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  • Provide a minimal agent for instrumenting methods with flight recorder events
  • Piggybacks on the flight recorder capabilities to provide :
    • Provides low overhead event generation
    , cheap
    • Cheap time stamping
    • Allows subsequent enablement/disablement of generated events using normal JFR templates
    (In other words, to disable an instrumentation point, no subsequent redefinition is required.) 
  • Clear and precise syntax
    (No wildcards. Instrumentation points meant to be added with assistance from tooling, but syntax should be easy enough to be manually edited, if required.) 
  • Minimal overhead in terms of added code/generated classes
    (On parity with manually added events.) 
  • Loadable as an agent into an already running runtime
    (Can redefine classes.)
  • Controllable through a JMX MBean
    (Perhaps simply an operation taking a new probe definition.)
  • Must be extremely safe out of the box
    • No calling methods (avoiding halting problems) / unexpected exceptions (except possibly when converters enabled?)
    • No implicit type conversions (boxing of wrapper types to primitive types ok?)
    • General catch-all calls to toString(), if at all allowed, must be explicitly enabled
    • Module safe - only module redefinition is making jdk.jfr readable from instrumented modules
  • Built for production use
    • Need to have sufficient unit testing
    • Need to be tested against larger bodies of code (Oracle can help with Fusion staging and test environments etc)
    • Need to support OracleJDK 8 as well as OpenJDK 11+

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  • Should emit the minimum byte code required for emitting the event
  • Should generate the minimum amount of support classes and code required for emitting the event