ClockDrift Warning


I am getting warning for clock drift in my logger.
I went through couple of forum answers but didn’t really understood the cause of this warning.

PS: I have SQL Tags updating every 1 second/5 Seconds, do it really have to do with this warnings?

Regards,
Richita Pandey.

That’s likely a garbage collection “pause-the-world”. When happening so fast, that suggests you haven’t given your gateway enough memory to work with (set in ignition.conf and restart). Show your gateway’s Performance Status page.

1 Like

Seems like plenty of memory…

Is this 7.9 or 8.x? Might be worth making sure G1GC is being used if it’s 7.9.

What’s the hardware here? Sustained CPU usage seems maybe a little high without justification.

(Tagged 7.9) Also ensure G1GC has a maximum pause milliseconds target. I recommend 100ms, as the default is 1 second. That doesn’t play well with the 1 second clock drift detector.

Pretty sure the default has always been 200ms, not 1s.

@Richita_Pandey if you can upload your ignition.conf file that would help.

I don’t have the access to that ingition.conf file.
If you can guide me to check few config setting, I can check with team to get that details.

Interested in the contents of the section that looks something like this:

# Java Additional Parameters
wrapper.java.additional.1=-XX:+UseConcMarkSweepGC
wrapper.java.additional.2=-XX:+CMSClassUnloadingEnabled
wrapper.java.additional.3=-Ddata.dir=data
wrapper.java.additional.4=-Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false
#wrapper.java.additional.5=-Xdebug
#wrapper.java.additional.6=-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000
1 Like

I stand corrected. Now I’m going to wonder how I mislearned that. /:

# Java Additional Parameters
wrapper.java.additional.1=-XX:+UseG1GC
wrapper.java.additional.2=-XX:MaxGCPauseMillis=100
wrapper.java.additional.3=-XX:+CMSClassUnloadingEnabled
wrapper.java.additional.4=-Ddata.dir=data
wrapper.java.additional.5=-Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false
#wrapper.java.additional.6=-Xdebug
#wrapper.java.additional.7=-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000

# Initial Java Heap Size (in MB)
wrapper.java.initmemory=1024

# Maximum Java Heap Size (in MB)
wrapper.java.maxmemory=16384

Are you running Ignition on a VM perhaps?

No, its running on windows server OS

I believe this is what you are looking for. @Kevin.Herron

# Java Additional Parameters
wrapper.java.additional.1=-XX:+UseG1GC
wrapper.java.additional.2=-XX:MaxGCPauseMillis=100
wrapper.java.additional.3=-XX:+CMSClassUnloadingEnabled
wrapper.java.additional.4=-Ddata.dir=data
wrapper.java.additional.5=-Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false
#wrapper.java.additional.6=-Xdebug
#wrapper.java.additional.7=-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000

# Initial Java Heap Size (in MB)
wrapper.java.initmemory=1024

# Maximum Java Heap Size (in MB)
wrapper.java.maxmemory=16384

Yep, that looks fine. Not sure what else you can do. Call support and have them help you figure out why the CPU usage is constantly >30% maybe? That may very well be fine, but it’s worth looking at to be sure.

Thank you @Kevin.Herron .
Just curious to know if this issue can arise if we have network issue for some time?

That shouldn’t matter, and your CPU usage and memory pattern seem very consistent.

1 Like

Aside from the longer pauses your system looks fine. Longer pauses like that are usually only seen on crappy hardware or when running in a virtual machine.

2 Likes

How much RAM does the server have? Is Ignition the only software running on this machine (e.g. database, designer, client, etc…)

1 Like

This may or may not be relevant, I recently discovered that vulnerability scanning can spike CPU usage dramatically and cause clock drifts. In my case it was a daily Nessus scan, adding a 2nd CPU resolved it for me.