Using forUpdate in suspended transaction causes deadlock

[satamas]

Reproducer:

fun main(args: Array<String>) {
    Database.connect(
        "jdbc:postgresql://localhost:54321/grazie",
        user = "admin",
        password = "admin",
        driver = "org.postgresql.Driver"
    )
    while (true) {
        try {
            runBlocking {
                repeat(2) {
                    launch {
                        newSuspendedTransaction {
                            val license = UserLicenseEntity.find { UserLicenseTable.id eq 1 }.forUpdate().singleOrNull()
                            println(license?.licenseType ?: "No license found")
                            delay(50)
                        }
                    }
                }
            }
        } catch (e: Exception) {
        }
    }
}

class UserLicenseEntity(id: EntityID<Int>) : IntEntity(id) {
    val licenseType by UserLicenseTable.license_type

    companion object : IntEntityClass<UserLicenseEntity>(UserLicenseTable)
}

object UserLicenseTable : IntIdTable("user_license") {
    val license_type = text("license_type")
}

If I am not missing something, it should run endless and print licenseType. Instead, licenseType is printed once and then the program hangs

[sipos-david]

We are also affected by this. Using the DAO API findByIdAndUpdate function in a newSuspendedTransaction also leads to this bug.