Reduce chances to hit mysql2 execute with prepared statements bug

By decreasing the amount of cycles performed in this test we can avoid
whatever is causing this type of flake:

```
/home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:323:in `expire': Cannot expire connection, it is not currently leased. (ActiveRecord::ActiveRecordError)
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:572:in `block (3 levels) in checkin'
        from /home/zzak/code/rails/activesupport/lib/active_support/callbacks.rb:109:in `run_callbacks'
        from /home/zzak/code/rails/activesupport/lib/active_support/callbacks.rb:912:in `_run_checkin_callbacks'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `block (2 levels) in checkin'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `synchronize'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `mon_synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:568:in `block in checkin'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:567:in `checkin'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:384:in `release_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:415:in `ensure in with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:415:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_handling.rb:310:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:277:in `_update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:622:in `update_columns'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `block in decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:40:in `with_encryption_context'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:50:in `without_encryption'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:172:in `decrypt'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:22:in `block (2 levels) in thread_encrypting_and_decrypting'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `each'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `with_index'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'
/home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `_execute': Mysql2::Error: Mysql2::Error: `UPDATE `posts` SET `posts`.`title` = ?, `posts`.`body` = ? WHERE `posts`.`id` = ?` Bind parameter count (0) doesn't match number of arguments (3) (ActiveRecord::StatementInvalid)
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `block in execute'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `handle_interrupt'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/mysql2/database_statements.rb:71:in `block in perform_query'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/share_lock.rb:186:in `yield_shares'
        from /home/zzak/code/rails/activesupport/lib/active_support/dependencies/interlock.rb:41:in `permit_concurrent_loads'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/mysql2/database_statements.rb:70:in `perform_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:556:in `block (2 levels) in raw_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:1011:in `block in with_raw_connection'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:983:in `with_raw_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:555:in `block in raw_execute'
        from /home/zzak/code/rails/activesupport/lib/active_support/notifications/instrumenter.rb:58:in `instrument'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:1129:in `log'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:554:in `raw_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:591:in `internal_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:173:in `exec_update'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:208:in `update'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:27:in `update'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:278:in `block in _update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:412:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_handling.rb:310:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:277:in `_update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:622:in `update_columns'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `block in decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:40:in `with_encryption_context'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:50:in `without_encryption'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:172:in `decrypt'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:22:in `block (2 levels) in thread_encrypting_and_decrypting'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `each'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `with_index'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'
/home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `_execute': Mysql2::Error: `UPDATE `posts` SET `posts`.`title` = ?, `posts`.`body` = ? WHERE `posts`.`id` = ?` Bind parameter count (0) doesn't match number of arguments (3) (Mysql2::Error)
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `block in execute'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `handle_interrupt'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/mysql2/database_statements.rb:71:in `block in perform_query'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/share_lock.rb:186:in `yield_shares'
        from /home/zzak/code/rails/activesupport/lib/active_support/dependencies/interlock.rb:41:in `permit_concurrent_loads'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/mysql2/database_statements.rb:70:in `perform_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:556:in `block (2 levels) in raw_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:1011:in `block in with_raw_connection'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:983:in `with_raw_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:555:in `block in raw_execute'
        from /home/zzak/code/rails/activesupport/lib/active_support/notifications/instrumenter.rb:58:in `instrument'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:1129:in `log'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:554:in `raw_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:591:in `internal_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:173:in `exec_update'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:208:in `update'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:27:in `update'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:278:in `block in _update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:412:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_handling.rb:310:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:277:in `_update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:622:in `update_columns'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `block in decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:40:in `with_encryption_context'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:50:in `without_encryption'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:172:in `decrypt'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:22:in `block (2 levels) in thread_encrypting_and_decrypting'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `each'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `with_index'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'
/home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `_execute': Bind parameter count (0) doesn't match number of arguments (3) (Mysql2::Error)
