--- old/src/hotspot/os/aix/os_aix.cpp	2017-10-11 14:34:29.392172495 -0400
+++ new/src/hotspot/os/aix/os_aix.cpp	2017-10-11 14:34:28.176103209 -0400
@@ -3624,6 +3624,14 @@
 };
 
 int os::active_processor_count() {
+  // User has overridden the number of active processors
+  if (ActiveProcessorCount > 0) {
+    log_trace(os)("active_processor_count: "
+                  "active processor count set by user : %d",
+                  (int)ActiveProcessorCount);
+    return ActiveProcessorCount;
+  }
+
   int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
   assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
   return online_cpus;