+        end
+
+        it 'raises an error' do
+          expect { subject.perform(start_id, stop_id) }
+            .to raise_exception(described_class::Error)
+        end
+
+        it 'logs the error' do
+          expect(Rails.logger).to receive(:info).with(
+            a_string_matching(described_class.name)
+              .and(matching([start_id, stop_id].inspect))
+              .and(matching(exception.name))
+          )
+
+          perform_ignoring_exceptions
+        end
+
+        it 'still adds diff commits' do
+          expect { perform_ignoring_exceptions }
+            .to change { MergeRequestDiffCommit.count }
+        end
+
+        it 'still adds diff files' do
+          expect { perform_ignoring_exceptions }
+            .to change { MergeRequestDiffFile.count }
+        end
       end
     end
 
diff --git a/spec/migrations/schedule_merge_request_diff_migrations_take_two_spec.rb b/spec/migrations/schedule_merge_request_diff_migrations_take_two_spec.rb
new file mode 100644
index 00000000000..4ab1bb67058
--- /dev/null
+++ b/spec/migrations/schedule_merge_request_diff_migrations_take_two_spec.rb
@@ -0,0 +1,59 @@
+require 'spec_helper'
+require Rails.root.join('db', 'post_migrate', '20170926150348_schedule_merge_request_diff_migrations_take_two')
+
+describe ScheduleMergeRequestDiffMigrationsTakeTwo, :migration, :sidekiq do
+  matcher :be_scheduled_migration do |time, *expected|
+    match do |migration|
+      BackgroundMigrationWorker.jobs.any? do |job|
+        job['args'] == [migration, expected] &&
+          job['at'].to_i == time.to_i
+      end
+    end
+
+    failure_message do |migration|
+      "Migration `#{migration}` with args `#{expected.inspect}` not scheduled!"
+    end
+  end
+
+  let(:merge_request_diffs) { table(:merge_request_diffs) }
+  let(:merge_requests) { table(:merge_requests) }
+  let(:projects) { table(:projects) }
+
+  before do
+    stub_const("#{described_class.name}::BATCH_SIZE", 1)
+
+    projects.create!(id: 1, name: 'gitlab', path: 'gitlab')
+
+    merge_requests.create!(id: 1, target_project_id: 1, source_project_id: 1, target_branch: 'feature', source_branch: 'master')
+
+    merge_request_diffs.create!(id: 1, merge_request_id: 1, st_commits: YAML.dump([]), st_diffs: nil)
+    merge_request_diffs.create!(id: 2, merge_request_id: 1, st_commits: nil, st_diffs: YAML.dump([]))
+    merge_request_diffs.create!(id: 3, merge_request_id: 1, st_commits: nil, st_diffs: nil)
+    merge_request_diffs.create!(id: 4, merge_request_id: 1, st_commits: YAML.dump([]), st_diffs: YAML.dump([]))
+  end
+
+  it 'correctly schedules background migrations' do
+    Sidekiq::Testing.fake! do
+      Timecop.freeze do
+        migrate!
+
+        expect(described_class::MIGRATION).to be_scheduled_migration(10.minutes.from_now, 1, 1)
+        expect(described_class::MIGRATION).to be_scheduled_migration(20.minutes.from_now, 2, 2)
+        expect(described_class::MIGRATION).to be_scheduled_migration(30.minutes.from_now, 4, 4)
+        expect(BackgroundMigrationWorker.jobs.size).to eq 3
+      end
+    end
+  end
+
+  it 'migrates the data' do
+    Sidekiq::Testing.inline! do
+      non_empty = 'st_commits IS NOT NULL OR st_diffs IS NOT NULL'
+
+      expect(merge_request_diffs.where(non_empty).count).to eq 3
+
+      migrate!
+
+      expect(merge_request_diffs.where(non_empty).count).to eq 0
+    end
+  end
+end