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Running profiler on k8s

Moderators: Vladimir Kondratyev, Anton Katilin

Running profiler on k8s

Postby oali » Thu Feb 18, 2021 4:08 pm

So I'm having issues running the profiler on k8s. I was able to setup the profiler locally in a docker container and it works but I wanted to run it in the k8s cluster. I start the agent with my jar by using
Code: Select all
-agentpath:/usr/local/YourKit-JavaProfiler-2020.9/bin/linux-x86-64/libyjpagent.so=port=10002,listen=all -jar ...

I have a service that exposed the port 10002. The port of the service that is externally facing is different because k8s creates a random port. When I try and access the endpoint of the node the app is running on using the port that k8s creates I am able to see the summary page.
When I try and connect from the GUI I provide the node name in the k8s cluster where the app is running as the hostname and the profiler agent port is the port that is provided by my service. I see that the connection is green so when I click on it I see it says remote application is being profiled. After a couple of seconds it terminates and says the application was terminated or connection is lost. My app hasn't restarted at all so I don't know why the connection terminated. In the logs in k8s for the Yourkit I see the following:
Code: Select all
 error: Exception in dispatchRequest(): java.io.EOFException
        at java.base/java.io.DataInputStream.readFully(DataInputStream.java:202)
        at java.base/java.io.DataInputStream.readLong(DataInputStream.java:421)
        at com.yourkit.f.au.a(a:50)
        at com.yourkit.runtime.RequestProcessing.dispatchRequest(a:30)
        at com.yourkit.runtime.Core$5.run(a:646)
        at java.base/java.lang.Thread.run(Unknown Source)

Any idea? The connection does work but it doesn't stay connected for more than a few seconds. Am I supposed to add liveness probes to keep it connected?
Posts: 2
Joined: Thu Feb 18, 2021 3:47 pm

Re: Running profiler on k8s

Postby oali » Thu Feb 18, 2021 5:11 pm

If someone else runs into this issue I found the solution which was silly. I was running 2 replicas of the app in k8s and didn't think it was a big deal. I decided to take one of the replicas down thinking that even though I was connecting to one node and the other replica was on a different node that it wouldn't cause an issue. Guess I was wrong and it seems running the app with two or more replicas would confuse the profiler and cause it to terminate the connection.
Posts: 2
Joined: Thu Feb 18, 2021 3:47 pm

Re: Running profiler on k8s

Postby Anton Katilin » Thu Feb 18, 2021 7:25 pm

Perhaps it was a problem with a fixed port you specified for the agent with the option "port=10002". When you use this option please be sure that the port is not opened by another process. The option allows to specify a port range instead to choose a free port from, e.g. "port=10001-10010", see https://www.yourkit.com/docs/java/help/ ... s.jsp#port
Anton Katilin
Posts: 6016
Joined: Wed Aug 11, 2004 8:37 am

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