debug

spec/activerecord/debug_errors/ext/connection_adapters/abstract_mysql_adapter_spec.rb

@@ -71,17 +71,23 @@ def cause_deadlock(role:)
     context "when ActiveRecord::LockWaitTimeout occurs" do
       it "displays transactions and processlist" do
         barrier = CyclicBarrier.new(2)
-
+        logger = Logger.new($stderr)
         ths = Array.new(2) do
           Thread.new do
             User.transaction do
               barrier.await(1)
+              logger.info("#{Thread.current.object_id}: #{User.connection.execute("show variables like 'innodb_lock_wait_timeout'").to_a.first.join('=')}")
+              logger.info("#{Thread.current.object_id}: User.lock.find_by!")
               User.lock.find_by!(name: 'foo')
               sleep 2
+              logger.info("#{Thread.current.object_id}: done")
             end
           end
         end
 
+        ths.each.with_index do |th, i|
+          logger.info("ths[#{i}].object_id = #{th.object_id}")
+        end
         expect {
           ths.each(&:join)
         }.to raise_error(ActiveRecord::LockWaitTimeout)