New CML option to ajust the extra number of startup hints that can be stored into the shared cache.

[hangshao0]

Issue or pull request number:
eclipse-openj9/openj9#20366

Overview:
Previously, there is no limit on the number of startup hints that can be stored into the shared cache. As long as the shared cache is not full/soft full, new startup hints can be stored. However, there could be applications that aggressively store a large number of startup hints that filled up the shared cache. No other data can be stored anymore.

eclipse-openj9/openj9#20366 introduces a limit on the additional number (which is 64 by default) of startup hints that can be stored into a shared cache. An command line utility option is added to adjust this number (see below).

User can use -Xshareclasses:printStats=startuphint or -Xshareclasses:printDetails to check how many startup hints are already stored and how many more can be stored in the shared cache.

Release target:
Eclipse OpenJ9 0.49.0

Applies to the following JDK versions:
All versions

Applies to the following platforms:
All platforms

For new command line options:

• Option name and syntax: -Xshareclasses:extraStartupHints=<number>
• If values are set:
  <number> should be an integer >=0.
• Purpose:
  By default, a shared cache allows at most 64 startup hints to be stored. This count is decremented by 1 after 1 startup hints is stored. No more hints can be stored once it reaches 0. User can use -Xshareclasses:extraStartupHints=<number> to adjust this count as needed. e.g. -Xshareclasses:extraStartupHints=0 prevents any new hints to be stored. -Xshareclasses:extraStartupHints=10 allows 10 more new hints to be stored.
• Restrictions: N.A.