# Turing checkpointing by callbacks

**URL:** https://discourse.julialang.org/t/turing-checkpointing-by-callbacks/99293
**Category:** Probabilistic Programming
**Tags:** turing
**Created:** [May 23, 2023, 3:42pm UTC](https://discourse.julialang.org/t/turing-checkpointing-by-callbacks/99293 "2023-05-23T15:42:28Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![astro-kevin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/astro-kevin/32/43342_2.png) [@astro-kevin](https://discourse.julialang.org/u/astro-kevin)
#### Post date: [May 23, 2023, 3:42pm UTC](https://discourse.julialang.org/t/turing-checkpointing-by-callbacks/99293/1 "2023-05-23T15:42:28Z")

</div>

How does one save a chain via callbacks in Turing? Right now, I have something like:

```julia
function checkpoint(rng, model, sampler, sample, state, i; kwargs...)
    if i % 1000 == 0
        serialize("testchainfull$i", chn)
    end
end

```

with the function being called in the callbacks keyword in the sample method. This doesn’t actually seem to save anything or error out. What am I missing?