## A Multithreaded, Transaction-Based Locking Strategy for Containers Bob Steagall CppCon 2020 KEWB COMPUTING ## Overview • Sharing a container among multiple threads • A motivating problem • Some modification of an update group is treated as a single transaction, which either succeeds completely, or fails completely - Consistent: Each transaction can only bring the update group (and the enclosing enclosing container) from one valid state to another, maintaining all invariants - Isolated: Each transaction must ensure that concurrent execution of other transactions leaves its update group (and the container)

DataSourceTransactionManager closes JDBC connection on doBegin failure but leaves it attached to transaction object (SPR-12280) fixed webAsync responses force concurrentResult.toString() call (SPR-12253) fixed MBeanExportConfiguration.SpecificPlatform issue (SPR-11877) allow manually registered transaction manager to be recognized by qualifiedBeanOfType (SPR-11915) fixed misleading exception message attributes (SPR-9553) * JmsTemplate uses configured receiveTimeout if shorter than remaining transaction timeout (SPR-10109) * added MappingJackson2MessageConverter for JMS (SPR-10099) * JDBC parameter

well * fixed and updated reference documentation on JMS listener container configuration and transaction participation Package org.springframework.aop * Cglib2AopProxy uses weak references for advised the exception message * fixed Hibernate/JpaTransactionManager to clean up properly in case of transaction begin failure on pre-bound resource * revised JpaTransactionManager to convert JPA RollbackExceptions Creator's "joinTransaction()" checks whether there is an externally managed local transaction * ExtendedEntityManagerCreator's EntityManager proxies are serializable now $ ^{*} $ (

setExecutor method to correctly wrap in a TaskExecutorAdapter * @Transactional qualifiers match against transaction manager definitions in parent contexts as well * TransactionSynchronizationManager eagerly cleans r type * JmsResourceHolder does not ignore IllegalStateException from locally synchronized transaction * fixed JMS CachingConnectionFactory to correctly cache a producer without fixed destination as DefaultJdoDialect supports JDO 3.0 query timeout facility (as supported by DataNucleus 2.1) * transaction names based on method id from most specific method (target class instead of interface) * added

JobDetails in combination with autodetected JobDetailAwareTriggers Package org.springframework.transaction * fixed AbstractPlatformTransactionManager to always execute all synchronizations, even on unexpected JtaTransactionManager calls "afterCompletion" of Spring synchronizations at completion of outermost JTA transaction * JtaTransactionManager throws UnexpectedRollbackException in case of global rollback-only if default data access strategy to JDBC, to highlight the JMX export Package org.springframework.transaction * exposed "hasSavepoint" and "isCompleted" methods on TransactionStatus interface

exposes full * JmsResourceHolder does not ignore IllegalStateException from locally synchronized transaction * fixed JMS CachingConnectionFactory to correctly cache a producer without fixed destination as DefaultJdoDialect supports JDO 3.0 query timeout facility (as supported by DataNucleus 2.1) * transaction names based on method id from most specific method (target class instead of interface) * added Connection on demand (supporting aggressive release) * JCA listener containers delegate to wrapped Transaction handle (for Geronimo compatibility) * @Transactional qualifiers work in unit tests as well (T

"invokeGetterMethod" methods to ReflectionTestUtils Package org.springframework.transaction * transactional resource synchronization works even for operations triggered during commit (e allows for multi-line statements, each separated by a semicolon #### Package org.springframework.transaction * TransactionSynchronizationManager automatically unwraps InfrastructureProxy objects for raw concurrent transactions for different test methods (with timeout) Package org.springframework.transaction * "ClassUtils.resolveClassName" preserves the original root cause in the rethrown Ill

Bulk Inserts Transactions Context manager Decorator • Nesting Transactions • Explicit transaction • Autocommit Mode • Changes in 3.0 • Backwards-incompatible • New stuff • API so if the username is taken the database will raise an IntegrityError. try: with database.transaction(): # Attempt to create the user. If the username is taken, due to the unique constraint with duplicate rows: user = get_object_or_404(User, username=username) try: with database.transaction(): Relationship.create( from_user=get_current_user(), to_user=user)

"SpringTestContext" group anymore (for ease of using custom groups) Package org.springframework.transaction * added "validateExistingTransaction" property to AbstractPlatformTransactionManager, for throws TransactionSystemException in case of unexpected internal transaction state * JtaTransactionManager detects JBoss 4.2 transaction rollbacks caused by a timeout, throwing a meaningful exception * * fixed WebSphereUowTransactionManager to correctly detect an existing global transaction (ignoring local tx contexts) Package org.springframework.ui * fixed ModelMap's "mergeAttributes" to

el|You created an indirect dependency on uncommitted metadata. You must roll back the current transaction.| |-104|335544821|dsql\_column\_pos\_err|Invalid column position used in the @1 clause| |-104| repare\_err|Cannot prepare a CREATE DATABASE/SCHEMA statement| |-532|335544469|trans\_invalid|Transaction marked invalid by I/O error| |-551|335544352|no\_priv|No permission for @1 access to @2 @3| |---|---|---|---| type can't be changed| |-817|335544361|read\_only\_trans|Attempted update during read-only transaction| |-817|335544371|segstr\_no\_write|Attempted write to read-only BLOB| |-817|335544444|read\_only|Operation