Tried the same python minimal application with pyqt5 (qt 5.9.5) - and
no, it does not happen.
So it seems to be a QT4 problem somehow in connection to the gnome-
panel, because this does not happen with the same QT4 application and
fbpanel in the same environment.
stracing the gnome-panel with this pyqt5 app, a similar output is
logged, but not as frequent as with qt4:
restart_syscall(<... resuming interrupted poll ...>) = 1
recvmsg(3, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\34\0\260\202\275\2\0\0\21\2\0\0:\201\247\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 32
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}], 3,
-1) = 1 ([{fd=3, revents=POLLIN}])
recvmsg(3, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\34\0\260\202\275\2\0\0\21\2\0\0R\324\247\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0",
iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 32
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}], 3,
-1
I attached the pyqt5 tray app if somebody wants to take a look at that.
But the CPU load disappears with QT5.
** Attachment added: "python-tray-qt5.tar.gz"
https://bugs.launchpad.net/ubuntu/+source/gnome-panel/+bug/1779663/+attachment/5159066/+files/python-tray-qt5.tar.gz
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https://bugs.launchpad.net/bugs/1779663
Title:
QT4 Tray application and CPU load in 18.04
Status in gnome-panel package in Ubuntu:
Incomplete
Bug description:
Ubuntu 18.04 LTS
Session: gnome-flashback
Tested with: gnome-panel: 3.26.0-1ubuntu5 / 3.28.0-1ubuntu1 (cosmic)
We recognized a steady CPU load of about 2% when starting our QT4 tray
application. To eliminate any issues in our application, we created a
minimal python qt4 tray app (attached).
As soon as this app is started, the gnome-panel process gets a CPU load of
about 2%.
When stracing the gnome-panel, we recognize a repeating log pattern:
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}],
3, 0) = 0 (Timeout)
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
writev(3, [{iov_base="\212\5\4\0f\26 \0\0\0\26\0\26\0\2\0\217\3\4\0U\1 \0f\26
\0\0\0\0\0"..., iov_len=40}, {iov_base=NULL, iov_len=0}, {iov_base="",
iov_len=0}], 3) = 40
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}],
3, 13) = 0 (Timeout)
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
writev(3, [{iov_base="5 \4\0g\26 \0\3\0 \0\26\0\2\0\213\4\6\0h\26 \0g\26
\0&\0\0\0"..., iov_len=236}, {iov_base=NULL, iov_len=0}, {iov_base="",
iov_len=0}], 3) = 236
recvmsg(3, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="[\2\353kT\1
\0U\1 \0\200)y\0\0\0\26\0\26\0\2\0\n\5h\3\26\0\30\0", iov_len=4096}],
msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 32
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}],
3, 0) = 0 (Timeout)
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
writev(3, [{iov_base="\212\5\4\0i\26 \0\0\0\26\0\26\0\2\0\217\3\4\0U\1 \0i\26
\0\0\0\0\0"..., iov_len=40}, {iov_base=NULL, iov_len=0}, {iov_base="",
iov_len=0}], 3) = 40
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}],
3, 13) = 0 (Timeout)
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
writev(3, [{iov_base="5 \4\0j\26 \0\3\0 \0\26\0\2\0\213\4\6\0k\26 \0j\26
\0&\0\0\0"..., iov_len=236}, {iov_base=NULL, iov_len=0}, {iov_base="",
iov_len=0}], 3) = 236
recvmsg(3, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="[\2\371kT\1
\0U\1 \0\217)y\0\0\0\26\0\26\0\2\0\n\5h\3\26\0\30\0", iov_len=4096}],
msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 32
recvmsg(3, {msg_namelen=0}, 0) = -1 EAGAIN (Resource temporarily
unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=6, events=POLLIN}],
3, 0) = 0 (Timeout)
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
The trayapp is doing nothing. Can anybody explain how to stop this behaviour
in gnome-panel? Thanks!
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