[Bug 1764311] [NEW] KIO sftp high CPU usage after being left idle (endless loop?)

[Macros (Roger Rösch)]

Public bug reported:

Dolphin was left open overnight being connected via sftp://***@host:port/folder/path.
(Two targets, one continuously reachable under host:port, one went offline during the night)
Returning to the PC I found 4 sftp.so processes consuming 50% of a CPU core each.
They continued to do so after the folders in Dolphin were closed, and even after Dolphin itself was closed.
They responded to SIGTERM.

This is strace output from 1 of the processes, the same which apport was
used on:

ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
(continues to repeat, seems like its stuck in a loop)

Kubuntu 18.04 Beta 2, kde-runtime (4:17.08.3-0ubuntu1)

What I expected to happen:
No high CPU usage, maybe no sftp.so process at all as the conenction was idle.

What happened instead:
4 sftp.so processes using 200% CPU of my quad core, consuming energy and shortening the lifespan of my system.

Feel free to contact me with questions, I can try to reproduces the problem.
Also I will leave one of the processes suspended for 1-3 days after filing this report, so I can send a SIGCONT and give further information on it if requested.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: kde-runtime 4:17.08.3-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
Date: Mon Apr 16 09:54:24 2018
ExecutablePath: /usr/bin/kdeinit5
ProcEnviron:

SourcePackage: kde-runtime
UpgradeStatus: Upgraded to bionic on 2018-04-10 (5 days ago)

** Affects: kde-runtime (Ubuntu)
Importance: Undecided
Status: New


** Tags: amd64 apport-bug bionic
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Title:
KIO sftp high CPU usage after being left idle (endless loop?)

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[Brian G.]

** Also affects: archlinux
Importance: Undecided
Status: New
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Title:
KIO sftp high CPU usage after being left idle (endless loop?)

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[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: kde-runtime (Ubuntu)
Status: New => Confirmed
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Title:
KIO sftp high CPU usage after being left idle (endless loop?)

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[Brian G.]

I'm using KDE on Arch Linux, but I'm also experiencing the exact same
situation, and have been for months. I tend to leave my systems running
24/7 and often notice one or more sftp.so processes in top taking up
significant CPU resources. I did notice the CPU usage is worse when my
Dolphin sftp sessions are unable to connect to their target host (I use
a VPN to connect to some of the hosts, which I don't leave running all
the time, while the respective Dolphin window remains open). Often CPU
usage is reduced (although still not 0) once I reactivate the VPN.
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Title:
KIO sftp high CPU usage after being left idle (endless loop?)

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[Brian G.]

I should also mention that I tend to kill the sftp.so processes with
signal 15 when they act up, and they seem to eventually respawn on their
own, but I'm not sure whether that is by system restart or something
else (I haven't tracked it in that much detail).
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Title:
KIO sftp high CPU usage after being left idle (endless loop?)

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[Juan Luis García Zapata]

Same problem: Dolphin sftp session open 12 hours (in a laptop,
suspending between worktimes). I end with several sftp.so processes with
high CPU use.

A workaround is to use fish protocol in the Dolphin tab.
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Title:
KIO sftp high CPU usage after being left idle (endless loop?)

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[Macros (Roger Rösch)]

** Description changed:

Dolphin was left open overnight being connected via sftp://***@host:port/folder/path.
(Two targets, one continuously reachable under host:port, one went offline during the night)
Returning to the PC I found 4 sftp.so processes consuming 50% of a CPU core each.
They continued to do so after the folders in Dolphin were closed, and even after Dolphin itself was closed.
They responded to SIGTERM.

This is strace output from 1 of the processes, the same which apport was
used on:

ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
ppoll([{fd=4, events=POLLIN}], 1, {tv_sec=0, tv_nsec=1000000}, NULL, 8) = 0 (Timeout)
write(3, "\1\0\0\0\0\0\0\0", 8) = 8
(continues to repeat, seems like its stuck in a loop)

Kubuntu 18.04 Beta 2, kde-runtime (4:17.08.3-0ubuntu1)

What I expected to happen:
- No high CPU usage, maybe no sftp.so process at all as the conenction was idle.
+ No high CPU usage, maybe no sftp.so process at all as the connection was idle.

What happened instead:
4 sftp.so processes using 200% CPU of my quad core, consuming energy and shortening the lifespan of my system.

- Feel free to contact me with questions, I can try to reproduces the problem.
+ Feel free to contact me with questions, I can try to reproduce the problem.
Also I will leave one of the processes suspended for 1-3 days after filing this report, so I can send a SIGCONT and give further information on it if requested.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: kde-runtime 4:17.08.3-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
Date: Mon Apr 16 09:54:24 2018
ExecutablePath: /usr/bin/kdeinit5
ProcEnviron:
-
+
SourcePackage: kde-runtime
UpgradeStatus: Upgraded to bionic on 2018-04-10 (5 days ago)
--
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Bugs, which is subscribed to kde-runtime in Ubuntu.
https://bugs.launchpad.net/bugs/1764311

Title:
KIO sftp high CPU usage after being left idle (endless loop?)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/kde-runtime/+bug/1764311/+subscriptions