Why does system flush cache every 5 minutes?

[MGanon]

Why does system flush cache every 5 minutes? Performance is bad as a result. How do I prevent cache.flush from running every 5 minutes?

[Maik Skoddow · Accepted solution]

Hi @MGanon 

in most cases, the root cause is setting a system property by any code.

Maybe there is a scheduled job which runs every 5 minutes.

But at the end I don't know any approach to find out which piece of code is doing that. I just can tell you that code owned by ServiceNow will not do that.

Kind regards
Maik

[MGanon]

I reviewed the active scheduled jobs running ever 5 minutes and reset some so they don't run as frequently. I'm not sure it that was the resolution or coincidence.

[Hitoshi Ozawa]

Refer to the following Now Support page on finding the cause of cache flush.

Cause

Below are a few causes that will lead to the cache to be rebuilt:

1) Adding or updating system properties

2) Adding or updating dictionary entries

3) Committing update sets

4) Adding or updating translations

5) Activating a plugin

6) User triggered cache flush by accessing /cache.do

Resolution

Below are the different ways to determine if a cache flush was triggered that lead to poor performance of the instance.

1) ServiceNow Performance Dashboard:

The ServiceNow Performance graphs will provide data upto 30 days and you have an option to view if any event was triggered within that time frame based on each of the nodes available.

There is an option to toggle the Diagnostic Events to on and off. Enabling this will provide you all the events that were triggered as follows. In the below picture, there was a plugin that was activated that lead to the cache flush and you can see the spikes in response time once the cache was flushed.

https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0755182

[MGanon]

The performance dashboard is how I identified that cache was getting flushed every 5 minutes.