StagingPermissionCheckerFactory should use ServiceTracker to track highest ranking PermissionCheckerFactory service to avoid repeatedly lookup service registry causing global synchronized point

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.0.0 DXP FP5, 7.0.0 DXP SP1, 7.0.3 CE GA4, 7.1.X, Master
• Component/s: Application Security, Performance, Staging
• Labels:
  • liferay-digital-enterprise-70-sp1
  • liferay-fixpack-de-5-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Story Points: 1
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/43179

Search "- waiting to lock <0x0000000722fb2be0> (a java.util.HashMap)" in the attached thread dump, you will see many threads are blocked waiting to access service registry due to StagingPermissionCheckerFactory repeatedly lookup the current services.

In case like this, it should use ServiceTracker, which has an internal cache for top ranking service, to avoid unnecessary service registry lookup.