### Author:  [@mrange](https://discuss.kotlinlang.org/u/mrange)
#### Post date: [August 11, 2017, 1:50pm UTC](https://discuss.kotlinlang.org/t/try-finally-in-buildsequence-finally-not-called-in-some-situations/4147/1 "2017-08-11T13:50:44Z")
I have been experimenting with buildSequence and try…finally.
If I don’t iterate the full sequence it seems finally clause is not called.
Consider this
```auto
import kotlin.coroutines.experimental.buildSequence
fun test() = buildSequence {
try {
println("Yield 1")
yield(1)
println("Yield 2")
yield(2)
println("Yield 3")
yield(3)
} finally {
println("Finally")
}
}
fun main(argv: Array) {
for (v in test().take(2))
{
println("Received: $v")
}
}
```
My expectation is that this program would print:
```auto
Yield 1
Received: 1
Yield 2
Received: 2
Finally
```
But it prints:
```auto
Yield 1
Received: 1
Yield 2
Received: 2
```
If I change to `take(100)` in order to iterate the full sequence finally seems to be invoked:
```auto
Yield 1
Received: 1
Yield 2
Received: 2
Yield 3
Received: 3
Finally
```
In a more realistic scenario this could mean that my code doesn’t call a database connection when I would expect it would.
Best Regards,
orange
---
### Author:  [@jstuyts](https://discuss.kotlinlang.org/u/jstuyts)
#### Post date: [August 11, 2017, 2:14pm UTC](https://discuss.kotlinlang.org/t/try-finally-in-buildsequence-finally-not-called-in-some-situations/4147/2 "2017-08-11T14:14:21Z")
I can explain why it is not called, but I cannot offer a solution: Your sequence is frozen at `yield(2)`. Kotlin has no way of knowing it must exit at that point (i.e. you don’t (and can’t?) send a signal to the sequence telling it to terminate), and invoke the `finally` block.
---
### Author:  [@elizarov](https://discuss.kotlinlang.org/u/elizarov)
#### Post date: [August 14, 2017, 8:11am UTC](https://discuss.kotlinlang.org/t/try-finally-in-buildsequence-finally-not-called-in-some-situations/4147/3 "2017-08-14T08:11:29Z")
The `finally` is not invoked on _abandoned coroutines_ by design. More details about this particular design decision can be found in the corresponding design document: [coroutines-examples/kotlin-coroutines-informal.md at master · Kotlin/coroutines-examples · GitHub](https://github.com/Kotlin/kotlin-coroutines/blob/master/kotlin-coroutines-informal.md#resource-management-and-gc)
---
### Author:  [@mrange](https://discuss.kotlinlang.org/u/mrange)
#### Post date: [August 14, 2017, 9:14am UTC](https://discuss.kotlinlang.org/t/try-finally-in-buildsequence-finally-not-called-in-some-situations/4147/4 "2017-08-14T09:14:15Z")
I can understand abandoned coroutines should be avoided (like aborting threads) but a major feature of lazy sequences are that they can be “abandoned”.
This makes me wonder if `try..finally` should be forbidden in `buildSequence` to avoid confusion that may lead to file, mutex lock and connection leaks.
---
### Author:  [@Tim\_van\_der\_Leeuw.1](https://discuss.kotlinlang.org/u/Tim_van_der_Leeuw.1)
#### Post date: [August 14, 2017, 11:06am UTC](https://discuss.kotlinlang.org/t/try-finally-in-buildsequence-finally-not-called-in-some-situations/4147/5 "2017-08-14T11:06:54Z")
How would you forbid it?
The yield() call could happen from a closure and the code calling the closure could wrap that in a try-finally. I don’t think there’s a way to statically analyse this all at compile-time.
Is it possible to dynamically check this at runtime, in the generated byte-code?