Bug#870302: pavucontrol: High CPU usage

[Nelson A. de Oliveira]

Package: pavucontrol
Version: 3.0-3.1
Severity: normal

Hi!

I saw that pavucontrol uses about 2.4% ~  3.3% of CPU without doing
anything (when nothing is playing a sound in the computer).

Trying to see what is happening with strace there is a lot (really a
lot) of polling:

=====
read(12, "\1\0\0\0\0\0\0\0", 8)         = 8
getpid()                                = 23673
getpid()                                = 23673
getpid()                                = 23673
getpid()                                = 23673
write(10, "\1\0\0\0\0\0\0\0", 8)        = 8
recvmsg(3, {msg_namelen=0}, 0)          = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}], 5, 0) = 0 (Timeout)
recvmsg(3, {msg_namelen=0}, 0)          = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}], 5, 19980) = 1 ([{fd=12, revents=POLLIN}])
read(12, "\1\0\0\0\0\0\0\0", 8)         = 8
getpid()                                = 23673
getpid()                                = 23673
getpid()                                = 23673
getpid()                                = 23673
write(10, "\1\0\0\0\0\0\0\0", 8)        = 8
recvmsg(3, {msg_namelen=0}, 0)          = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}], 5, 0) = 0 (Timeout)
recvmsg(3, {msg_namelen=0}, 0)          = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}], 5, 0) = 0 (Timeout)
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
writev(3, [{iov_base="5\30\4\0sE\300\1\3\0\300\1\223\3\n\0\213\4\6\0tE\300\1sE\300\1*\0\0\0"..., iov_len=1608}, {iov_base=NULL, iov_len=0}, {iov_base="", iov_len=0}], 3) = 1608
recvmsg(3, {msg_namelen=0}, 0)          = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}], 5, 20000) = 1 ([{fd=12, revents=POLLIN}])
(...)
=====

Maybe this could somehow be improved?
Wasting CPU for polling like this doesn't seem so right.

Thank you!

Best regards,
Nelson

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable-debug'), (200, 'unstable'), (100, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=pt_BR.UTF-8, LC_CTYPE=pt_BR.UTF-8 (charmap=UTF-8), LANGUAGE=pt_BR:pt:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages pavucontrol depends on:
ii  libatk1.0-0              2.24.0-1
ii  libatkmm-1.6-1v5         2.24.2-2
ii  libc6                    2.24-12
ii  libcairo-gobject2        1.14.10-1
ii  libcairo2                1.14.10-1
ii  libcairomm-1.0-1v5       1.12.2-1
ii  libcanberra-gtk3-0       0.30-3
ii  libcanberra0             0.30-3
ii  libgcc1                  1:7.1.0-10
ii  libgdk-pixbuf2.0-0       2.36.5-2
ii  libglib2.0-0             2.52.3-1
ii  libglibmm-2.4-1v5        2.50.1-1
ii  libgtk-3-0               3.22.16-1
ii  libgtkmm-3.0-1v5         3.22.1-1
ii  libpango-1.0-0           1.40.6-1
ii  libpangocairo-1.0-0      1.40.6-1
ii  libpangomm-1.4-1v5       2.40.1-3
ii  libpulse-mainloop-glib0  10.0-2
ii  libpulse0                10.0-2
ii  libsigc++-2.0-0v5        2.10.0-1
ii  libstdc++6               7.1.0-10
ii  libx11-6                 2:1.6.4-3

Versions of packages pavucontrol recommends:
ii  pulseaudio  10.0-2

pavucontrol suggests no packages.

-- no debconf information