# Epoll\_wait occupying 40% cpu

**URL:** <https://discourse.julialang.org/t/epoll-wait-occupying-40-cpu/11977>\
**Category:** General Usage\
**Created:** [June 26, 2018, 7:04pm UTC](https://discourse.julialang.org/t/epoll-wait-occupying-40-cpu/11977 "2018-06-26T19:04:08Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![tk3369](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tk3369/32/2824_2.png) [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Post date:** [June 26, 2018, 7:04pm UTC](https://discourse.julialang.org/t/epoll-wait-occupying-40-cpu/11977/1 "2018-06-26T19:04:08Z")

</div>

I used Jupyter and finished some work few days ago. I forgot to shut down the kernel but I notice something strange today. Apparently, the julia process is occupying 40% cpu even though nothing is running.

I diagnosed further with `strace` and it turns up a bunch of repeated [epoll\_wait](http://man7.org/linux/man-pages/man2/epoll_pwait.2.html) system calls. I don’t mind it goes into a loop but it shouldn’t occupy so much cpu either. Has anyone seen such problem before? This is v0.6.3.

```julia
$ strace -p 24868
strace: Process 24868 attached
epoll_wait(5, [], 1024, 52) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 52) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 52) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 60) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 61) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 62) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 62) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 0) = 0
epoll_wait(5, [], 1024, 62) = 0

```

top:

```julia
   PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 24868 tkwong 20 0 38.865g 0.028t 0.022t S 46.5 0.9 1730:59 julia
1

```