Summary

• Turn off the collection of PerfData events using an always-on periodic task
• Deprecate and obsolete PerfDataSamplingInterval
• Deprecate the jstat -t flag

Problem

• A small periodic task, StatsSampler, is running every 50ms. This causes some nominal overhead, and is unused by the vast majority of users
• On most JVMs, like G1 and ZGC, the only effect of the periodic task is to store the current time in shared perfdata file
• On SerialGC and ParallelGC it also updates the shared perfdata file with the value of the used heap counter (only copying of the value from the internal storage to the shared file; JMX users should see value updates)

Solution

• Deprecate and obsolete the PerfDataSamplingInterval
• Remove the StatsSampler and related sampling functionality
• Remove or initialize the sun.os.hrt.ticks to the value of os::elapsed_counter on startup
• Deprecate the jstat -t option

Specification

• Periodic task removed
• PerfDataSamplingInterval is marked for deprecation and obsoletion in JDK 15. Marked for removal in JDK 16.
• jstat man pages updated to reflect that the -t flags has been deprecated