Bug ID: JDK-8230938 Deprecate MonitorBound

Type: Enhancement
Component: hotspot
Sub-Component: runtime
Affected Version: 14

Priority: P4
Status: Resolved
Resolution: Fixed
OS: generic
CPU: generic

Submitted: 2019-09-13
Updated: 2019-09-26
Resolved: 2019-09-13

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JDK 14
14 b15Fixed

The product flag, MonitorBound, was added in JDK 7-B99 by JDK-6852873.
It was also backported to various JDK6 update releases. The flag was added
as a way to control how often the system invoked a cleanup safepoint for
reducing the number of idle ObjectMonitors. 

An experimental flag MonitorUsedDeflationThreshold was added in JDK 10-B21
by JDK-8181859 to control when idle monitor deflation is invoked. The new flag
is described:

  experimental(intx, MonitorUsedDeflationThreshold, 90, \
                "Percentage of used monitors before triggering cleanup "  \
                "safepoint which deflates monitors (0 is off). " \
                "The check is performed on GuaranteedSafepointInterval.") \
                range(0, 100)

A policy based on the percentage of used monitors is a more flexible
mechanism that the fixed limit specified by MonitorBound. The MonitorBound
option should have been deprecated back in JDK 10, but we missed that
detail.

CSR :	JDK-8230939 - Deprecate MonitorBound
Relates :	JDK-6852873 - Increase in delta between application stopped time and ParNew GC time over application lifetime
Relates :	JDK-8230940 - Obsolete MonitorBound
Relates :	JDK-8181859 - Monitor deflation is not checked in cleanup path