Memory Leak proftpd-basic Version 1.3.5e-1build1

[Colin Watson]

On Sun, Dec 08, 2019 at 05:39:53PM +0000, Niklas Brückelmayer wrote:
> I want to report a bug in proftpd-basic.

Bug reports go in Launchpad, not here.  However ...

> I installed this software thru "apt install proftpd-basic" and got
> verion 1.3.5e-1build1
> 
> In this version there is a memory leak because when I transfer huge
> amounts of data (in my example approx. 500GB) all available RAM got
> "cached" and Linux starts to use swap!

Cached data in RAM is good (it means your system is keeping things in
RAM when it might possibly save it from rereading them more slowly from
disk), and using swap isn't necessarily bad.  If your system can make
better use of the available RAM than by using it to keep bits of running
but rarely-used processes in memory, then it may decide to swap out
parts of those processes, and this is fine.

Swap *thrashing* (being so RAM-constrained that your system ends up
spending too long swapping pages of memory back and forward between RAM
and disk, at the cost of getting anything useful done) is bad.  Merely
using swap at all is not bad: it just indicates that your system is
taking advantage of having a couple of different tiers of virtual memory
with different performance characteristics, and is moving rarely-used
things to the slower tier.

In order to show evidence of a memory leak in proftpd, you would need to
show that the proftpd process itself is growing.  But that's not what
memory that you see as "buff/cache" in top(1) or free(1) output is, and
what you've described so far sounds like normal behaviour to me.

-- 
Colin Watson                                       [cjwatson at ubuntu.com]