How do I find out what inotify watches have been registered?

Question

I have my inotify watch limit set to 1024 (I think the default is 128?). Despite that, yeoman, Guard and Dropbox constantly fail, and tell me to up my inotify limit. Before doing so, I'd like to know what's consuming all my watches (I have very few files in my Dropbox).

Is there some area of /proc or /sys, or some tool I can run, to find out what watches are currently registered?

Answer 1

inotify filesystem options

sysctl fs.inotify

opened files

lsof | grep inotify | wc -l

Increase the values like this

• sysctl -n -w fs.inotify.max_user_watches=16384
• sysctl -n -w fs.inotify.max_user_instances=512

Answer 2

1. The default maximum number of inotify watches is 8192; it can be increased by writing to /proc/sys/fs/inotify/max_user_watches.
   You can use sysctl fs.inotify.max_user_watches to check current value.

2. Use tail -f to verify if your OS does exceed the inotify maximum watch limit.
   The internal implementation of tail -f command uses the inotify mechanism to monitor file changes.
   If you've run out of your inotify watches, you'll most likely to get this error:

   tail: inotify cannot be used, reverting to polling: Too many open files

3. To find out what inotify watches have been registered, you may refer to this, and this. I tried, but didn't get the ideal result. :-(

Reference:
https://askubuntu.com/questions/154255/how-can-i-tell-if-i-am-out-of-inotify-watches
https://unix.stackexchange.com/questions/15509/whos-consuming-my-inotify-resources
https://bbs.archlinux.org/viewtopic.php?pid=1340049

Answer 3

I think

sudo ls -l /proc/*/fd/* | grep notify

might be of use. You'll get a list of the pids that have a inotify fd registered.

I don't know how to get more info than this! HTH

Answer 4

Since this is high in Google results, I'm copy-pasting part of my answer from a similar question over on the Unix/Linux StackExchange:

I ran into this problem, and none of these answers give you the answer of "how many watches is each process currently using?" The one-liners all give you how many instances are open, which is only part of the story, and the trace stuff is only useful to see new watches being opened.

This will get you a file with a list of open inotify instances and the number of watches they have, along with the pids and binaries that spawned them, sorted in descending order by watch count:

sudo lsof | awk '/anon_inode/ { gsub(/[urw]$/,"",$4); print "/proc/"$2"/fdinfo/"$4; }' | while read fdi; do count=$(sudo grep -c inotify $fdi); exe=$(sudo readlink $(dirname $(dirname $fdi))/exe); echo -e $count"\t"$fdi"\t"$exe; done | sort -nr > watches

If you're interested in what that big ball of mess does and why, I explained in depth over on the original answer.

Answer 5

The following terminal command worked perfectly for me on my Ubuntu 16.04 Machine:

for foo in /proc/\*/fd/*; do readlink -f $foo; done |grep inotify |cut -d/ -f3 |xargs -I '{}' -- ps --no-headers -o '%p %U %a' -p '{}' |uniq -c |sort -n

My problem was that I had a good majority of my HDD loaded as a folder in Sublime Text. Between /opt/sublime_text/plugin_host 8992 and /opt/sublime_text/sublime_text, Sublime had 18 instances of inotify while the rest of my programs were all between 1-3.

Since I was doing Ionic Mobile App development I reduced the number of instances by 5 by adding the large Node.js folder "node_modules" to the ignore list in the Sublime settings.

"folder_exclude_patterns": [".svn", ".git", ".hg", "CVS", "node_modules"]

Source: https://github.com/SublimeTextIssues/Core/issues/1195