8280844: Epoch shift synchronization point for Compiler threads is inadequate

Reviewed-by: egahlin

Author: Markus Grönlund

make/src/classes/build/tools/jfr/GenerateJfrFiles.java

@@ -739,7 +739,6 @@ private static void printJfrEventClassesHpp(Metadata metadata, File outputFile)
             out.write("#include \"utilities/ticks.hpp\"");
             out.write("#if INCLUDE_JFR");
             out.write("#include \"jfr/recorder/service/jfrEvent.hpp\"");
-            out.write("#include \"jfr/support/jfrEpochSynchronization.hpp\"");
             out.write("/*");
             out.write(" * Each event class has an assert member function verify() which is invoked");
             out.write(" * just before the engine writes the event and its fields to the data stream.");
@@ -869,10 +868,6 @@ private static void printWriteData(Printer out, TypeElement type) {
         if (type.isEvent && type.internal) {
             out.write("    JfrEventSetting::unhide_internal_types();");
         }
-        if (("_thread_in_native").equals(type.commitState)) {
-            out.write("    // explicit epoch synchronization check");
-            out.write("    JfrEpochSynchronization sync;");
-        }
         for (FieldElement field : type.fields) {
             if (field.struct) {
                 out.write("    _" + field.name + ".writeData(w);");

src/hotspot/share/compiler/compilerEvent.cpp

@@ -27,7 +27,9 @@
 #include "jfr/jfr.hpp"
 #include "jfr/jfrEvents.hpp"
 #include "jfr/metadata/jfrSerializer.hpp"
+#include "runtime/interfaceSupport.inline.hpp"
 #include "runtime/semaphore.inline.hpp"
+#include "runtime/thread.inline.hpp"
 #include "utilities/growableArray.hpp"
 
 // Synchronizes access to phases_names.
@@ -114,6 +116,16 @@ int CompilerEvent::PhaseEvent::get_phase_id(const char* phase_name, bool may_exi
   return index;
 }
 
+// As part of event commit, a Method* is tagged as a function of an epoch.
+// Epochs evolve during safepoints. To ensure the event is tagged in the correct epoch,
+// that is, to avoid a race, the thread will participate in the safepoint protocol
+// by transitioning from _thread_in_native to _thread_in_vm.
+template <typename EventType>
+static inline void commit(EventType& event) {
+  ThreadInVMfromNative transition(JavaThread::current());
+  event.commit();
+ }
+
 void CompilerEvent::CompilationEvent::post(EventCompilation& event, int compile_id, CompilerType compiler_type, Method* method, int compile_level, bool success, bool is_osr, int code_size, int inlined_bytecodes) {
   event.set_compileId(compile_id);
   event.set_compiler(compiler_type);
@@ -123,7 +135,7 @@ void CompilerEvent::CompilationEvent::post(EventCompilation& event, int compile_
   event.set_isOsr(is_osr);
   event.set_codeSize(code_size);
   event.set_inlinedBytes(inlined_bytecodes);
-  event.commit();
+  commit(event);
 }
 
 void CompilerEvent::CompilationFailureEvent::post(EventCompilationFailure& event, int compile_id, const char* reason) {
@@ -147,7 +159,7 @@ void CompilerEvent::InlineEvent::post(EventCompilerInlining& event, int compile_
   event.set_succeeded(success);
   event.set_message(msg);
   event.set_bci(bci);
-  event.commit();
+  commit(event);
 }
 
 void CompilerEvent::InlineEvent::post(EventCompilerInlining& event, int compile_id, Method* caller, Method* callee, bool success, const char* msg, int bci) {

src/hotspot/share/jfr/metadata/metadata.xml

@@ -558,7 +558,7 @@
     <Field type="ulong" contentType="bytes" name="used" label="Used" />
   </Event>
 
-  <Event name="Compilation" category="Java Virtual Machine, Compiler" label="Compilation" thread="true" commitState="_thread_in_native">
+  <Event name="Compilation" category="Java Virtual Machine, Compiler" label="Compilation" thread="true">
     <Field type="uint" name="compileId" label="Compilation Identifier" relation="CompileId" />
     <Field type="CompilerType" name="compiler" label="Compiler" />
     <Field type="Method" name="method" label="Method" />
@@ -586,7 +586,7 @@
     <Field type="string" name="descriptor" label="Method Descriptor" />
   </Type>
 
-  <Event name="CompilerInlining" category="Java Virtual Machine, Compiler, Optimization" label="Method Inlining" thread="true" startTime="false" commitState="_thread_in_native">
+  <Event name="CompilerInlining" category="Java Virtual Machine, Compiler, Optimization" label="Method Inlining" thread="true" startTime="false">
     <Field type="uint" name="compileId" label="Compilation Identifier" relation="CompileId" />
     <Field type="Method" name="caller" label="Caller Method" />
     <Field type="CalleeMethod" name="callee" struct="true" label="Callee Method" />

src/hotspot/share/jfr/metadata/metadata.xsd

@@ -72,7 +72,6 @@
               <xs:attribute name="period" type="periodType" use="optional" />
               <xs:attribute name="cutoff" type="xs:boolean" use="optional" />
               <xs:attribute name="throttle" type="xs:boolean" use="optional" />
-              <xs:attribute name="commitState" type="xs:string" use="optional" />
             </xs:complexType>
           </xs:element>
           <xs:element maxOccurs="unbounded" name="Type">