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From 7fa0e2cc00d64ee0399740ff20971f5c11517172 Mon Sep 17 00:00:00 2001
Date: Fri, 22 Jan 2021 11:36:20 +0800
Subject: Backport of JDK-8186042 for OopmapCache implementation
Summary: Backport of JDK-8186042 for OopmapCache implementation
LLT:
Bug url: https://bugs.openjdk.java.net/browse/JDK-8186042
---
.../shared/vmGCOperations.cpp | 6 +-
.../src/share/vm/interpreter/oopMapCache.cpp | 150 +++++++++++-------
.../src/share/vm/interpreter/oopMapCache.hpp | 11 +-
hotspot/src/share/vm/oops/method.cpp | 26 +--
hotspot/src/share/vm/runtime/memprofiler.cpp | 2 +-
hotspot/src/share/vm/runtime/vframe.cpp | 8 +-
6 files changed, 111 insertions(+), 92 deletions(-)
diff --git a/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.cpp b/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.cpp
index d60f751af..85059b82f 100644
--- a/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.cpp
+++ b/hotspot/src/share/vm/gc_implementation/shared/vmGCOperations.cpp
@@ -40,6 +40,7 @@
#if INCLUDE_ALL_GCS
#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
#endif // INCLUDE_ALL_GCS
+#include "interpreter/oopMapCache.hpp"
#ifndef USDT2
HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
@@ -134,7 +135,10 @@ bool VM_GC_Operation::doit_prologue() {
void VM_GC_Operation::doit_epilogue() {
assert(Thread::current()->is_Java_thread(), "just checking");
- // Release the Heap_lock first.
+ // Clean up old interpreter OopMap entries that were replaced
+ // during the GC thread root traversal.
+ OopMapCache::cleanup_old_entries();
+ // Release the Heap_lock.
SharedHeap* sh = SharedHeap::heap();
if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
Heap_lock->unlock();
diff --git a/hotspot/src/share/vm/interpreter/oopMapCache.cpp b/hotspot/src/share/vm/interpreter/oopMapCache.cpp
index f696bcb25..528906267 100644
--- a/hotspot/src/share/vm/interpreter/oopMapCache.cpp
+++ b/hotspot/src/share/vm/interpreter/oopMapCache.cpp
@@ -30,6 +30,7 @@
#include "prims/jvmtiRedefineClassesTrace.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/signature.hpp"
+#include "runtime/atomic.inline.hpp"
PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
@@ -39,6 +40,9 @@ class OopMapCacheEntry: private InterpreterOopMap {
friend class OopMapCache;
friend class VerifyClosure;
+ private:
+ OopMapCacheEntry* _next;
+
protected:
// Initialization
void fill(methodHandle method, int bci);
@@ -56,8 +60,9 @@ class OopMapCacheEntry: private InterpreterOopMap {
public:
OopMapCacheEntry() : InterpreterOopMap() {
+ _next = NULL;
#ifdef ASSERT
- _resource_allocate_bit_mask = false;
+ _resource_allocate_bit_mask = false;
#endif
}
};
@@ -424,16 +429,6 @@ void OopMapCacheEntry::flush() {
// Implementation of OopMapCache
-#ifndef PRODUCT
-
-static size_t _total_memory_usage = 0;
-
-size_t OopMapCache::memory_usage() {
- return _total_memory_usage;
-}
-
-#endif
-
void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
assert(_resource_allocate_bit_mask,
"Should not resource allocate the _bit_mask");
@@ -474,15 +469,11 @@ inline unsigned int OopMapCache::hash_value_for(methodHandle method, int bci) co
^ ((unsigned int) method->size_of_parameters() << 6);
}
+OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;
-OopMapCache::OopMapCache() :
- _mut(Mutex::leaf, "An OopMapCache lock", true)
-{
- _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry, _size, mtClass);
