8233850: Shenandoah: Shenandoah thread count ergonomics should be container aware

Reviewed-by: rkennke

Author: zhengyu123

src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp

@@ -71,7 +71,7 @@ void ShenandoahArguments::initialize() {
   // compromise here.
   bool ergo_conc = FLAG_IS_DEFAULT(ConcGCThreads);
   if (ergo_conc) {
-    FLAG_SET_DEFAULT(ConcGCThreads, MAX2(1, os::processor_count() / 4));
+    FLAG_SET_DEFAULT(ConcGCThreads, MAX2(1, os::initial_active_processor_count() / 4));
   }
 
   if (ConcGCThreads == 0) {
@@ -85,7 +85,7 @@ void ShenandoahArguments::initialize() {
   // the number of concurrent threads.
   bool ergo_parallel = FLAG_IS_DEFAULT(ParallelGCThreads);
   if (ergo_parallel) {
-    FLAG_SET_DEFAULT(ParallelGCThreads, MAX2(1, os::processor_count() / 2));
+    FLAG_SET_DEFAULT(ParallelGCThreads, MAX2(1, os::initial_active_processor_count() / 2));
   }
 
   if (ParallelGCThreads == 0) {