8357828: Add a timestamp to jcmd diagnostic commands

src/hotspot/share/runtime/threads.cpp

@@ -1344,13 +1344,11 @@ class PrintOnClosure : public ThreadClosure {
 void Threads::print_on(outputStream* st, bool print_stacks,
                        bool internal_format, bool print_concurrent_locks,
                        bool print_extended_info) {
-  char buf[32];
-  st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
-
   st->print_cr("Full thread dump %s (%s %s)",
                VM_Version::vm_name(),
                VM_Version::vm_release(),
                VM_Version::vm_info_string());
+  char buf[32];
   JDK_Version::current().to_string(buf, sizeof(buf));
   const char* runtime_name = JDK_Version::runtime_name() != nullptr ?
                              JDK_Version::runtime_name() : "";

src/hotspot/share/services/diagnosticCommand.cpp

@@ -183,6 +183,12 @@ static int compare_strings(const char** s1, const char** s2) {
   return ::strcmp(*s1, *s2);
 }
 
+static void print_local_time(outputStream* output) {
+  char buf[32];
+  output->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
+}
+
+
 void HelpDCmd::execute(DCmdSource source, TRAPS) {
   if (_all.value()) {
     GrowableArray<const char*>* cmd_list = DCmdFactory::DCmd_list(source);
@@ -250,6 +256,7 @@ PrintVMFlagsDCmd::PrintVMFlagsDCmd(outputStream* output, bool heap) :
 }
 
 void PrintVMFlagsDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   if (_all.value()) {
     JVMFlag::printFlags(output(), true);
   } else {
@@ -398,6 +405,7 @@ void VMUptimeDCmd::execute(DCmdSource source, TRAPS) {
 }
 
 void VMInfoDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   VMError::print_vm_info(_output);
 }
 
@@ -414,11 +422,13 @@ void RunFinalizationDCmd::execute(DCmdSource source, TRAPS) {
 }
 
 void HeapInfoDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   MutexLocker hl(THREAD, Heap_lock);
   Universe::heap()->print_heap_on(output());
 }
 
 void FinalizerInfoDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   ResourceMark rm(THREAD);
 
   if (!InstanceKlass::is_finalization_enabled()) {
@@ -492,6 +502,7 @@ HeapDumpDCmd::HeapDumpDCmd(outputStream* output, bool heap) :
 }
 
 void HeapDumpDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   jlong level = -1; // -1 means no compression.
   jlong parallel = HeapDumper::default_num_of_dump_threads();
 
@@ -539,6 +550,7 @@ ClassHistogramDCmd::ClassHistogramDCmd(outputStream* output, bool heap) :
 }
 
 void ClassHistogramDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   jlong num = _parallel_thread_num.value();
   if (num < 0) {
     output()->print_cr("Parallel thread number out of range (>=0): " JLONG_FORMAT, num);
@@ -564,6 +576,7 @@ ThreadDumpDCmd::ThreadDumpDCmd(outputStream* output, bool heap) :
 }
 
 void ThreadDumpDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   // thread stacks and JNI global handles
   VM_PrintThreads op1(output(), _locks.value(), _extended.value(), true /* print JNI handle info */);
   VMThread::execute(&op1);
@@ -801,6 +814,7 @@ JMXStatusDCmd::JMXStatusDCmd(outputStream *output, bool heap_allocated) :
 }
 
 void JMXStatusDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   ResourceMark rm(THREAD);
   HandleMark hm(THREAD);
 
@@ -834,20 +848,24 @@ VMDynamicLibrariesDCmd::VMDynamicLibrariesDCmd(outputStream *output, bool heap_a
 }
 
 void VMDynamicLibrariesDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   os::print_dll_info(output());
   output()->cr();
 }
 
 void CompileQueueDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   VM_PrintCompileQueue printCompileQueueOp(output());
   VMThread::execute(&printCompileQueueOp);
 }
 
 void CodeListDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   CodeCache::print_codelist(output());
 }
 
 void CodeCacheDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   CodeCache::print_layout(output());
 }
 
@@ -874,6 +892,7 @@ CodeHeapAnalyticsDCmd::CodeHeapAnalyticsDCmd(outputStream* output, bool heap) :
 }
 
 void CodeHeapAnalyticsDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   jlong granularity = _granularity.value();
   if (granularity < 1) {
     Exceptions::fthrow(THREAD_AND_LOCATION, vmSymbols::java_lang_IllegalArgumentException(),
@@ -895,6 +914,7 @@ EventLogDCmd::EventLogDCmd(outputStream* output, bool heap) :
 }
 
 void EventLogDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   int max = (int)_max.value();
   if (max < 0) {
     output()->print_cr("Invalid max option: \"%d\".", max);
@@ -909,6 +929,7 @@ void EventLogDCmd::execute(DCmdSource source, TRAPS) {
 }
 
 void CompilerDirectivesPrintDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   DirectivesStack::print(output());
 }
 
@@ -929,6 +950,7 @@ void CompilerDirectivesRemoveDCmd::execute(DCmdSource source, TRAPS) {
 void CompilerDirectivesClearDCmd::execute(DCmdSource source, TRAPS) {
   DirectivesStack::clear();
 }
+
 #if INCLUDE_SERVICES
 ClassHierarchyDCmd::ClassHierarchyDCmd(outputStream* output, bool heap) :
                                        DCmdWithParser(output, heap),
@@ -945,6 +967,7 @@ ClassHierarchyDCmd::ClassHierarchyDCmd(outputStream* output, bool heap) :
 }
 
 void ClassHierarchyDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   VM_PrintClassHierarchy printClassHierarchyOp(output(), _print_interfaces.value(),
                                                _print_subclasses.value(), _classname.value());
   VMThread::execute(&printClassHierarchyOp);
@@ -982,6 +1005,7 @@ class VM_PrintClasses : public VM_Operation {
 };
 
 void ClassesDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   VM_PrintClasses vmop(output(), _verbose.value());
   VMThread::execute(&vmop);
 }
@@ -1000,6 +1024,7 @@ DumpSharedArchiveDCmd::DumpSharedArchiveDCmd(outputStream* output, bool heap) :
 }
 
 void DumpSharedArchiveDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   jboolean is_static;
   const char* scmd = _suboption.value();
 
