[screen-devel] [bug #64190] Extremely slow startup due to fd polling?

[anonyme]

URL:
  <https://savannah.gnu.org/bugs/?64190>

                 Summary: Extremely slow startup due to fd polling?
                   Group: GNU Screen
               Submitter: None
               Submitted: dim. 14 mai 2023 15:27:45
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
                 Release: 4.9.0
         Discussion Lock: Any
           Fixed Release: None
         Planned Release: None
           Work Required: None


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Follow-up Comments:


-------------------------------------------------------
Date: dim. 14 mai 2023 15:27:45      By: Anonymous
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}, ...])
```








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