# Julia is busy on one thread all the time

**URL:** <https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428>\
**Category:** General Usage\
**Created:** [January 16, 2021, 9:28am UTC](https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428 "2021-01-16T09:28:53Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Xijiang\_Yu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xijiang_yu/32/14439_2.png) [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)\
**Post date:** [January 16, 2021, 9:28am UTC](https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428/1 "2021-01-16T09:28:54Z")

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Julia 1.7.0-DEV.320

 ![Screenshot from 2021-01-16 10-26-18](https://global.discourse-cdn.com/julialang/original/3X/2/2/2244c41bbb991b5cccd7c1407447aad90db63384.png)

There is always one thread almost always 100% occupied on my machine. I have only a REPL running, and I called no function.

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**Author:** ![Skoffer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/skoffer/32/378_2.png) [@Skoffer](https://discourse.julialang.org/u/Skoffer)\
**Post date:** [January 16, 2021, 10:39am UTC](https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428/2 "2021-01-16T10:39:20Z")

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Maybe you have something in your startup.jl?

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**Author:** ![Xijiang\_Yu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xijiang_yu/32/14439_2.png) [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)\
**Post date:** [January 16, 2021, 12:04pm UTC](https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428/3 "2021-01-16T12:04:55Z")

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Found only one `startup.jl`, which is in my Julia pulled repo, which is also empty.

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**Author:** ![Xijiang\_Yu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xijiang_yu/32/14439_2.png) [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)\
**Post date:** [January 17, 2021, 1:46pm UTC](https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428/4 "2021-01-17T13:46:53Z")

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It turned out to be my `jupyter-lab`. Though there are only some markdown lines for one notebook only. Have to kill `jupyter-lab` when I am not using it.

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**Author:** ![Xijiang\_Yu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xijiang_yu/32/14439_2.png) [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)\
**Post date:** [February 1, 2021, 11:12am UTC](https://discourse.julialang.org/t/julia-is-busy-on-one-thread-all-the-time/53428/5 "2021-02-01T11:12:25Z")

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`jupyter-lab` says that `IJulia` kernel for julia-1.7 is “untrusted”. Mine is totally not usable.

Downgrading to julia1.5.3 did the job. The CPU is not that busy any more.

Perhaps it is the problem from the combination of julia-1.7 and its IJulia.