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traces and fixes

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This commit is contained in:
tstuefe 2026-01-16 15:31:58 +01:00
parent d7c5c529c5
commit 592606e9cf
3 changed files with 144 additions and 25 deletions
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119
src/hotspot/share/jfr/leakprofiler/chains/dfsClosure.cpp
View File

@ -38,6 +38,47 @@
#include "utilities/debug.hpp"
#include "utilities/stack.inline.hpp"
#include <stdio.h>
#define TRC(msg) { \
if (UseNewCode) { \
printf(msg); \
printf("\n"); \
fflush(stdout); \
} \
}
#define TRCFMT(format, ...) { \
if (UseNewCode) { \
printf(format, __VA_ARGS__); \
printf("\n"); \
fflush(stdout); \
} \
}
#define TRCOOP(prefix, o) { \
if (UseNewCode) { \
char txt[1024]; \
stringStream ss(txt, sizeof(txt)); \
o->klass()->name()->print_value_on(&ss); \
printf("%s: " PTR_FORMAT " %s ", prefix, p2i(o), txt); \
printf("\n"); \
fflush(stdout); \
} \
}
#define TRCOOPFMT(prefix, o, format, ...) { \
if (UseNewCode) { \
char txt[1024]; \
stringStream ss(txt, sizeof(txt)); \
o->klass()->name()->print_value_on(&ss); \
printf("%s: " PTR_FORMAT " %s ", prefix, p2i(o), txt); \
printf(format, __VA_ARGS__); \
printf("\n"); \
fflush(stdout); \
} \
}
UnifiedOopRef DFSClosure::_reference_stack[max_dfs_depth];
void DFSClosure::find_leaks_from_edge(EdgeStore* edge_store,
@ -58,6 +99,8 @@ void DFSClosure::find_leaks_from_root_set(EdgeStore* edge_store,
assert(edge_store != nullptr, "invariant");
assert(mark_bits != nullptr, "invariant");
TRC("SCANNING ROOTS");
// Mark root set, to avoid going sideways
DFSClosure dfs(edge_store, mark_bits, nullptr);
dfs._max_depth = 1;
@ -65,11 +108,18 @@ void DFSClosure::find_leaks_from_root_set(EdgeStore* edge_store,
rs.process();
dfs.drain_probe_stack();
TRC("DONE SCANNING ROOTS");
TRC("SCANNING DEEP");
// Depth-first search
dfs._max_depth = max_dfs_depth;
dfs._ignore_root_set = true;
rs.process();
dfs.drain_probe_stack();
TRC("DONE SCANNING DEPP");
}
// A sanity limit to avoid runaway memory scenarios for pathological
@ -100,14 +150,28 @@ DFSClosure::~DFSClosure() {
}
#endif // ASSERT
void DFSClosure::push_to_probe_stack(UnifiedOopRef ref, int chunkindex) {
if (_probe_stack.is_full()) {
void DFSClosure::push_to_probe_stack(UnifiedOopRef ref, oop pointee, size_t depth, int chunkindex) {
if (pointee == nullptr) {
// Don't push null references
return;
}
const unsigned newdepth =
_current_item == nullptr ? 0 : checked_cast<unsigned>(_current_item->depth + 1);
ProbeStackItem item { ref, newdepth, chunkindex };
if (depth > 0 && pointee_was_visited(pointee)) {
// Don't push oops we already visited (exception: root oops)
return;
}
if (_probe_stack.is_full()) {
// Probe stack exhausted; see remarks about probe stack max depth above.
return;
}
ProbeStackItem item { ref, checked_cast<unsigned>(depth), chunkindex };
_probe_stack.push(item);
TRCOOPFMT("pushed", pointee, "path depth %u, probestack depth %zu", item.depth, _probe_stack.size());
}
void DFSClosure::handle_oop() {
@ -116,10 +180,10 @@ void DFSClosure::handle_oop() {
const oop pointee = current_pointee();
const size_t depth = current_depth();
assert(depth < _max_depth, "Sanity");
assert(depth < _max_depth, "Sanity (%zu)", depth);
if (UseNewCode) printf(PTR_FORMAT ", depth %zu\n", p2i(pointee), depth);
TRCOOPFMT("popped", pointee, "path depth %zu, probestack depth %zu", depth, _probe_stack.size());
if (depth == 0 && _ignore_root_set) {
assert(pointee_was_visited(pointee), "We should have already visited roots");
