How-to debug Nagvis

In this how-to, we will explain to you how to debug Nagvis performance issues

LAST TESTED ON CHECKMK 2.3.0P1

Table of Contents

Getting Started

Background information regarding this subject is available in our Official documentation

Basics

Check the OMD <SITENAME> performance graphs of the affected

Important are the following graphs
- Livestatus Connects and Requests - localhost - OMD nagnis_central performance.
- Livestatus Requests per Connection - localhost - OMD nagnis_central performance.
- Livestatus usage - localhost - OMD nagnis_central performance.
- Check_MK helper usage - localhost - OMD nagnis_central performance.
Do you see peaks in these graphs? If yes, please check the liveproxyd.log inside the site user context.
Please check the Livestatus Proxy settings.
- "Maximum concurrent Livestatus connections": inside the global and site-specific global settings.
- "Livestatus Proxy default connection parameters": inside the global and site-specific global settings.
  
  We recommend using the default levels. In some cases, it makes sense to configure higher values. Please ask the support for some guidance.
Cleanup your map:
- Do you have objects in your map that are no longer available in Checkmk?
- Do you have a map with nested maps? Please check if you have objects that are no longer available in Checkmk.
How often is your Nagvis map refreshing? You can modify this value.

If the map takes a lot of time to open, you might need to debug further. In this case, we recommend checking the Livestatus queries while reloading the map.

Network analyze

To see how long the map really needs, we recommend using the network analyzer of your internet browser: Enable Checkmk profiling#NetworkAnalyzewiththeinternetbrowser.

Debugging with Livestatus

Enable the debug log

How to collect troubleshooting data for various issue types#LivestatusProxy

Debug with the lq queries

The best way to debug with the lq queries is:

tail -f ~/var/log/liveproxyd.log >/path/to/file.txt
reload the nagvis map
analyze the file

Detect long-running lq query.

Do you see any:

bigger lq query
a log query
a periodical message

You can try to execute this query via the network and see how long it takes:

Livestatus queries#Livestatusqueriesovernetwork

One example

Infrastructure

OS: Ubuntu 20.4

Version: Checkmk 1.6.0p24

Sites: 1 Central and one Remote

The map

This is a dynamic map with my remote site as a backend. I created and accessed the map via the central site.

Screenshot showing showing the web inspector

The Debugging

This approach is only if you're running a distributed setup. So, in this case, you can run that command on the central site.

If running a single site, please increase livestatus logging (How to collect troubleshooting data for various issue types#Core) to debug and check the cmc.log.

OMD[mysite]:~$ tail -f var/log/liveproxyd.log >/tmp/lq_nagvis.txt

OMD[mysite]:~$ cat /tmp/lq_nagvis.txt |grep "GET downtimes" |more
2021-07-21 13:53:04,645 [10] [cmk.liveproxyd.(1108792).Site(cmes).Client(13)] Send request 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = random_095543
1380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,646 [10] [cmk.liveproxyd.(1108792).Site(cmes).Thread(Thread-2).Channel(7)] Send: 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = ran
dom_0955431380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,696 [10] [cmk.liveproxyd.(1108792).Site(cmes).Client(13)] Send request 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = random_095543
1380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,697 [10] [cmk.liveproxyd.(1108792).Site(cmes).Thread(Thread-2).Channel(7)] Send: 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = ran
dom_0955431380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,747 [10] [cmk.liveproxyd.(1108792).Site(cmes).Client(13)] Send request 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = random_095543
1380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,748 [10] [cmk.liveproxyd.(1108792).Site(cmes).Thread(Thread-2).Channel(7)] Send: 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = ran
dom_0955431380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,798 [10] [cmk.liveproxyd.(1108792).Site(cmes).Client(13)] Send request 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = random_095543
1380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'
2021-07-21 13:53:04,798 [10] [cmk.liveproxyd.(1108792).Site(cmes).Thread(Thread-2).Channel(7)] Send: 'GET downtimes\nColumns: author comment start_time end_time\nFilter: host_name = ran
dom_0955431380\nOutputFormat: json\nKeepAlive: on\nResponseHeader: fixed16\n\n'

The whole logfile: lq_nagvis.txt

What I noticed in the logfile

A significant amount of lq "GET downtimes" commands during the map reload

If I count the "GET downtimes" lines, there are 4836

OMD[mysite]:~$ cat /tmp/lq_nagvis.txt |grep "GET downtimes" |wc -l
4836

All the other commands look small and reasonable.

Further debugging

I noticed a lot of "GET downtimes" from the log. Whenever I reload the map, my central site sends thousands of commands via livestatus.

When I check my Checkmk site, I set several host downtimes. This could explain why my central site collects all Downtimes before nagvis shows the map.

Screenshot showing the all host page

The Workaround

Remove all downtimes. The map will open faster
Access the map directly via the remote site/local site

We fixed this behavior with Checkmk 2.0. The downtimes will not affect the reload time of the map

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