PulseAudio Restart Bug – Solved

I enjoy my Linux computers, and one reason is the fact that many technical issues can be resolved, without having to reboot endlessly. However, in my past usage, there has been an irritating exception to this pattern. It’s common under Linux, that we can simply restart the PulseAudio Server from the command-line, using one out of several methods, and that the subject should be done with. But alas, every time I have ever restarted PulseAudio in this way, or, if the server restarted on its own, afterwards, when looking up the Plasma 5 -generated status display (which is actually referred to as “Phonon”), I’d be missing a Devices List, like so:

Screenshot_20191026_152751

This type of display can be interpreted to mean several things, such as, that the PulseAudio server did restart, but that perhaps, it simply failed to connect to the inter-process, session-unique, message-bus. Therefore, in the past, whenever I had such a display, I eventually did what I thought I had to do, which was, to log out and back in again, or, to reboot. On my system, PulseAudio is configured such, that it runs as one user-name, and not as root.

In fact, a peculiar side effect of this bug was, that the list of available output devices was still being displayed, within ‘pavucontrol‘.

But this ordeal has now become even more inconvenient than it ever was because on the computer which I name ‘Phosphene’, the need may recur more frequently, ‘just to restart the PulseAudio server’.

However, I have finally found the true cause for this malfunction, which was, that when PulseAudio is restarted from within an existing session, it simply fails to load one module, which is also the module that it needs, in order to be able to list the available devices:

 


module-device-manager

 

In fact, there exists a script in ‘/usr/bin‘, that loads a series of X11-related modules.

Therefore, after a restart of this service, I can simply give the following command now:

 


/usr/bin/start-pulseaudio-x11

 

And Eureka! I can now obtain a list of available devices, without ever having to log out and back in, or, without ever having to reboot:

Screenshot_20191026_152853

In fact, I have created a shell-script, which I can click on as user, and which carries out this task, safely.


 

I’ve also discovered that the ‘ProjectM’ music visualization application still works, and detects the beat of the playing music as before. What this means is that theoretically, after ‘ProjectM’ was installed, instead of rebooting, I could have just restarted the PulseAudio server as described here, to get that working.


 

( Edited 2019/10/29, 23h35 … )

I know that there exists an unrelated problem, that just happens to give the same appearance within ‘Phonon’, but that cannot be resolved in this way…

Continue reading PulseAudio Restart Bug – Solved

Bug: PackageKit refreshes packages list from repositories, every 5 minutes.

I have recently installed a (Linux) Debian / Stretch Operating System, on existing hardware that I had, but an O/S version that uses Plasma 5 as its desktop manager, and that is officially a “Kanotix” build. Because Linux users often like to have the same level of comfort as Windows users, and like to be able to update and/or install software using the point-and-click method, as often as possible, Kanotix has chosen to use the GUI application “Apper” to manage software updates. This application uses the background-daemon “PackageKit”, to execute what the user told it to do, using the elevated privileges with which this background daemon runs.

Screenshot_20190220_063632

But there is a known bug in this arrangement, which has just come to my attention this morning. PackageKit was polling the repositories for software updates every 5 minutes! While some people might think it’s cool, to be up-to-date about new packages, to within 5 minutes, in fact it’s not cool. And, if the repository-servers get the idea that they’re being spammed by continuous requests, they may even black-list the IP addresses that are doing so! So what can be done as a work-around, until the coders actually fix this bug?

Continue reading Bug: PackageKit refreshes packages list from repositories, every 5 minutes.

Some Bugs of my LXDE-based Computer, ‘Klexel’

I wrote only yesterday, that I had set up a computer with the Linux desktop-manager ‘LXDE’, and that I had named that computer ‘Klexel’.

Well I’m finding out that this computer has a bug. If I leave it with its screen-locker locked for some time, and then unlock with my password, the unlock dialog seems to succeed, but only reveals a black desktop, with only the mouse-pointer visible.

