Understanding ReadyNow Orchestrator Generations

Configuring Generations

ReadyNow Orchestrator allows you to set different minimum size and recording durations for different generations of your profiles. Often you want to promote the first generation of your profile as quickly as possible so new JVMs are not starting with nothing, but you want your second generation to record for a longer time before promotion, so it is more complete.

You can use configuration settings for both ReadyNow Orchestrator itself and the JVM clients to change this behavior if the default values don’t deliver the desired result.

Basic Profile Recording with Default Generations

In its most basic form, you let the defaults do all the work. By default, ReadyNow Orchestrator nominates profile logs after three full generations and doesn’t place a limit on log size. Suppose you want to record a new profile while deploying code to a fleet running in production. Run with the following options:

 
java -XX:OptHubHost={host:port} \
    -XX:+EnableRNO \
    -XX:ProfileName=opthub://MyApp-v3 \
    -jar myapp.jar

In this case, all JVMs nominate their logs based on the defaults (2 minutes for the first generation, 15 minutes for the second, 30 minutes for the third, 60 minutes for the fourth) and keep recording until the JVM shuts down. For best results, do a test run in a canary instance for at least two minutes and if possible a full ten minutes. This creates generation 1 of your profile. Then restart your fleet as normal. As JVMs start up, they receive a profile from ReadyNow Orchestrator and check the generation number. If that number is less than the server-side default maximum of 3, the JVM writes out the next generation of the profile. Once there is a valid generation 3 of the profile on ReadyNow Orchestrator, none of the JVMs write any more output.

You can overrule the server-side defaults, by providing extra options, for example:

 
java -XX:OptHubHost={host:port} \
    -XX:+EnableRNO \
    -XX:ProfileName=opthub://MyApp-v3 \
    -XX:ProfileLogOutNominationMinSizePerGeneration=0:1000000\,1:10000000\,2:25000000\,3:50000000 \
    -XX:ProfileLogOutNominationMinTimeSec=0:PT2M\,1:PT15M\,2:PT30M\,3:PT60M \
    -jar myapp.jar

Capping Profile Log Recording and Maximum Generations

We can make our example above more complex:

Start your JVM with the following parameters:

 
java -XX:OptHubHost={host:port} \
    -XX:+EnableRNO \
    -XX:ProfileName=opthub://MyApp-v3 \
    -XX:ProfileLogTimeLimitSeconds=600 \
    -XX:ProfileLogOutMaxNominatedGenerationCount=2 \
    -jar myapp.jar

Priority of Generation Settings

Please take the default values into account when you define your own generation settings as these can be overruled by other default settings. Let’s look at an example:

When you want to overrule the default settings, make sure to specify all appropriate options.