# Finalizers not running
**URL:** https://discourse.julialang.org/t/finalizers-not-running/2266
**Category:** General Usage
**Created:** [February 24, 2017, 7:48am UTC](https://discourse.julialang.org/t/finalizers-not-running/2266 "2017-02-24T07:48:38Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@maleadt](https://discourse.julialang.org/u/maleadt)
#### Post date: [February 24, 2017, 7:48am UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/1 "2017-02-24T07:48:38Z")
I’m having some trouble getting finalizers to run, it seems that in some cases finalizers are only run `atexit`, and not when the object seems unreachable and I’ve called `gc()` a couple of times.
For example, the following snippet works as expected:
```julia
type Foo
field
function Foo()
obj = new(1)
finalizer(obj, finalize)
return obj
end
end
finalized = false
function finalize(obj::Foo)
global finalized
finalized = true
msg = "Finalizing...\n"
ccall(:write, Cssize_t, (Cint, Cstring, Csize_t),
1, msg, length(msg))
end
let
foo = Foo()
end
println("Forcing GC")
for i in 1:10
gc()
end
@assert finalized
```
However, if I change `Foo` _not_ to have any fields, the finalizer isn’t run before the program exits:
```julia
type Foo
function Foo()
obj = new()
finalizer(obj, finalize)
return obj
end
end
...
ERROR: LoadError: AssertionError: finalized
Finalizing...
```
Another one, again starting from the top example from this post (ie. with `field`) but this time throwing a `MethodError` refering to an instance of `foo`:
```julia
let
foo = Foo()
@test_throws MethodError sin(foo)
end
...
ERROR: LoadError: AssertionError: finalized
Finalizing...
```
Are these genuine bugs, or am I expecting something from the gc which it can’t/doesn’t guarantee?
cc @yuyichao
---
### Author:  [@jameson](https://discourse.julialang.org/u/jameson)
#### Post date: [February 24, 2017, 12:53pm UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/2 "2017-02-24T12:53:21Z")
Objects without fields (otherwise known as singletons) are never allocated, so they never need to be freed.
---
### Author:  [@maleadt](https://discourse.julialang.org/u/maleadt)
#### Post date: [February 24, 2017, 1:02pm UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/3 "2017-02-24T13:02:13Z")
I suspected it would be something like that. The second issue is the realistic one though, where GPU array finalizers aren’t run and hence memory isn’t freed.
---
### Author:  [@jameson](https://discourse.julialang.org/u/jameson)
#### Post date: [February 24, 2017, 1:12pm UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/4 "2017-02-24T13:12:17Z")
I’m guessing that `@test_throws` is creating a new function (rather than a closure) over the variable `foo` since it sees that it is as the toplevel scope. This is perhaps a lowering bug, but one that exists for compatibility with existing code.
---
### Author:  [@yuyichao](https://discourse.julialang.org/u/yuyichao)
#### Post date: [February 24, 2017, 1:43pm UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/5 "2017-02-24T13:43:02Z")
For the second case, it was kept alive in `exception_in_transit`.
---
### Author:  [@maleadt](https://discourse.julialang.org/u/maleadt)
#### Post date: [February 24, 2017, 1:51pm UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/6 "2017-02-24T13:51:12Z")
Ah, yes, I had just reduced it to `throw(foo)`… Thanks.
---
### Author:  [@jameson](https://discourse.julialang.org/u/jameson)
#### Post date: [February 24, 2017, 4:03pm UTC](https://discourse.julialang.org/t/finalizers-not-running/2266/7 "2017-02-24T16:03:16Z")
ah, ok, so it is a bug (submitted [https://github.com/JuliaLang/julia/issues/20784](https://github.com/JuliaLang/julia/issues/20784))