[Qgis-user] QGIS memory management in LXCs vs VMs

[David Swanlund]

Hey there,

This is admittedly a bit niche, but I thought I'd give it a shot. We're
using QGIS inside Linux Containers (LXCs) to process aerial imagery, but
are running up against what seem to be memory management problems. When we
load in imagery from the filesystem and begin panning around the map,
memory/swap consumption of course increases. However, when the system
begins to run out of memory/swap, we see different behaviour in LXCs vs
VMs. In the VM, QGIS seems to intelligently manage what data it has cached
and continues to function as it hovers near memory limits, allowing us to
keep panning and loading in new imagery. However, inside of LXCs QGIS will
keep filling memory and never clearing anything until the system fully
locks up and we have to kill QGIS or reboot the container. My initial
suspicion is that it's assuming it has full system memory rather than the
limited memory that is defined by cgroups, though this is a bit of a shot
in the dark.

We've tested and observed this behaviour in containers running both Ubuntu
20.04 with QGIS 3.16 as well as Ubuntu 22.10 with QGIS 3.28. Meanwhile, we
have a Ubuntu 20.04/QGIS 3.16 VM that seems far more stable.

Any help (or even just a pointer as to where to look next) would be greatly
appreciated!

Best,
David
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