@ -131,8 +195,8 @@ if (UseNewCode) printf(PTR_FORMAT ", depth %zu\n", p2i(pointee), depth);
}
mark_pointee_as_visited(pointee);
_reference_stack[depth] = _current_item->r;
if (pointee_was_sampled(pointee)) {
TRC("=> SAMPLE OBJECT FOUND");
add_chain();
}
}
@ -148,7 +212,7 @@ if (UseNewCode) printf(PTR_FORMAT ", depth %zu\n", p2i(pointee), depth);
void DFSClosure::handle_objarrayoop() {
assert(_current_item != nullptr, "Sanity");
ShouldNotReachHere();
const oop pointee = current_pointee();
const size_t depth = current_depth();
assert(depth < _max_depth, "Sanity");
@ -187,10 +251,11 @@ void DFSClosure::handle_objarrayoop() {
const int begidx = chunkindex * array_chunk_size;
const int endidx = MIN2(array_len, (chunkindex + 1) * array_chunk_size);
// push follow-up chunk before pushing the child references, to
// keep doing things depth-first.
// Push follow-up chunk: same reference, same depth, next chunk index.
// Do this before pushing the child references to preserve depth-first
// traversal.
if (endidx < array_len) {
push_to_probe_stack(_current_item->r, chunkindex + 1);
push_to_probe_stack(_current_item->r, pointee, depth, chunkindex + 1);
}
// push child references
@ -201,10 +266,13 @@ void DFSClosure::handle_objarrayoop() {
void DFSClosure::drain_probe_stack() {
DEBUG_ONLY(unsigned last_depth = 0;)
while (!_probe_stack.is_empty() &&
!GranularTimer::is_finished()) {
const ProbeStackItem item = _probe_stack.pop();
assert(item.depth <= (last_depth + 1), "jumping nodes?");
// anchor current item
_current_item = &item;
@ -215,11 +283,12 @@ void DFSClosure::drain_probe_stack() {
//if (current_pointee()->is_objArray()) {
if (false) {
handle_objarrayoop();
printf("handle_objarrayoop\n");
} else {
handle_oop();
}
DEBUG_ONLY(last_depth = item.depth;)
// reset current item
_current_item = nullptr;
@ -234,11 +303,20 @@ void DFSClosure::add_chain() {
Edge* const chain = NEW_RESOURCE_ARRAY(Edge, array_length);
size_t idx = 0;
if (UseNewCode) {
TRC("---- reference stack ----");
for (size_t i = 0; i <= depth; i++) {
const oop pointee = _reference_stack[i].dereference();
TRCOOP("", pointee);
}
TRC("---- reference stack end ----");
}
// aggregate from depth-first search
for (size_t i = 0; i <= depth; i++) {
const size_t next = idx + 1;
const size_t depth = depth - i;
chain[idx++] = Edge(&chain[next], _reference_stack[depth]);
const size_t d = depth - i;
chain[idx++] = Edge(&chain[next], _reference_stack[d]);
}
assert(depth + 1 == idx, "invariant");
assert(array_length == idx + 1, "invariant");
@ -256,23 +334,20 @@ void DFSClosure::do_oop(oop* ref) {
assert(ref != nullptr, "invariant");
assert(is_aligned(ref, HeapWordSize), "invariant");
const oop pointee = HeapAccess<AS_NO_KEEPALIVE>::oop_load(ref);
if (pointee != nullptr) {
push_to_probe_stack(UnifiedOopRef::encode_in_heap(ref), 0);
}
push_to_probe_stack(UnifiedOopRef::encode_in_heap(ref), pointee, current_depth() + 1, 0);
}
void DFSClosure::do_oop(narrowOop* ref) {
assert(ref != nullptr, "invariant");
assert(is_aligned(ref, sizeof(narrowOop)), "invariant");
const oop pointee = HeapAccess<AS_NO_KEEPALIVE>::oop_load(ref);
if (pointee != nullptr) {
push_to_probe_stack(UnifiedOopRef::encode_in_heap(ref), 0);
}
push_to_probe_stack(UnifiedOopRef::encode_in_heap(ref), pointee, current_depth() + 1, 0);
}
void DFSClosure::do_root(UnifiedOopRef ref) {
assert(!ref.is_null(), "invariant");
const oop pointee = ref.dereference();
assert(pointee != nullptr, "invariant");
push_to_probe_stack(ref, 0);
assert(_current_item == nullptr, "invariant");
push_to_probe_stack(ref, pointee, 0, 0);
}

