I've just made the switch from Ubuntu to Fedora 33 for my main desktop
system. Of the few teething problems I am going through, the initial
8192 limit for fs.inotify.max_user_watches was probably causing the most
side effects. As a developer, I pretty much have netbeans open all day
and am forever tailing log files, so I hit this problem pretty much
straight away.

After some digging around I found a script to list the current count of
watchers per process. The half-dozen worst offenders were:-

    INOTIFY
    WATCHER
     COUNT     PID     CMD
----------------------------------------
    4903     4620  /data/Applications/java/jdk-15/bin/java
-Djdk.home=/data/Applications/java/jdk-15 -classpath
/data/Applications/netbeans
     3573     3032  /usr/libexec/tracker-miner-fs-3
       64     2022  /usr/lib/systemd/systemd --user
       47     2663  /usr/libexec/gsd-xsettings
       27    34846  /usr/share/atom/atom --type=renderer
--enable-experimental-web-platform-features
--field-trial-handle=123480363484759119
       18     2812  /usr/bin/gnome-software --gapplication-service

So netbeans + tracker-miner had pretty much consumed the entire pool
within an hour of starting the system.

I've bumped the figure up to 65K by adding an entry to /etc/sysctl.conf
and asked on #fedora if anyone knew of the side effects of having a high
number - the only answers found were that approx 1K of unswapable kernel
memory is used per watcher. So this increase only puts an additional
57MB of such memory usage onto my system.

Are there any other side effects of this to worry about?

If not, then perhaps the default should be significantly increased with
the aim of removing the problem for new users with modern desktop/laptop
machines which probably have 4GB+ RAM. I've not rebooted my machine
overnight and netbeans is now up to 13,000 watches and tracker-miner
upto 4,500. So in less than 24 hours I have exceeded 16K watches.

Perhaps an new default value in the region of 32K - 64K would be more
appropriate?


-- Gargoyle
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