tmp: reproduce bug from #258

.github/workflows/ci.yml

@@ -88,4 +88,4 @@ jobs:
           done
           cat ${{ github.workspace }}/setup.sql | cockroach sql --insecure
       - name: Test
-        run: bundle exec rake test TESTOPTS='--profile=5'
+        run: bundle exec rake test TESTOPTS='--profile=5 --name=test_concurrent_customer_insert_with_processes'

test/cases/transactions_test.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require "cases/helper_cockroachdb"
+
+module CockroachDB
+  class TransactionsTest < ActiveRecord::TestCase
+    class Customer < ActiveRecord::Base
+      validate :validate_unique_username
+
+      def validate_unique_username
+        duplicate = Customer.where(username: username).any?
+        errors.add("Duplicate username!") if duplicate
+      end
+
+      def to_s
+        "#{id}:#{name}:#{username}"
+      end
+    end
+
+    def setup
+      conn = ActiveRecord::Base.lease_connection
+      conn.create_table :customers, force: true do |t|
+        t.string :name
+        t.string :username
+      end
+    end
+
+    def teardown
+      conn = ActiveRecord::Base.lease_connection
+      conn.drop_table :customers, if_exists: true
+    end
+
+    def test_concurrent_customer_insert_with_processes
+      concurrency_level = 3
+      time_to_start = 2.seconds.from_now
+      pids = []
+
+      concurrency_level.times do |i|
+        pids << Process.fork do
+          sleep_time = (time_to_start - Time.current).to_f
+          sleep(sleep_time) if sleep_time > 0
+
+          begin
+            c = Customer.new
+            c.name = "Customer #{i + 1}"
+            c.username = SecureRandom.uuid
+            c.save!
+            puts "Inserted customer with id #{c.id} successfully!"
+          rescue => e
+            puts "Process #{Process.pid} - Error: #{e.message}"
+          end
+        end
+      end
+
+      pids.each { |pid| Process.wait(pid) }
+
+      puts "Customers #{Customer.all.map { |c| c.to_s }}"
+      assert_equal concurrency_level, Customer.count
+    end
+  end
+end