RFR: 8369238: Allow virtual thread preemption on some common class initialization paths [v2]

[Patricio Chilano Mateo]

On Thu, 16 Oct 2025 07:15:33 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

>> Right, it should be walked as a heap frame. Could you verify if this patch fixes the issue?
>> 
>> 
>> diff --git a/src/hotspot/share/runtime/continuationFreezeThaw.cpp b/src/hotspot/share/runtime/continuationFreezeThaw.cpp
>> index 86c56fe583f..fb1f66c60f4 100644
>> --- a/src/hotspot/share/runtime/continuationFreezeThaw.cpp
>> +++ b/src/hotspot/share/runtime/continuationFreezeThaw.cpp
>> @@ -196,7 +196,7 @@ static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, output
>>  static void log_frames(JavaThread* thread, bool dolog = true);
>>  static void log_frames_after_thaw(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp);
>>  static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st = tty);
>> -static void verify_frame_kind(const frame& top, Continuation::preempt_kind preempt_kind, Method** m_ptr = nullptr, const char** code_name_ptr = nullptr, int* bci_ptr = nullptr);
>> +static void verify_frame_kind(frame& top, Continuation::preempt_kind preempt_kind, Method** m_ptr = nullptr, const char** code_name_ptr = nullptr, int* bci_ptr = nullptr, stackChunkOop chunk = nullptr);
>> 
>>  #define assert_pfl(p, ...) \
>>  do {                                           \
>> @@ -1723,7 +1723,7 @@ bool FreezeBase::check_valid_fast_path() {
>>    return true;
>>  }
>> 
>> -static void verify_frame_kind(const frame& top, Continuation::preempt_kind preempt_kind, Method** m_ptr, const char** code_name_ptr, int* bci_ptr) {
>> +static void verify_frame_kind(frame& top, Continuation::preempt_kind preempt_kind, Method** m_ptr, const char** code_name_ptr, int* bci_ptr, stackChunkOop chunk) {
>>    Method* m;
>>    const char* code_name;
>>    int bci;
>> @@ -1747,7 +1747,13 @@ static void verify_frame_kind(const frame& top, Continuation::preempt_kind preem
>>        RegisterMap reg_map(current,
>>                    RegisterMap::UpdateMap::skip,
>>                    RegisterMap::ProcessFrames::skip,
>> -                  RegisterMap::WalkContinuation::skip);
>> +                  RegisterMap::WalkContinuation::include);
>> +      if (top.is_heap_frame()) {
>> +        assert(chunk != nullptr, "");
>> +        reg_map.set_stack_chunk(chunk);
>> +        top = chunk->relativize(top);
>> +        top.set_frame_index(0);
>> +      }
>>        frame fr = top.sender(&reg_map);
>>        vframe*  vf  = vframe::new_vframe(&fr, &reg_map, current);
>>        compiledVFrame* cvf = compiledVFrame::cast(vf);
>> @@ -1803,7 +1809,7 @@ static void log_preempt_after_freeze(...
>
> Your patch fixes the issue. Thanks!

Great, pushed fix.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27802#discussion_r2436600849