6
src/hotspot/share/jfr/leakprofiler/chains/dfsClosure.hpp
View File

@ -54,7 +54,7 @@ class DFSClosure : public BasicOopIterateClosure {
void add_chain();
struct ProbeStackItem {
struct ProbeStackItem { // 16 bytes
UnifiedOopRef r;
unsigned depth;
int chunkindex; // only used if objArrayOop
@ -63,7 +63,7 @@ class DFSClosure : public BasicOopIterateClosure {
const ProbeStackItem* _current_item;
oop current_pointee() const { return _current_item->r.dereference(); }
size_t current_depth() const { return _current_item->depth; }
size_t current_depth() const { return _current_item == nullptr ? 0 : _current_item->depth; }
bool pointee_was_visited(const oop pointee) const { return _mark_bits->is_marked(pointee); }
void mark_pointee_as_visited(const oop pointee) { _mark_bits->mark_obj(pointee); }
@ -73,7 +73,7 @@ class DFSClosure : public BasicOopIterateClosure {
void handle_oop();
void handle_objarrayoop();
void push_to_probe_stack(UnifiedOopRef ref, int chunkindex);
void push_to_probe_stack(UnifiedOopRef ref, oop pointee, size_t depth, int chunkindex);
public:
virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS_EXCEPT_REFERENT; }

44
src/hotspot/share/jfr/leakprofiler/chains/edgeStore.cpp
View File

@ -29,6 +29,45 @@
#include "oops/oop.inline.hpp"
#include "runtime/safepoint.hpp"
#define TRC(msg) { \
if (UseNewCode) { \
printf(msg); \
printf("\n"); \
fflush(stdout); \
} \
}
#define TRCFMT(format, ...) { \
if (UseNewCode) { \
printf(format, __VA_ARGS__); \
printf("\n"); \
fflush(stdout); \
} \
}
#define TRCOOP(prefix, o) { \
if (UseNewCode) { \
char txt[1024]; \
stringStream ss(txt, sizeof(txt)); \
o->klass()->name()->print_value_on(&ss); \
printf("%s: " PTR_FORMAT " %s ", prefix, p2i(o), txt); \
printf("\n"); \
fflush(stdout); \
} \
}
#define TRCOOPFMT(prefix, o, format, ...) { \
if (UseNewCode) { \
char txt[1024]; \
stringStream ss(txt, sizeof(txt)); \
o->klass()->name()->print_value_on(&ss); \
printf("%s: " PTR_FORMAT " %s ", prefix, p2i(o), txt); \
printf(format, __VA_ARGS__); \
printf("\n"); \
fflush(stdout); \
} \
}
StoredEdge::StoredEdge(const Edge* parent, UnifiedOopRef reference) : Edge(parent, reference), _gc_root_id(0), _skip_length(0) {}
StoredEdge::StoredEdge(const Edge& edge) : Edge(edge), _gc_root_id(0), _skip_length(0) {}
@ -265,6 +304,11 @@ static constexpr const int max_idx = right_n_bits(32 - markWord::lock_bits);
static void store_idx_precondition(oop sample_object, int idx) {
assert(sample_object != nullptr, "invariant");
if (UseNewCode && !sample_object->mark().is_marked()) {
TRCOOP("Sample Object Not Marked", sample_object);
}
assert(sample_object->mark().is_marked(), "invariant");
assert(idx > 0, "invariant");
assert(idx <= max_idx, "invariant");