- // Cannot call flush for initialization, since flush
- // will check if memory should be deallocated
- for(int i = 0; i < _size; i++) _array[i].initialize();
- NOT_PRODUCT(_total_memory_usage += sizeof(OopMapCache) + (sizeof(OopMapCacheEntry) * _size);)
+OopMapCache::OopMapCache() {
+ _array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
+ for(int i = 0; i < _size; i++) _array[i] = NULL;
}
@@ -491,44 +482,59 @@ OopMapCache::~OopMapCache() {
// Deallocate oop maps that are allocated out-of-line
flush();
// Deallocate array
- NOT_PRODUCT(_total_memory_usage -= sizeof(OopMapCache) + (sizeof(OopMapCacheEntry) * _size);)
- FREE_C_HEAP_ARRAY(OopMapCacheEntry, _array, mtClass);
+ FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array, mtClass);
}
OopMapCacheEntry* OopMapCache::entry_at(int i) const {
- return &_array[i % _size];
+ return (OopMapCacheEntry*)OrderAccess::load_ptr_acquire(&(_array[i % _size]));
}
+bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
+ return Atomic::cmpxchg_ptr(entry, &_array[i % _size], old) == old;
+ }
void OopMapCache::flush() {
- for (int i = 0; i < _size; i++) _array[i].flush();
+ for (int i = 0; i < _size; i++) {
+ OopMapCacheEntry* entry = _array[i];
+ if (entry != NULL) {
+ _array[i] = NULL; // no barrier, only called in OopMapCache destructor
+ entry->flush();
+ FREE_C_HEAP_OBJ(entry, mtClass);
+ }
+ }
}
+
void OopMapCache::flush_obsolete_entries() {
- for (int i = 0; i < _size; i++)
- if (!_array[i].is_empty() && _array[i].method()->is_old()) {
+ assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
+ for (int i = 0; i < _size; i++) {
+ OopMapCacheEntry* entry = _array[i];
+ if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {
// Cache entry is occupied by an old redefined method and we don't want
// to pin it down so flush the entry.
+
RC_TRACE(0x08000000, ("flush: %s(%s): cached entry @%d",
- _array[i].method()->name()->as_C_string(),
- _array[i].method()->signature()->as_C_string(), i));
+ entry->method()->name()->as_C_string(),
+ entry->method()->signature()->as_C_string(), i));
- _array[i].flush();
+ _array[i] = NULL;
+ entry->flush();
+ FREE_C_HEAP_OBJ(entry, mtClass);
}
+ }
}
void OopMapCache::lookup(methodHandle method,
int bci,
- InterpreterOopMap* entry_for) const {
- MutexLocker x(&_mut);
-
- OopMapCacheEntry* entry = NULL;
+ InterpreterOopMap* entry_for){
+ assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");
int probe = hash_value_for(method, bci);
+ int i;
+ OopMapCacheEntry* entry = NULL;
// Search hashtable for match
- int i;
for(i = 0; i < _probe_depth; i++) {
entry = entry_at(probe + i);
- if (entry->match(method, bci)) {
+ if (entry != NULL && !entry->is_empty() && entry->match(method, bci)) {
entry_for->resource_copy(entry);
assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
return;
@@ -543,26 +549,31 @@ void OopMapCache::lookup(methodHandle method,
}
// Entry is not in hashtable.
- // Compute entry and return it
+ // Compute entry
+
+ OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
+ tmp->initialize();
+ tmp->fill(method, bci);
+ entry_for->resource_copy(tmp);
if (method->should_not_be_cached()) {
// It is either not safe or not a good idea to cache this Method*
// at this time. We give the caller of lookup() a copy of the
// interesting info via parameter entry_for, but we don't add it to
// the cache. See the gory details in Method*.cpp.
