src/share/vm/services/diagnosticFramework.hpp

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rev 3388 : imported patch dcmd-fixes

@@ -236,10 +236,20 @@
   }
 
   static const char* name() { return "No Name";}
   static const char* description() { return "No Help";}
   static const char* disabled_message() { return "Diagnostic command currently disabled"; }
+  // The impact() method returns a description of the intrusiveness of the diagnostic
+  // command on the Java Virtual Machine behavior. The rational for this method is that some
+  // diagnostic commands can seriously disrupt the behavior of the Java Virtual Machine
+  // (for instance a Thread Dump for an application with several tens of thousands of threads,
+  // or a Head Dump with a 40GB+ heap size) and other diagnostic commands have no serious
+  // impact on the JVM (for instance, getting the command line arguments or the JVM version).
+  // The recommended format for the description is <impact level>: [longer description],
+  // where the impact level is selected among this list: {Low, Medium, High}. The optional
+  // longer description can provide more specific details like the fact that Thread Dump
+  // impact depends on the heap size.
   static const char* impact() { return "Low: No impact"; }
   static int num_arguments() { return 0; }
   outputStream* output() { return _output; }
   bool is_heap_allocated()  { return _is_heap_allocated; }
   virtual void print_help(const char* name) {

@@ -248,11 +258,11 @@
   virtual void parse(CmdLine* line, char delim, TRAPS) {
     DCmdArgIter iter(line->args_addr(), line->args_len(), delim);
     bool has_arg = iter.next(CHECK);
     if (has_arg) {
       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
-                "Unknown argument in diagnostic command");
+                "Argument list of diagnostic command should be empty.");
     }
   }
   virtual void execute(TRAPS) { }
   virtual void reset(TRAPS) { }
   virtual void cleanup() { }