AppContext.getProperty() uses poorly-scaling System.getProperty inside

[alexbudarov]

Environment

• Platform version: 6.8.12

Description of the bug or enhancement

Have been performing performance testing with JVisualVM.
One of CPU profile method chains shows interesting info:

AppContext.getProperty() uses System.getProperty() inside.
But System.getProperty() is implemented via Hashtable class. Every get() call enters a global synchronized block and therefore is poorly scalable in multithread environment.

I think that all platform code assumes that AppContext.getProperty() is cheap and highly scalable. So depending on System.getProperty() is a problem.

[knstvk]

Solution

System properties are read on startup and cached in a ConcurrentHashMap. Consequently, changes in system properties made at runtime do not affect the system. If you need to read the new value of a system property, reset the cache using the clearSystemPropertiesCache() methods of the CachingFacadeMBean JMX beans available in the core and web modules.

[knstvk]

For manual testing: try to redefine an app property with a system property.