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `block in execute'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `handle_interrupt'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/mysql2/database_statements.rb:71:in `block in perform_query'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/share_lock.rb:186:in `yield_shares'
        from /home/zzak/code/rails/activesupport/lib/active_support/dependencies/interlock.rb:41:in `permit_concurrent_loads'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/mysql2/database_statements.rb:70:in `perform_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:556:in `block (2 levels) in raw_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:1011:in `block in with_raw_connection'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:983:in `with_raw_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:555:in `block in raw_execute'
        from /home/zzak/code/rails/activesupport/lib/active_support/notifications/instrumenter.rb:58:in `instrument'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:1129:in `log'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:554:in `raw_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:591:in `internal_execute'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:173:in `exec_update'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:208:in `update'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:27:in `update'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:278:in `block in _update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:412:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_handling.rb:310:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:277:in `_update_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:622:in `update_columns'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `block in decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:40:in `with_encryption_context'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/contexts.rb:50:in `without_encryption'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:197:in `decrypt_attributes'
        from /home/zzak/code/rails/activerecord/lib/active_record/encryption/encryptable_record.rb:172:in `decrypt'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:22:in `block (2 levels) in thread_encrypting_and_decrypting'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `each'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `with_index'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'
E

Error:
ActiveRecord::Encryption::ConcurrencyTest#test_models_can_be_encrypted_and_decrypted_in_different_threads_concurrently:
ActiveRecord::StatementInvalid: Mysql2::Error: Mysql2::Error: `SELECT `posts`.* FROM `posts` WHERE `posts`.`type` = ? ORDER BY `posts`.`id` DESC LIMIT ?` Commands out of sync; you can't run this command now
    /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `_execute'
    /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:5:in `block in execute'
    /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `handle_interrupt'
    /home/zzak/.rbenv/versions/3.2.3/lib/ruby/gems/3.2.0/gems/mysql2-0.5.6/lib/mysql2/statement.rb:4:in `execute'
    lib/active_record/connection_adapters/mysql2/database_statements.rb:71:in `block in perform_query'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/share_lock.rb:186:in `yield_shares'
    /home/zzak/code/rails/activesupport/lib/active_support/dependencies/interlock.rb:41:in `permit_concurrent_loads'
    lib/active_record/connection_adapters/mysql2/database_statements.rb:70:in `perform_query'
    lib/active_record/connection_adapters/abstract/database_statements.rb:556:in `block (2 levels) in raw_execute'
    lib/active_record/connection_adapters/abstract_adapter.rb:1011:in `block in with_raw_connection'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
    lib/active_record/connection_adapters/abstract_adapter.rb:983:in `with_raw_connection'
    lib/active_record/connection_adapters/abstract/database_statements.rb:555:in `block in raw_execute'
    /home/zzak/code/rails/activesupport/lib/active_support/notifications/instrumenter.rb:58:in `instrument'
    lib/active_record/connection_adapters/abstract_adapter.rb:1129:in `log'
    lib/active_record/connection_adapters/abstract/database_statements.rb:554:in `raw_execute'
    lib/active_record/connection_adapters/abstract/database_statements.rb:591:in `internal_execute'
    lib/active_record/connection_adapters/abstract/database_statements.rb:547:in `internal_exec_query'
    lib/active_record/connection_adapters/abstract/database_statements.rb:693:in `select'
    lib/active_record/connection_adapters/abstract/database_statements.rb:73:in `select_all'
    lib/active_record/connection_adapters/abstract/query_cache.rb:251:in `select_all'
    lib/active_record/connection_adapters/mysql2/database_statements.rb:12:in `select_all'
    lib/active_record/querying.rb:68:in `_query_by_sql'
    lib/active_record/relation.rb:1449:in `block (2 levels) in exec_main_query'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:406:in `with_connection'
    lib/active_record/connection_handling.rb:310:in `with_connection'
    lib/active_record/relation.rb:1448:in `block in exec_main_query'
    lib/active_record/relation.rb:1470:in `skip_query_cache_if_necessary'
    lib/active_record/relation.rb:1432:in `exec_main_query'
    lib/active_record/relation.rb:1410:in `block in exec_queries'
    lib/active_record/relation.rb:1470:in `skip_query_cache_if_necessary'
    lib/active_record/relation.rb:1404:in `exec_queries'
    lib/active_record/relation.rb:1181:in `load'
    lib/active_record/relation.rb:343:in `records'
    lib/active_record/relation/delegation.rb:101:in `reverse'
    lib/active_record/relation/finder_methods.rb:208:in `last'
    lib/active_record/querying.rb:24:in `last'
    test/cases/encryption/concurrency_test.rb:17:in `thread_encrypting_and_decrypting'
    test/cases/encryption/concurrency_test.rb:12:in `block (2 levels) in <class:ConcurrencyTest>'
    test/cases/encryption/concurrency_test.rb:12:in `times'
    test/cases/encryption/concurrency_test.rb:12:in `each'
    test/cases/encryption/concurrency_test.rb:12:in `collect'
    test/cases/encryption/concurrency_test.rb:12:in `block in <class:ConcurrencyTest>'

Error:
ActiveRecord::Encryption::ConcurrencyTest#test_models_can_be_encrypted_and_decrypted_in_different_threads_concurrently:
ActiveRecord::ActiveRecordError: Cannot expire connection, it is not currently leased.
    lib/active_record/connection_adapters/abstract_adapter.rb:323:in `expire'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:572:in `block (3 levels) in checkin'
    /home/zzak/code/rails/activesupport/lib/active_support/callbacks.rb:109:in `run_callbacks'
    /home/zzak/code/rails/activesupport/lib/active_support/callbacks.rb:912:in `_run_checkin_callbacks'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `block (2 levels) in checkin'
    /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `synchronize'
    /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `mon_synchronize'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:568:in `block in checkin'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
    /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:567:in `checkin'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:384:in `release_connection'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:415:in `ensure in with_connection'
    lib/active_record/connection_adapters/abstract/connection_pool.rb:415:in `with_connection'
    lib/active_record/connection_handling.rb:310:in `with_connection'