@@ -1140,10 +1165,12 @@ static void execute_vthread_command(Symbol* method_name, outputStream* output, T
 }
 
 void VThreadSchedulerDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   execute_vthread_command(vmSymbols::printScheduler_name(), output(), CHECK);
 }
 
 void VThreadPollersDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   execute_vthread_command(vmSymbols::printPollers_name(), output(), CHECK);
 }
 
@@ -1158,6 +1185,7 @@ CompilationMemoryStatisticDCmd::CompilationMemoryStatisticDCmd(outputStream* out
 }
 
 void CompilationMemoryStatisticDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   const size_t minsize = _minsize.has_value() ? _minsize.value()._size : 0;
   CompilationMemoryStatistic::print_jcmd_report(output(), _verbose.value(), _legend.value(), minsize);
 }
@@ -1167,6 +1195,7 @@ void CompilationMemoryStatisticDCmd::execute(DCmdSource source, TRAPS) {
 SystemMapDCmd::SystemMapDCmd(outputStream* output, bool heap) : DCmd(output, heap) {}
 
 void SystemMapDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   MemMapPrinter::print_all_mappings(output());
 }
 
@@ -1179,6 +1208,7 @@ SystemDumpMapDCmd::SystemDumpMapDCmd(outputStream* output, bool heap) :
 }
 
 void SystemDumpMapDCmd::execute(DCmdSource source, TRAPS) {
+  print_local_time(output());
   const char* name = _filename.value();
   if (name == nullptr || name[0] == 0) {
     output()->print_cr("filename is empty or not specified.  No file written");

test/hotspot/jtreg/serviceability/dcmd/compiler/CodeCacheTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -113,6 +113,7 @@ public void run(CommandExecutor executor) {
         // Get output from dcmd (diagnostic command)
         OutputAnalyzer output = executor.execute("Compiler.codecache");
         Iterator<String> lines = output.asLines().iterator();
+        lines.next(); // skip timestamp
 
         // Validate code cache segments
         String line;

test/hotspot/jtreg/serviceability/dcmd/vm/ClassHierarchyTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -54,15 +54,18 @@ public class ClassHierarchyTest {
     // |--DcmdTestClass$$Lambda/4081552/0xa529fbb0
 
     // > VM.class_hierarchy DcmdBaseClass
+    // 2025-01-01 10:59:59
     // java.lang.Object/null
     // |--DcmdBaseClass/0xa4abcd48
 
     // > VM.class_hierarchy DcmdBaseClass -s
+    // 2025-01-01 10:59:59
     // java.lang.Object/null
     // |--DcmdBaseClass/0xa4abcd48
     // |  |--DcmdTestClass/0xa4abcd48
 
     // > VM.class_hierarchy DcmdBaseClass -i -s
+    // 2025-01-01 10:59:59
     // java.lang.Object/null
     // |--DcmdBaseClass/0xa4abcd48
     // |  implements Intf2/0xa4abcd48 (declared intf)
@@ -111,13 +114,14 @@ public void run(CommandExecutor executor) throws ClassNotFoundException {
         // Verify the output for the simple hierachry of just DcmdBaseClass.
         output = executor.execute("VM.class_hierarchy DcmdBaseClass");
         lines = output.asLines().iterator();
+        lines.next(); // skip timestamp
         i = 0;
         while (lines.hasNext()) {
             String line = lines.next();
             Matcher m = expected_lines[i].matcher(line);
             i++;
             if (!m.matches()) {
-                Assert.fail("Failed to match line #" + i + ": " + line);
+                Assert.fail("Failed. Expected line #%d \"%s\" to match \"%s\"".formatted(i, line, expected_lines[i].pattern()));
             }
             // Should only be two lines of output in this form.
             if (i == 2) break;
@@ -130,13 +134,14 @@ public void run(CommandExecutor executor) throws ClassNotFoundException {
         // Verify the output for the full hierarchy of DcmdBaseClass, but without interfaces.
         output = executor.execute("VM.class_hierarchy DcmdBaseClass -s");
         lines = output.asLines().iterator();
+        lines.next(); // skip timestamp
         i = 0;
         while (lines.hasNext()) {
             String line = lines.next();
             Matcher m = expected_lines[i].matcher(line);
             i++;
             if (!m.matches()) {
-                Assert.fail("Failed to match line #" + i + ": " + line);
+                Assert.fail("Failed. Expected line #%d \"%s\" to match \"%s\"".formatted(i, line, expected_lines[i].pattern()));
             }
             // "implements" lines should not be in this output.
             if (i == 2 || i == 4) i += 2;
@@ -149,6 +154,7 @@ public void run(CommandExecutor executor) throws ClassNotFoundException {
         // Verify the output for the full hierarchy of DcmdBaseClass, including interfaces.
         output = executor.execute("VM.class_hierarchy DcmdBaseClass -i -s");
         lines = output.asLines().iterator();
+        lines.next(); // skip timestamp
         i = 0;
         String classLoaderAddr = null;
         while (lines.hasNext()) {