# How to release memory from jupyter notebook?
**URL:** https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886
**Category:** Jupyter-Notebook
**Created:** [March 10, 2021, 2:39pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886 "2021-03-10T14:39:14Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@bharland](https://discourse.julialang.org/u/bharland)
#### Post date: [March 10, 2021, 2:39pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/1 "2021-03-10T14:39:14Z")
Here is a minimal example that reproduces my problem on a new JupyterLab kernel:
`x = rand(2^29); varinfo()`
shows the 4.00 Gb size of ‘x’. But
`x = nothing`
does not release this memory. varinfo shows that it is indeed 0.00 Gb, but it’s showing up with top and my system monitor.
What am I missing here? Thanks!
---
### Author:  [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)
#### Post date: [March 10, 2021, 2:41pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/2 "2021-03-10T14:41:12Z")
You can manually invoke the garbage collector with GC.gc(). It should release the memory.
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### Author:  [@bharland](https://discourse.julialang.org/u/bharland)
#### Post date: [March 10, 2021, 2:42pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/3 "2021-03-10T14:42:25Z")
You’re right! Thanks so much.
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### Author:  [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [March 10, 2021, 2:46pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/4 "2021-03-10T14:46:11Z")
The Jupyter notebook interface also stores a reference to the output value of every cell, so your giant array might still be stored as `Out[n]` where `n` is the cell number in which you computed `x`.
You can do `empty!(Out)` to clear that dictionary manually (I don’t know if this is actually a recommended thing to do, but it seems to work). Or you can restart the Jupyter kernel, but I assume that’s not what you actually want.
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### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [March 10, 2021, 4:15pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/5 "2021-03-10T16:15:55Z")
Sorry just to be clear, this is only about the output of a cell? I.e. if I have
```julia
df = CSV.read(myhugefile.csv, DataFrame)
data = df[1:10, 1:5]
df = nothing
```
in a cell then there would not be a reference to the full data read in from csv?
EDIT: I should probably just check this myself but unfortunately my computer is currently unusable due to processing some large csv files in a Jupyter notebook 🙂
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### Author:  [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [March 10, 2021, 4:28pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/6 "2021-03-10T16:28:04Z")
Yeah, as far as I know that’s correct. The `Out` dictionary just holds the value of the last expression in the cell (the same way all Julia blocks implicitly return the value of their last expression).
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### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [March 10, 2021, 5:33pm UTC](https://discourse.julialang.org/t/how-to-release-memory-from-jupyter-notebook/56886/7 "2021-03-10T17:33:21Z")
> [@rdeits](#):
>
> You can do `empty!(Out)` to clear that dictionary manually (I don’t know if this is actually a recommended thing to do, but it seems to work).
Yes, it is documented: [Using IJulia · IJulia](https://julialang.github.io/IJulia.jl/dev/manual/usage/#Input-and-output-history)