- compute_one_oop_map(method, bci, entry_for);
+ FREE_C_HEAP_OBJ(tmp, mtClass);
return;
}
// First search for an empty slot
for(i = 0; i < _probe_depth; i++) {
- entry = entry_at(probe + i);
- if (entry->is_empty()) {
- entry->fill(method, bci);
- entry_for->resource_copy(entry);
- assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
- return;
- }
+ entry = entry_at(probe + i);
+ if (entry == NULL) {
+ if(put_at(probe + i, tmp, NULL)) {
+ assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
+ return;
+ }
+ }
}
if (TraceOopMapGeneration) {
@@ -571,30 +582,51 @@ void OopMapCache::lookup(methodHandle method,
}
// No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
- //entry_at(probe + _probe_depth - 1)->flush();
- //for(i = _probe_depth - 1; i > 0; i--) {
- // // Coping entry[i] = entry[i-1];
- // OopMapCacheEntry *to = entry_at(probe + i);
- // OopMapCacheEntry *from = entry_at(probe + i - 1);
- // to->copy(from);
- // }
+ // where the first entry in the collision array is replaced with the new one.
+ OopMapCacheEntry* old = entry_at(probe + 0);
+ if (put_at(probe + 0, tmp, old)) {
+ enqueue_for_cleanup(old);
+ } else {
+ enqueue_for_cleanup(tmp);
+ }
- assert(method->is_method(), "gaga");
+ assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
- entry = entry_at(probe + 0);
- entry->fill(method, bci);
+ return;
+}
- // Copy the newly cached entry to input parameter
- entry_for->resource_copy(entry);
+void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
+ bool success = false;
+ OopMapCacheEntry* head;
+ do {
+ head = _old_entries;
+ entry->_next = head;
+ success = Atomic::cmpxchg_ptr((intptr_t*)entry, (intptr_t*)&_old_entries, (intptr_t*)head) == (intptr_t*)head;
+ } while (!success);
if (TraceOopMapGeneration) {
ResourceMark rm;
- tty->print("Done with ");
- method->print_value(); tty->cr();
+ tty->print_cr("enqueue %s at bci %d for cleanup",
+ entry->method()->name_and_sig_as_C_string(), entry->bci());
}
- assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
+}
- return;
+// This is called after GC threads are done and nothing is accessing the old_entries
+// list, so no synchronization needed.
+void OopMapCache::cleanup_old_entries() {
+ OopMapCacheEntry* entry = _old_entries;
+ _old_entries = NULL;
+ while (entry != NULL) {
+ if (TraceOopMapGeneration) {
+ ResourceMark rm;
+ tty->print_cr("cleanup entry %s at bci %d",
+ entry->method()->name_and_sig_as_C_string(), entry->bci());
+ }
+ OopMapCacheEntry* next = entry->_next;
+ entry->flush();
+ FREE_C_HEAP_OBJ(entry, mtClass);
+ entry = next;
+ }
}
void OopMapCache::compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry) {
diff --git a/hotspot/src/share/vm/interpreter/oopMapCache.hpp b/hotspot/src/share/vm/interpreter/oopMapCache.hpp
index 99fbe8168..ecbe4340a 100644
--- a/hotspot/src/share/vm/interpreter/oopMapCache.hpp
+++ b/hotspot/src/share/vm/interpreter/oopMapCache.hpp
@@ -147,17 +147,19 @@ class InterpreterOopMap: ResourceObj {
};
class OopMapCache : public CHeapObj<mtClass> {
+ static OopMapCacheEntry* volatile _old_entries;
private:
enum { _size = 32, // Use fixed size for now
_probe_depth = 3 // probe depth in case of collisions
};
- OopMapCacheEntry* _array;
+ OopMapCacheEntry* volatile * _array;
unsigned int hash_value_for(methodHandle method, int bci) const;
OopMapCacheEntry* entry_at(int i) const;
- mutable Mutex _mut;
+ bool put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old);
+ static void enqueue_for_cleanup(OopMapCacheEntry* entry);
void flush();
@@ -170,13 +172,12 @@ class OopMapCache : public CHeapObj<mtClass> {
// Returns the oopMap for (method, bci) in parameter "entry".
