bugGNU Screen - Bugs: bug #64190, Extremely slow startup due to fd...

 
 

bug #64190: Extremely slow startup due to fd polling?

Submitter:  None
Submitted:  Sun 14 May 2023 03:27:45 PM UTC
   
 
Category:  None Severity:  3 - Normal
Priority:  * 5 - Normal Status:  Need Investigation
Privacy:  Public Assigned to:  None
Open/Closed:  Open Release:  4.9.0
Fixed Release:  None Planned Release:  None
Work Required:  None
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Wed 09 Aug 2023 09:40:56 PM UTC, comment #1: 

Hey,
thanks for reporting, but what kind of fix are you waiting for exactly?

Does screen also slow without docker? Can you reproduce it with other container implementation like podman?

Alexander Naumov <anaumov>
Group administrator
Sun 14 May 2023 03:27:45 PM UTC, original submission:  

I use screen in a docker container on Home Assistant OS on a x86 machine.

```
# uname -a
Linux core-ssh 6.1.25 #1 SMP PREEMPT_DYNAMIC Tue Apr 25 11:50:31 UTC 2023 x86_64 Linux

# screen -v
Screen version 4.09.00 (GNU) 30-Jan-22

# cat /etc/os-release
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.17.3
PRETTY_NAME="Alpine Linux v3.17"
HOME_URL="https://alpinelinux.org/"
BUG_REPORT_URL="https://gitlab.alpinelinux.org/alpine/aports/-/issues"
```

Just running `screen -v` is very slow as well.

Very slow means tens of seconds or minutes - prior to the latest update of the docker container, this took about 1 second max.

```
strace -f -o screen.log screen -v
```

The screen.log shows many lines similar to the following:

```
22942 poll([{fd=3, events=0}, {fd=4, events=0}, {fd=5, events=0}, {fd=6, events=0}, {fd=7, events=0}, {fd=8, events=0}, {fd=9, events=0}, {fd=10, events=0}, {fd=11, events=0}, {fd=12, events=0}, {fd=13, events=0}, {fd=14, events=0}, {fd=15, events=0}, {fd=16, events=0}, {fd=17, events=0}, {fd=18, events=0}, {fd=19, events=0}, {fd=20, events=0}, {fd=21, events=0}, {fd=22, events=0}, {fd=23, events=0}, {fd=24, events=0}, {fd=25, events=0}, {fd=26, events=0}, {fd=27, events=0}, {fd=28, events=0}, {fd=29, events=0}, {fd=30, events=0}, {fd=31, events=0}, {fd=32, events=0}, {fd=33, events=0}, {fd=34, events=0}, ...], 1024, 0) = 1024 ([{fd=3, revents=POLLNVAL}, {fd=4, revents=POLLNVAL}, {fd=5, revents=POLLNVAL}, {fd=6, revents=POLLNVAL}, {fd=7, revents=POLLNVAL}, {fd=8, revents=POLLNVAL}, {fd=9, revents=POLLNVAL}, {fd=10, revents=POLLNVAL}, {fd=11, revents=POLLNVAL}, {fd=12, revents=POLLNVAL}, {fd=13, revents=POLLNVAL}, {fd=14, revents=POLLNVAL}, {fd=15, revents=POLLNVAL}, {fd=16, revents=POLLNVAL}, {fd=17, revents=POLLNVAL}, {fd=18, revents=POLLNVAL}, {fd=19, revents=POLLNVAL}, {fd=20, revents=POLLNVAL}, {fd=21, revents=POLLNVAL}, {fd=22, revents=POLLNVAL}, {fd=23, revents=POLLNVAL}, {fd=24, revents=POLLNVAL}, {fd=25, revents=POLLNVAL}, {fd=26, revents=POLLNVAL}, {fd=27, revents=POLLNVAL}, {fd=28, revents=POLLNVAL}, {fd=29, revents=POLLNVAL}, {fd=30, revents=POLLNVAL}, {fd=31, revents=POLLNVAL}, {fd=32, revents=POLLNVAL}, {fd=33, revents=POLLNVAL}, {fd=34, revents=POLLNVAL}, ...])
```


I notice that the value for 'fd' is continuously increasing.  On line 3196 of the log I get:

```
22942 poll([{fd=3215363, events=0}, {fd=3215364, events=0}, {fd=3215365, events=0}, {fd=3215366, events=0}, {fd=3215367, events=0}, {fd=3215368, events=0}, {fd=3215369, events=0}, {fd=3215370, events=0}, {fd=3215371, events=0}, {fd=3215372, events=0}, {fd=3215373, events=0}, {fd=3215374, events=0}, {fd=3215375, events=0}, {fd=3215376, events=0}, {fd=3215377, events=0}, {fd=3215378, events=0}, {fd=3215379, events=0}, {fd=3215380, events=0}, {fd=3215381, events=0}, {fd=3215382, events=0}, {fd=3215383, events=0}, {fd=3215384, events=0}, {fd=3215385, events=0}, {fd=3215386, events=0}, {fd=3215387, events=0}, {fd=3215388, events=0}, {fd=3215389, events=0}, {fd=3215390, events=0}, {fd=3215391, events=0}, {fd=3215392, events=0}, {fd=3215393, events=0}, {fd=3215394, events=0}, ...], 1024, 0) = 1024 ([{fd=3215363, revents=POLLNVAL}, {fd=3215364, revents=POLLNVAL}, {fd=3215365, revents=POLLNVAL}, {fd=3215366, revents=POLLNVAL}, {fd=3215367, revents=POLLNVAL}, {fd=3215368, revents=POLLNVAL}, {fd=3215369, revents=POLLNVAL}, {fd=3215370, revents=POLLNVAL}, {fd=3215371, revents=POLLNVAL}, {fd=3215372, revents=POLLNVAL}, {fd=3215373, revents=POLLNVAL}, {fd=3215374, revents=POLLNVAL}, {fd=3215375, revents=POLLNVAL}, {fd=3215376, revents=POLLNVAL}, {fd=3215377, revents=POLLNVAL}, {fd=3215378, revents=POLLNVAL}, {fd=3215379, revents=POLLNVAL}, {fd=3215380, revents=POLLNVAL}, {fd=3215381, revents=POLLNVAL}, {fd=3215382, revents=POLLNVAL}, {fd=3215383, revents=POLLNVAL}, {fd=3215384, revents=POLLNVAL}, {fd=3215385, revents=POLLNVAL}, {fd=3215386, revents=POLLNVAL}, {fd=3215387, revents=POLLNVAL}, {fd=3215388, revents=POLLNVAL}, {fd=3215389, revents=POLLNVAL}, {fd=3215390, revents=POLLNVAL}, {fd=3215391, revents=POLLNVAL}, {fd=3215392, revents=POLLNVAL}, {fd=3215393, revents=POLLNVAL}, ...])
```

Anonymous

 

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    Date Changed by Updated Field Previous Value => Replaced by
    2023-08-09 anaumov StatusNone Need Investigation

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