I suspect that I know what causes this. The computer in question has an old ‘Intel 910′ graphics chip-set, and although it may be good the the chip-set is supported, that chip-set and its drivers have quirks. I do have OpenGL 1.4, which should be high enough a version. But it may be that ‘behind the screen-locker’, by the time I’ve unlocked the machine again, the ‘Compiz Fusion’ desktop compositor has crashed.

There are certain other quirks which point to a graphics chip problem:

  • The window title-bars sometimes don’t render, until I click in the region where the title-bar should be, in which case they reappear.
  • Wobbly Windows needs to be enabled, in order for me to be able to restore the title-bars in this simple way.

I found that a practical way to deal with this not-resuming from the screen-locker, may be, by setting the key-sequence <Ctrl>+<Alt>+<Backspace> just to kill the X-server, as it would do under KDE or Plasma 5, using the following customization. I can right-click on the Keyboard Layout Tray Icon, then left-click on “Keyboard Layout Handler Settings”, and then:

screenshot-from-2018-09-02-06-21-12_c

I have set 2 ‘setxkbmap Options':

  1. The Compose Key,
  2. The X-server kill key.

Killing the X- just prompts me for a log-in again.

Note:

There is some possibility that the Compiz crash, on resuming from a plain lock-screen, may have to do with the Compiz setting, to display a Splash Image. By default, Kanotix systems come with an animated Kanotix splash-screen, that may look nice on systems with stable graphics, and for the first few times the system is explored. We can change this splash-screen to something other than the Kanotix splash-screen.

But I have noticed that, just for Compiz to start the splash-screen, causes instability with the Intel 910 chip-set, even if it does work. So what may be happening, is that on resuming from the lock-screen, Compiz may be programmed to display the splash-screen, and doing so may be what crashes my session. And so for now, I’ve also disabled this feature, and will comment later, on whether having done so has fixed the crashes.

(Update 09/05/2018, 15h30 … )

(As of 09/02/2018 : )

Continue reading Some Bugs of my LXDE-based Computer, ‘Klexel’

xscreensaver Bug With Latest Proprietary nVidia Graphics Drivers

As described in this posting, I have just applied a major software-update to the computer I name ‘Plato’, in which I replaced its open-source graphics drivers, with the proprietary nVidia drivers, suitable for its graphics card, and for its Linux-build.

That would be drivers version ‘375.82-1~deb9u1′ , from the package manager, for a ‘Debian 9.4′ system.

I have just noticed a major bug, which other people should know about, before they also decide to go with the proprietary drivers. They tend to cause some malfunction with OpenGL-based ‘xscreensaver’ screen-savers, version ‘5.36-1′ .

The bug seems to be, that if I use the graphical configuration tool to preview several screen-savers, when I switch from one screen-saver to another, the previous GL-screen-saver being previewed fails to terminate, which in turn causes the configuration window to freeze, so that the next-chosen screen-saver cannot be previewed. A small blank rectangle takes its place, in the configuration window. When this happens, I actually need to ‘kill -9′ the screen-saver-process – belonging to the screen-saver in question and not ‘/usr/bin/xscreensaver’ – the former of which is taking up 100% of 1 CPU core with nice-time, before I can continue previewing screen-savers.

The problem with this as I see it is, it could also happen after the screen-saver has locked the screen, and when I have entered my password to unlock it. The mere fact that I was always able to unlock one GL-based screen-saver in the past was good in itself, but may only have been luck! The strangeness with which my bug seems to differ from other users’ bug-reports, is that when my OpenGL-based screen-saver was rendering to the root window – i.e., to the whole screen – it did exit properly when unlocked by me.

So as it currently stands, I have set my screen-saver on the computer ‘Plato’, to just a blank screen… :-(

At the same time, OpenGL applications seem to run just fine, like this example, just tested:

screenshot_20180430_142338

However, since the description of the screen-saver packages in the package manager states “GL(Mesa)” screen-savers, it may be better just to ‘remove’ the ‘xscreensaver-gl’ and ‘xscreensaver-gl-extra’ packages.

I found out, that this bug also affects ‘rss-glx 0.9.1-6.1′ .

(Updated 04/30/2018, 19h25 … )

Continue reading xscreensaver Bug With Latest Proprietary nVidia Graphics Drivers