    lib/active_record/persistence.rb:277:in `_update_record'
    lib/active_record/persistence.rb:622:in `update_columns'
    lib/active_record/encryption/encryptable_record.rb:197:in `block in decrypt_attributes'
    lib/active_record/encryption/contexts.rb:40:in `with_encryption_context'
    lib/active_record/encryption/contexts.rb:50:in `without_encryption'
    lib/active_record/encryption/encryptable_record.rb:197:in `decrypt_attributes'
    lib/active_record/encryption/encryptable_record.rb:172:in `decrypt'
    test/cases/encryption/concurrency_test.rb:22:in `block (2 levels) in thread_encrypting_and_decrypting'
    test/cases/encryption/concurrency_test.rb:20:in `each'
    test/cases/encryption/concurrency_test.rb:20:in `with_index'
    test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'

/home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:545:in `block (2 levels) in checkout': undefined method `verify!' for nil:NilClass (NoMethodError)

              @pinned_connection.verify!
                                ^^^^^^^^
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `synchronize'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `mon_synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:544:in `block in checkout'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:543:in `checkout'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:412:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_handling.rb:310:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1448:in `block in exec_main_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1470:in `skip_query_cache_if_necessary'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1432:in `exec_main_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1410:in `block in exec_queries'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1470:in `skip_query_cache_if_necessary'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1404:in `exec_queries'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1181:in `load'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:343:in `records'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:586:in `find_take'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:129:in `take'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:135:in `take!'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:118:in `find_by!'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:834:in `_find_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:749:in `block in reload'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1373:in `_scoping'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:548:in `scoping'
        from /home/zzak/code/rails/activerecord/lib/active_record/scoping/default.rb:51:in `unscoped'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:749:in `reload'
        from /home/zzak/code/rails/activerecord/lib/active_record/attribute_methods/dirty.rb:64:in `reload'
        from /home/zzak/code/rails/activerecord/lib/active_record/autosave_association.rb:241:in `reload'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/helper.rb:22:in `assert_encrypted_attribute'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:21:in `block (2 levels) in thread_encrypting_and_decrypting'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `each'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `with_index'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'
/home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:545:in `block (2 levels) in checkout': undefined method `verify!' for nil:NilClass (NoMethodError)

              @pinned_connection.verify!
                                ^^^^^^^^
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `synchronize'
        from /home/zzak/.rbenv/versions/3.2.3/lib/ruby/3.2.0/monitor.rb:202:in `mon_synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:544:in `block in checkout'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:23:in `block in synchronize'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `handle_interrupt'
        from /home/zzak/code/rails/activesupport/lib/active_support/concurrency/load_interlock_aware_monitor.rb:19:in `synchronize'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:543:in `checkout'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:412:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/connection_handling.rb:310:in `with_connection'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1448:in `block in exec_main_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1470:in `skip_query_cache_if_necessary'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1432:in `exec_main_query'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1410:in `block in exec_queries'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1470:in `skip_query_cache_if_necessary'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1404:in `exec_queries'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1181:in `load'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:343:in `records'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:586:in `find_take'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:129:in `take'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:135:in `take!'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation/finder_methods.rb:118:in `find_by!'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:834:in `_find_record'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:749:in `block in reload'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:1373:in `_scoping'
        from /home/zzak/code/rails/activerecord/lib/active_record/relation.rb:548:in `scoping'
        from /home/zzak/code/rails/activerecord/lib/active_record/scoping/default.rb:51:in `unscoped'
        from /home/zzak/code/rails/activerecord/lib/active_record/persistence.rb:749:in `reload'
        from /home/zzak/code/rails/activerecord/lib/active_record/attribute_methods/dirty.rb:64:in `reload'
        from /home/zzak/code/rails/activerecord/lib/active_record/autosave_association.rb:241:in `reload'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/helper.rb:22:in `assert_encrypted_attribute'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:21:in `block (2 levels) in thread_encrypting_and_decrypting'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `each'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `with_index'
        from /home/zzak/code/rails/activerecord/test/cases/encryption/concurrency_test.rb:20:in `block in thread_encrypting_and_decrypting'
```

Author: zzak

activerecord/test/cases/encryption/concurrency_test.rb

@@ -9,12 +9,12 @@ class ActiveRecord::Encryption::ConcurrencyTest < ActiveRecord::EncryptionTestCa
   end
 
   test "models can be encrypted and decrypted in different threads concurrently" do
-    4.times.collect { |index| thread_encrypting_and_decrypting("thread #{index}") }.each(&:join)
+    3.times.collect { |index| thread_encrypting_and_decrypting("thread #{index}") }.each(&:join)
   end
 
   def thread_encrypting_and_decrypting(thread_label)
-    EncryptedPost.insert_all 100.times.collect { |index| { title: "Article #{index} (#{thread_label})", body: "Body #{index} (#{thread_label})" } }
-    posts = EncryptedPost.last(100)
+    EncryptedPost.insert_all 10.times.collect { |index| { title: "Article #{index} (#{thread_label})", body: "Body #{index} (#{thread_label})" } }
+    posts = EncryptedPost.last(10)
 
     Thread.new do
       posts.each.with_index do |article, index|