Connection leak.

Hello, I’m is using some spring libraries, that call queries via jdbcTemplate and transactionTemplate. I have encountered a problem. If exposed transactions are used with Spring transactionTemplate there is a connection leak.

Issue project: https://github.com/neetkee/exposed-jdbc-template-demo. You can just run tests to reproduce the problem. Error:

Could not open JDBC Connection for transaction; nested exception is java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30005ms.
org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30005ms.
	at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:309)
	at org.jetbrains.exposed.spring.SpringTransactionManager.doBegin(SpringTransactionManager.kt:41)
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.startTransaction(AbstractPlatformTransactionManager.java:400)
	at
Omitted

[Tapac]

@neetkee , thank you very much for providing such a complex sample. Looks like I was able to debug and fix that tricky case. I copy-pasted your test-sample into Exposed project. I will try to release the fix by the end of the week

[AleksanderBrzozowski]

We had the same issue in our project, everything worked for a small load, but when we did performance tests, connection leaks started to occur.

We have created something like this to fix this:

// this class is exposed as a bean
class TransactionOperations(datasource: Datasource) {
    private val db = Database.connect(datasource)
    
    operator fun <T> invoke(block: () -> T): T {
        //exposed transaction
        return transaction(..., db = db) { callback() }
    }
}

Since you don’t use @Transactional annotation, you could try it to 😃