Failure while connecting to the H2 database after refreshing page with subscription query API for 10 times

Axon Framework
, ,
1

I’m using H2 DB and axon subscription queries for a REST API to stream a list of books that are added to a library. After refreshing the streaming endpoint for about 10 times, it fails with error:

Can you please help?

org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
Caused by: java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out

Below is a complete stack trace and my axon configuration which uses in memory event store. I’m using spring boot so have not customized any data source configuration and using out of the box configuration
for JDBC connection .

Subscription query uses QueryUpdateEmitter to emit the new books in the @eventHandler for NewBookCreatedEvent and uses subscription query for REST API.

Here’s my axon configuration:

// Simple command bus using Spring’s PlatformTransactionManager

@Bean
public CommandBus commandBus(PlatformTransactionManager platformTransactionManager) {
    return SimpleCommandBus.builder()
            .transactionManager(new SpringTransactionManager(platformTransactionManager))
            .build();
}

/**
 * The Event store `EmbeddedEventStore` delegates actual storage and retrieval of events to an `EventStorageEngine`.
 */
@Bean
public EmbeddedEventStore eventStore(EventStorageEngine storageEngine, AxonConfiguration configuration) {
    return EmbeddedEventStore.builder()
            .storageEngine(storageEngine)
            .messageMonitor(configuration.messageMonitor(EventStore.class, "eventStore"))
            .build();
}

// The `InMemoryEventStorageEngine` stores each event in memory
@Bean
public EventStorageEngine storageEngine() {
    return new InMemoryEventStorageEngine();
}

@Bean
public SimpleQueryBus queryBus(AxonConfiguration axonConfiguration, TransactionManager transactionManager) {
    return SimpleQueryBus.builder()
            .messageMonitor(axonConfiguration.messageMonitor(QueryBus.class, "queryBus"))
            .transactionManager(transactionManager)
            .errorHandler(axonConfiguration.getComponent(
                    QueryInvocationErrorHandler.class,
                    () -> LoggingQueryInvocationErrorHandler.builder().build()
            ))
            .queryUpdateEmitter(axonConfiguration.getComponent(QueryUpdateEmitter.class))
            .build();
}

Exception:

org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:467) ~[spring-orm-5.3.9.jar:5.3.9]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.startTransaction(AbstractPlatformTransactionManager.java:400) ~[spring-tx-5.3.9.jar:5.3.9]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373) ~[spring-tx-5.3.9.jar:5.3.9]
at org.axonframework.spring.messaging.unitofwork.SpringTransactionManager.startTransaction(SpringTransactionManager.java:59) ~[axon-spring-4.5.1.jar:4.5.1]
at org.axonframework.common.transaction.TransactionManager.executeInTransaction(TransactionManager.java:45) ~[axon-messaging-4.5.1.jar:4.5.1]
at org.axonframework.eventhandling.TrackingEventProcessor.processBatch(TrackingEventProcessor.java:417) ~[axon-messaging-4.5.1.jar:4.5.1]
at org.axonframework.eventhandling.TrackingEventProcessor.processingLoop(TrackingEventProcessor.java:283) ~[axon-messaging-4.5.1.jar:4.5.1]
at org.axonframework.eventhandling.TrackingEventProcessor$TrackingSegmentWorker.run(TrackingEventProcessor.java:993) ~[axon-messaging-4.5.1.jar:4.5.1]
at org.axonframework.eventhandling.TrackingEventProcessor$WorkerLauncher.run(TrackingEventProcessor.java:1132) ~[axon-messaging-4.5.1.jar:4.5.1]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
Caused by: org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:48) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:111) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:138) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getConnectionForTransactionManagement(LogicalConnectionManagedImpl.java:276) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:284) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:246) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:83) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:164) ~[spring-orm-5.3.9.jar:5.3.9]
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:421) ~[spring-orm-5.3.9.jar:5.3.9]
… 9 common frames omitted
Caused by: java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30001ms.
at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:696) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:197) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128) ~[HikariCP-4.0.3.jar:na]
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.internal.NonContextualJdbcConnectionAccess.obtainConnection(NonContextualJdbcConnectionAccess.java:38) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:108) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
… 16 common frames omitted

2

Can you please let me know if someone had chance to look into this?

3

Hello @payalshah,

10 is a too magic number to be just a coincidence!
It is probably the size of your database connection pool and somewhere those connections are not being closed.

Again, the same post I shared on a different post can help you which is exactly about terminating it server side!

If that doesn’t do the trick, we also had some problems before where the server wouldn’t know the client is not listening and would have to close the connection itself.

Let me know if the post can help you.
If not, let me know if you are able to monitor your connection pool to understand if that is the magical number and if the connections are never returned to the pool after you refresh the page.

KR,

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