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8341060: Cleanup statics in HeapDumper #21216

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8341060: Cleanup statics in HeapDumper #21216

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alexmenkov Sep 27, 2024
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alexmenkov Sep 27, 2024
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101 changes: 37 additions & 64 deletions src/hotspot/share/services/heapDumper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1512,6 +1512,38 @@ class ClassDumper : public KlassClosure {
}
};

// Support class used to generate HPROF_LOAD_CLASS records

class LoadedClassDumper : public LockedClassesDo {
private:
AbstractDumpWriter* _writer;
GrowableArray<Klass*>* _klass_map;
Comment on lines +1519 to +1520
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While we are at it, turn these const?

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the map is updated by the class, so it can't be const

u4 _class_serial_num;
AbstractDumpWriter* writer() const { return _writer; }
void add_class_serial_number(Klass* k, int serial_num) {
_klass_map->at_put_grow(serial_num, k);
}
public:
LoadedClassDumper(AbstractDumpWriter* writer, GrowableArray<Klass*>* klass_map)
: _writer(writer), _klass_map(klass_map), _class_serial_num(0) {}

void do_klass(Klass* k) {
// len of HPROF_LOAD_CLASS record
u4 remaining = 2 * oopSize + 2 * sizeof(u4);
DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining);
// class serial number is just a number
writer()->write_u4(++_class_serial_num);
// class ID
writer()->write_classID(k);
// add the Klass* and class serial number pair
add_class_serial_number(k, _class_serial_num);
writer()->write_u4(STACK_TRACE_ID);
// class name ID
Symbol* name = k->name();
writer()->write_symbolID(name);
}
};

// Support class used to generate HPROF_GC_ROOT_JNI_LOCAL records

class JNILocalsDumper : public OopClosure {
Expand Down Expand Up @@ -2190,9 +2222,7 @@ void DumpMerger::do_merge() {
// The VM operation that performs the heap dump
class VM_HeapDumper : public VM_GC_Operation, public WorkerTask, public UnmountedVThreadDumper {
private:
static VM_HeapDumper* _global_dumper;
static DumpWriter* _global_writer;
DumpWriter* _local_writer;
DumpWriter* _writer;
JavaThread* _oome_thread;
Method* _oome_constructor;
bool _gc_before_heap_dump;
Expand All @@ -2218,33 +2248,13 @@ class VM_HeapDumper : public VM_GC_Operation, public WorkerTask, public Unmounte
return Atomic::fetch_then_add(&_dump_seq, 1);
}

// accessors and setters
static VM_HeapDumper* dumper() { assert(_global_dumper != nullptr, "Error"); return _global_dumper; }
static DumpWriter* writer() { assert(_global_writer != nullptr, "Error"); return _global_writer; }

void set_global_dumper() {
assert(_global_dumper == nullptr, "Error");
_global_dumper = this;
}
void set_global_writer() {
assert(_global_writer == nullptr, "Error");
_global_writer = _local_writer;
}
void clear_global_dumper() { _global_dumper = nullptr; }
void clear_global_writer() { _global_writer = nullptr; }
DumpWriter* writer() const { return _writer; }

bool skip_operation() const;

// writes a HPROF_LOAD_CLASS record to global writer
static void do_load_class(Klass* k);

// HPROF_GC_ROOT_THREAD_OBJ records for platform and mounted virtual threads
void dump_threads(AbstractDumpWriter* writer);

void add_class_serial_number(Klass* k, int serial_num) {
_klass_map->at_put_grow(serial_num, k);
}

bool is_oom_thread(JavaThread* thread) const {
return thread == _oome_thread && _oome_constructor != nullptr;
}
Expand All @@ -2259,7 +2269,7 @@ class VM_HeapDumper : public VM_GC_Operation, public WorkerTask, public Unmounte
0 /* total full collections, dummy, ignored */,
gc_before_heap_dump),
WorkerTask("dump heap") {
_local_writer = writer;
_writer = writer;
_gc_before_heap_dump = gc_before_heap_dump;
_klass_map = new (mtServiceability) GrowableArray<Klass*>(INITIAL_CLASS_COUNT, mtServiceability);

Expand Down Expand Up @@ -2313,9 +2323,6 @@ class VM_HeapDumper : public VM_GC_Operation, public WorkerTask, public Unmounte
void dump_vthread(oop vt, AbstractDumpWriter* segment_writer);
};

VM_HeapDumper* VM_HeapDumper::_global_dumper = nullptr;
DumpWriter* VM_HeapDumper::_global_writer = nullptr;

bool VM_HeapDumper::skip_operation() const {
return false;
}
Expand All @@ -2329,31 +2336,6 @@ void DumperSupport::end_of_dump(AbstractDumpWriter* writer) {
writer->write_u4(0);
}

// writes a HPROF_LOAD_CLASS record for the class
void VM_HeapDumper::do_load_class(Klass* k) {
static u4 class_serial_num = 0;

// len of HPROF_LOAD_CLASS record
u4 remaining = 2*oopSize + 2*sizeof(u4);

DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining);

// class serial number is just a number
writer()->write_u4(++class_serial_num);

// class ID
writer()->write_classID(k);

// add the Klass* and class serial number pair
dumper()->add_class_serial_number(k, class_serial_num);

writer()->write_u4(STACK_TRACE_ID);

// class name ID
Symbol* name = k->name();
writer()->write_symbolID(name);
}

// Write a HPROF_GC_ROOT_THREAD_OBJ record for platform/carrier and mounted virtual threads.
// Then walk the stack so that locals and JNI locals are dumped.
void VM_HeapDumper::dump_threads(AbstractDumpWriter* writer) {
Expand Down Expand Up @@ -2430,11 +2412,6 @@ void VM_HeapDumper::doit() {
}
}

// At this point we should be the only dumper active, so
// the following should be safe.
set_global_dumper();
set_global_writer();

WorkerThreads* workers = ch->safepoint_workers();
prepare_parallel_dump(workers);

Expand All @@ -2446,10 +2423,6 @@ void VM_HeapDumper::doit() {
workers->run_task(this, _num_dumper_threads);
_poi = nullptr;
}

// Now we clear the global variables, so that a future dumper can run.
clear_global_dumper();
clear_global_writer();
}

void VM_HeapDumper::work(uint worker_id) {
Expand Down Expand Up @@ -2480,8 +2453,8 @@ void VM_HeapDumper::work(uint worker_id) {

// write HPROF_LOAD_CLASS records
{
LockedClassesDo locked_load_classes(&do_load_class);
ClassLoaderDataGraph::classes_do(&locked_load_classes);
LoadedClassDumper loaded_class_dumper(writer(), _klass_map);
ClassLoaderDataGraph::classes_do(&loaded_class_dumper);
}

// write HPROF_FRAME and HPROF_TRACE records
Expand Down