Connection not available after exceptions with suspendable transaction

[prof18]

I've noticed that when an exception is thrown inside a newSuspendedTransaction, the database connection is not given back to the pool. So, after some exceptions are thrown the pool runs out of connections.

[HikariPool-1 housekeeper] DEBUG com.zaxxer.hikari.pool.HikariPool - 
HikariPool-1 - Pool stats (total=3, active=3, idle=0, waiting=2)

...

org.jetbrains.exposed.exceptions.ExposedSQLException: 
java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30001ms.

Instead, if I use a transaction, everything is fine and keeps working

[HikariPool-1 housekeeper] DEBUG com.zaxxer.hikari.pool.HikariPool - 
HikariPool-1 - Pool stats (total=3, active=0, idle=3, waiting=0)

It seems something similar to #1105

Here's the code:

fun Application.module(testing: Boolean = false) {
    setupDatabase()

    routing {

        get("/withTransaction") {
            transaction {
                User.new(1) {  }
            }
        }

        get("/withSuspendableTransaction") {
            newSuspendedTransaction {
                User.new(1) {  }
            }
        }
    }
}

fun setupDatabase() {
    val config = HikariConfig()
    config.driverClassName = "com.mysql.cj.jdbc.Driver"
    config.jdbcUrl = "jdbc:mysql://localhost:3307/test"
    config.username = "root"
    config.password = "password"
    config.maximumPoolSize = 3
    config.isAutoCommit = false
    config.transactionIsolation = "TRANSACTION_REPEATABLE_READ"

    // Suggestions from https://github.com/brettwooldridge/HikariCP/wiki/MySQL-Configuration
    config.addDataSourceProperty("cachePrepStmts", "true");
    config.addDataSourceProperty("prepStmtCacheSize", "250");
    config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
    config.addDataSourceProperty("useServerPrepStmts", "true");
    config.addDataSourceProperty("useLocalSessionState", "true");
    config.addDataSourceProperty("rewriteBatchedStatements", "true");
    config.addDataSourceProperty("cacheResultSetMetadata", "true");
    config.addDataSourceProperty("cacheServerConfiguration", "true");
    config.addDataSourceProperty("elideSetAutoCommits", "true");
    config.addDataSourceProperty("maintainTimeStats", "false");

    config.validate()
    val ds = HikariDataSource(config)
    Database.connect(ds)
}

object UserTable : IntIdTable(name = "table_name")

class User(id: EntityID<Int>) : IntEntity(id) {
    companion object : IntEntityClass<User>(UserTable)
}

[prof18]

I've pushed a sample project that replicates the issue: https://github.com/prof18/exposed-suspendable-issue

[Tapac]

Thank you for the sample it helps a lot. Should be fixed in master.

[prof18]

Perfect, thank you!