Incorporate feedback/suggestion from David Holmes:

- Change the flag to be expressed as the number of 10ms chunks (i.e. number of wait attempts) to wait.
- Limit the max allowed wait to 10s. That's 1000 wait attempts with each attempt=10ms.

src/hotspot/share/runtime/globals.hpp

@@ -835,10 +835,12 @@ const int ObjectAlignmentInBytes = 8;
           "JVM aborts, producing an error log and core/mini dump, on the "  \
           "first occurrence of an out-of-memory error thrown from JVM")     \
                                                                             \
-  product(intx, WaitUserThreadAtExitTimeout, 300,                           \
-          "Maximum delay in milliseconds at exit waiting for user threads " \
-          "in native")                                                      \
-          range(0, max_intx)                                                \
+  product(intx, UserThreadWaitAttemptsAtExit, 30,                           \
+          "Number of attempts waiting for user threads in native during "   \
+          "JVM exit. Each wait attempt is 10-millisecond. The max allowed " \
+          "wait attempts for user threads in native is 1000, which is "     \
+          "10 seconds.")                                                    \
+          range(0, 1000)                                                    \
                                                                             \
   /* tracing */                                                             \
                                                                             \

src/hotspot/share/runtime/vmOperations.cpp

@@ -392,8 +392,7 @@ int VM_Exit::wait_for_threads_in_native_to_block() {
   // better to terminate VM when current thread is the only active thread, so
   // wait for user threads too. Numbers are in 10 milliseconds.
   int wait_time_per_attempt = 10;                 // in milliseconds
-  int max_wait_attempts_user_thread =
-                  WaitUserThreadAtExitTimeout / wait_time_per_attempt;
+  int max_wait_attempts_user_thread = UserThreadWaitAttemptsAtExit;
   int max_wait_attempts_compiler_thread = 1000; // at least 10 seconds
 
   int attempts = 0;