When most of us want to make sure that our laptops are stable, and have saved their user-data, and have a fresh slate of available memory again, we just perform a reboot. However, on a tower computer which is also acting as a Web-server, this may not be such a viable option, because a true reboot would also cause said Web-server to go offline briefly. But as an alternative, we can log out the current user without shutting down the system, and then log back in again. On most Linux systems that have real desktop managers, this also restarts the X-server, and frees some additional graphics memory.
I just performed such a User-Session Restart, on the computer I name ‘Phoenix’. When I do this, it actually empties out the large amount of data which my system has swapped out. What tends to happen on this machine, which only possesses 4GB of RAM, is that its heavy KDE Desktop Manager has resource leaks, which continuously cause memory to be allocated but not used. The unused memory gets paged to the swap partition. But because it is also a 64-bit machine, there is no real risk that the system would run out of 64-bit virtual addresses, corresponding to this leaked resource. Only, the used portion of the swap partition becomes embarrassingly large. A log-out followed by a log-in, forces the desktop environment to save all its data, and in so doing, also forces all the data which has been swapped out, to be swapped back in, simultaneously.
I believe that this is reason, why actual restarts on this one machine are really so slow. It takes several minutes just for the wallpaper to disappear, and then the mouse-cursor, and then for an actual X-server-restart to take place.
At the same time, this exercise has confirmed what I already thought, which was that a ‘gstreamer’ update weeks ago, did not affect my Pulse Audio sound server adversely. I still have sound.
Also, in the province of Quebec, Daylight Savings Time started several weeks ago, and whenever this happens, my Desktop Notification Icon, ‘korgac’, starts to fire off user-notifications for scheduled events at an illogical time but persistently, around 23h00 or so, until 24h00. The only way to stop that in the short term, is actually to disable these alarms, until the desktop is given a new session. Then, as experience on my laptop ‘Klystron’ already confirmed, korgac can be re-enabled, and those illogical, wrongly-scheduled alarms stop happening.
Finally, when and if there finally is another power failure, the risk of data-loss becomes lower.
None of this should have affected system services, nor the Web-server, and therefore not my site either.
Dirk