// Returns false if an oop map was not found.
- void lookup(methodHandle method, int bci, InterpreterOopMap* entry) const;
+ void lookup(methodHandle method, int bci, InterpreterOopMap* entry);
// Compute an oop map without updating the cache or grabbing any locks (for debugging)
static void compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry);
- // Returns total no. of bytes allocated as part of OopMapCache's
- static size_t memory_usage() PRODUCT_RETURN0;
+ static void cleanup_old_entries();
};
#endif // SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP
diff --git a/hotspot/src/share/vm/oops/method.cpp b/hotspot/src/share/vm/oops/method.cpp
index 9e58c0126..24fae4d30 100644
--- a/hotspot/src/share/vm/oops/method.cpp
+++ b/hotspot/src/share/vm/oops/method.cpp
@@ -216,26 +216,14 @@ int Method::fast_exception_handler_bci_for(methodHandle mh, KlassHandle ex_klass
}
void Method::mask_for(int bci, InterpreterOopMap* mask) {
-
- Thread* myThread = Thread::current();
- methodHandle h_this(myThread, this);
-#ifdef ASSERT
- bool has_capability = myThread->is_VM_thread() ||
- myThread->is_ConcurrentGC_thread() ||
- myThread->is_GC_task_thread();
-
- if (!has_capability) {
- if (!VerifyStack && !VerifyLastFrame) {
- // verify stack calls this outside VM thread
- warning("oopmap should only be accessed by the "
- "VM, GC task or CMS threads (or during debugging)");
- InterpreterOopMap local_mask;
- method_holder()->mask_for(h_this, bci, &local_mask);
- local_mask.print();
- }
+ methodHandle h_this(Thread::current(), this);
+ // Only GC uses the OopMapCache during thread stack root scanning
+ // any other uses generate an oopmap but do not save it in the cache.
+ if (Universe::heap()->is_gc_active()) {
+ method_holder()->mask_for(h_this, bci, mask);
+ } else {
+ OopMapCache::compute_one_oop_map(h_this, bci, mask);
}
-#endif
- method_holder()->mask_for(h_this, bci, mask);
return;
}
diff --git a/hotspot/src/share/vm/runtime/memprofiler.cpp b/hotspot/src/share/vm/runtime/memprofiler.cpp
index c1cfb60bd..ddb22601f 100644
--- a/hotspot/src/share/vm/runtime/memprofiler.cpp
+++ b/hotspot/src/share/vm/runtime/memprofiler.cpp
@@ -129,7 +129,7 @@ void MemProfiler::do_trace() {
fprintf(_log_fp, UINTX_FORMAT_W(6) "," UINTX_FORMAT_W(6) "," UINTX_FORMAT_W(6) "\n",
handles_memory_usage / K,
resource_memory_usage / K,
- OopMapCache::memory_usage() / K);
+ 0L);
fflush(_log_fp);
}
diff --git a/hotspot/src/share/vm/runtime/vframe.cpp b/hotspot/src/share/vm/runtime/vframe.cpp
index 0d5524118..b3a6d0770 100644
--- a/hotspot/src/share/vm/runtime/vframe.cpp
+++ b/hotspot/src/share/vm/runtime/vframe.cpp
@@ -365,13 +365,7 @@ StackValueCollection* interpretedVFrame::expressions() const {
StackValueCollection* interpretedVFrame::stack_data(bool expressions) const {
InterpreterOopMap oop_mask;
- // oopmap for current bci
- if (TraceDeoptimization && Verbose) {
- methodHandle m_h(Thread::current(), method());
- OopMapCache::compute_one_oop_map(m_h, bci(), &oop_mask);
- } else {
- method()->mask_for(bci(), &oop_mask);
- }
+ method()->mask_for(bci(), &oop_mask);
const int mask_len = oop_mask.number_of_entries();
--
2.19.0
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