Bug 1941696 - xterm shows programs' output delayed and mixed up until hitting Enter, mostly in vmware and VNC
Summary: xterm shows programs' output delayed and mixed up until hitting Enter, mostly...
Keywords:
Status: CLOSED EOL
Alias: None
Product: Fedora
Classification: Fedora
Component: xterm
Version: 35
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Tomas Korbar
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-03-22 16:03 UTC by Albert Flügel
Modified: 2022-12-13 15:20 UTC (History)
1 user (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2022-12-13 15:20:02 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)

Description Albert Flügel 2021-03-22 16:03:08 UTC
Description of problem:
After entering a command in xterm, often the output appears delayed after hitting Enter one more time or activating a different window. It happens often within VNC, very often (at least every second time i run a command) in a VMWare desktop (gnome, if that matters, but i assume, not). When the command output does not appear, when hitting keys, that do not result in scrolling, the typed characters appear and the curser moves like when typing the next command, but still the output of the previous command does not appear, finally after hitting Enter. Sometimes only the last line of command output is missing, but the next prompt is visible. Then hitting Enter the missing line appears before the prompt as if it had been there before normally. Because it is so weird and hard to believe, i made a short video, please see there:
http://getwings.eu/pub/20210322_151102.mp4
It is admittedly a bit shaky.

Version-Release number of selected component (if applicable):
xterm-366-1.fc33.x86_64

How reproducible:


Steps to Reproduce:
1. Start a desktop in a VNC server or in a virtual machine in VMware
2. Open xterm
3. Enter several (trivial, it does not matter) commands, that produce output

Actual results:
Often the expected output does not appear or only partially. After hitting Enter or activating a different window the pending output appears. Sometimes it seems, the layout of the xterm contents is mixing up lines.

Expected results:
Command output appears completely and in correct order

Additional info:
It happens since upgrading to Fedora 33. On 32 i did not have the problem. It also happens, when i start the xterm binary in xterm-351-2.fc32.x86_64.rpm from Fedora 32. So could be, the problem is not bound to xterm itself, but to VNC and VMware (?). It is NOT the shell, that is delaying the output. Aside of that this assumption would not be logical, i also strace-d the shell running in the xterm. There i can see: The missing output has been written by the shell to the pty file descriptor, but it does not appear in xterm. stracing xterm and VNC i can see, that when the missing text appears, the xterm has read from the stream to Xvnc and writes out something to it. However, i did not decode the X protocol. Using xev i could verify, that xterm received this sequence of events between the hang and immediately before showing the missing text:
FocusOut event, serial 34, synthetic NO, window 0x4000001,
    mode NotifyNormal, detail NotifyNonlinear

PropertyNotify event, serial 34, synthetic NO, window 0x4000001,
    atom 0x170 (_NET_WM_STATE), time 34429431, state PropertyNewValue

PropertyNotify event, serial 34, synthetic NO, window 0x4000001,
    atom 0x1bd (_GTK_EDGE_CONSTRAINTS), time 34429431, state PropertyNewValue

Don't know if this helps. However to me that seems to locate the problem in xterm again, not in the X-Server. Also, that it does not matter, whether i start Xorg or Xwayland (who ordered that ?) in the VMware. Could be, the issue has to do with longer processing time and delays in the chain of indirections across the several windowing systems.
In the changelog of xterm i haven't found anything pointing to such behaviour, only some crashing problem when typing combined characters. Could this be connected ? Not plausible to me.
The phenomenon does not appear in gnome-terminal. I have seen it in an older editor, too, but very very rarely and not comparably often like in xterm.

However the bahaviour is really annoying to me, especially when i'm working in the VMware instance, what i can hardly avoid.

Comment 1 Ben Cotton 2021-11-04 14:52:47 UTC
This message is a reminder that Fedora 33 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora 33 on 2021-11-30.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
Fedora 'version' of '33'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 33 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 2 Ben Cotton 2021-11-04 15:51:20 UTC
This message is a reminder that Fedora 33 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora 33 on 2021-11-30.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
Fedora 'version' of '33'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 33 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 3 Albert Flügel 2021-11-05 10:59:09 UTC
It now also happens with Xorg and is incredibly annoying, really.

Comment 4 Albert Flügel 2022-01-13 10:08:09 UTC
This seems to describe the same issue: https://bbs.archlinux.org/viewtopic.php?id=256382

Comment 5 Ben Cotton 2022-05-12 16:39:31 UTC
This message is a reminder that Fedora Linux 34 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora Linux 34 on 2022-06-07.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
'version' of '34'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, change the 'version' 
to a later Fedora Linux version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora Linux 34 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora Linux, you are encouraged to change the 'version' to a later version
prior to this bug being closed.

Comment 6 Albert Flügel 2022-05-14 09:23:05 UTC
Still the same on Fedora 35

Comment 7 Ben Cotton 2022-11-29 16:54:16 UTC
This message is a reminder that Fedora Linux 35 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora Linux 35 on 2022-12-13.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
'version' of '35'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, change the 'version' 
to a later Fedora Linux version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora Linux 35 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora Linux, you are encouraged to change the 'version' to a later version
prior to this bug being closed.

Comment 8 Ben Cotton 2022-12-13 15:20:02 UTC
Fedora Linux 35 entered end-of-life (EOL) status on 2022-12-13.

Fedora Linux 35 is no longer maintained, which means that it
will not receive any further security or bug fix updates. As a result we
are closing this bug.

If you can reproduce this bug against a currently maintained version of Fedora Linux
please feel free to reopen this bug against that version. Note that the version
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