[konsole] [Bug 507216] New: Konsole fails if I open 300 windows with "QProcess: Cannot create pipe (Too many open files)"; please, raise RLIMIT_NOFILE

[Askar Safin]

https://bugs.kde.org/show_bug.cgi?id=507216

            Bug ID: 507216
           Summary: Konsole fails if I open 300 windows with "QProcess:
                    Cannot create pipe (Too many open files)"; please,
                    raise RLIMIT_NOFILE
    Classification: Applications
           Product: konsole
      Version First 25.04.2
       Reported In:
          Platform: Debian testing
                OS: Linux
            Status: REPORTED
          Severity: normal
          Priority: NOR
         Component: single-process
          Assignee: konsole-devel at kde.org
          Reporter: safinaskar at mail.ru
  Target Milestone: ---

SUMMARY
Konsole fails if I open 300 windows with "QProcess: Cannot create pipe (Too
many open files)"

STEPS TO REPRODUCE
Try to open 300 Konsole windows

OBSERVED RESULT
All windows close on its own

EXPECTED RESULT
Windows should not close on its own

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian Trixie 13, x86_64
uname -a: Linux comp 6.12.35+deb13-amd64 #1 SMP PREEMPT_DYNAMIC Debian
6.12.35-1 (2025-07-03) x86_64 GNU/Linux
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.13.0
Qt Version: 6.8.2
Konsole version: 25.04.2
Wayland

ADDITIONAL INFORMATION
"journalctl" shows this:

Jul 19 07:41:26 comp konsole[2187]: org.kde.konsole: foregroundProcessGroup
master_fd < 0
Jul 19 07:41:26 comp konsole[2187]: QLayout: Cannot add a null widget to
QHBoxLayout/
Jul 19 07:41:26 comp konsole[2187]: kf.pty: Can't open a pseudo teletype
Jul 19 07:41:26 comp konsole[2187]: org.kde.konsole: foregroundProcessGroup
master_fd < 0
Jul 19 07:41:26 comp konsole[2187]: QProcess: Cannot create pipe (Too many open
files)
Jul 19 07:41:26 comp konsole[2187]: QProcess: Cannot create pipe (Too many open
files)
Jul 19 07:41:26 comp konsole[2187]: QLayout: Cannot add a null widget to
QHBoxLayout/
Jul 19 07:41:27 comp konsole[2187]: kf.pty: Can't open a pseudo teletype
Jul 19 07:41:27 comp konsole[2187]: org.kde.konsole: foregroundProcessGroup
master_fd < 0
Jul 19 07:41:27 comp konsole[2187]: QProcess: Cannot create pipe (Too many open
files)
Jul 19 07:41:27 comp konsole[2187]: QProcess: Cannot create pipe (Too many open
files)
Jul 19 07:41:27 comp konsole[2187]: QLayout: Cannot add a null widget to
QHBoxLayout/
Jul 19 07:41:27 comp konsole[2187]: kf.pty: Can't open a pseudo teletype
Jul 19 07:41:27 comp konsole[2187]: org.kde.konsole: foregroundProcessGroup
master_fd < 0
Jul 19 07:41:27 comp konsole[2187]: QLayout: Cannot add a null widget to
QHBoxLayout/
Jul 19 07:41:27 comp konsole[2187]: kf.pty: Can't open a pseudo teletype
Jul 19 07:41:27 comp konsole[2187]: org.kde.konsole: foregroundProcessGroup
master_fd < 0
Jul 19 07:41:27 comp konsole[2187]: The Wayland connection experienced a fatal
error: Too many open files
Jul 19 07:41:27 comp konsole[4941]: QLayout: Cannot add a null widget to
QHBoxLayout/
Jul 19 07:41:27 comp systemd[1371]:
app-org.kde.konsole at 282b2f16ea744533bf654a1f827f5aad.service: Main process
exited, code=exited, status=255/EXCEPTION
Jul 19 07:41:27 comp systemd[1371]:
app-org.kde.konsole at 282b2f16ea744533bf654a1f827f5aad.service: Failed with
result 'exit-code'.
Jul 19 07:41:27 comp systemd[1371]:
app-org.kde.konsole at 282b2f16ea744533bf654a1f827f5aad.service: Consumed 314ms
CPU time, 130.2M memory peak.
Jul 19 07:41:27 comp systemd[1371]: app-org.kde.konsole-2187.scope: Consumed
42.811s CPU time, 11.8G memory peak.

So, it seems Konsole opens too many files.

I added DefaultLimitNOFILE=524288:524288 to /etc/systemd/user.conf and
/etc/systemd/system.conf .
And the bug disappeared.
So I suggest to follow advice in this Poettering blog
https://0pointer.net/blog/file-descriptor-limits.html and to raise
RLIMIT_NOFILE at startup.
Possibly this change should be propagated to all KDE apps or even to all Qt
apps

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