Make sure the temporary frames array is freed

DataDog · Apr 9, 2024 · c7a9781 · c7a9781
1 parent 88819f6
commit c7a9781
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Showing 2 changed files with 9 additions and 9 deletions.
diff --git a/ddprof-lib/src/main/cpp/livenessTracker.cpp b/ddprof-lib/src/main/cpp/livenessTracker.cpp
@@ -51,18 +51,21 @@ void LivenessTracker::cleanup_table(bool forced) {
     u32 sz, newsz = 0;
     std::set<jclass> kept_classes;
     for (u32 i = 0; i < (sz = _table_size); i++) {
-        if (_table[i].ref != NULL && !env->IsSameObject(_table[i].ref, NULL)) {
+        if (_table[i].ref != nullptr && !env->IsSameObject(_table[i].ref, nullptr)) {
             // it survived one more GarbageCollectionFinish event
             u32 target = newsz++;
             if (target != i) {
                 _table[target] = _table[i];
-                _table[i].ref = NULL;
+                _table[i].ref = nullptr;
+                assert(_table[i].frames == _table[target].frames);
+                _table[i].frames = nullptr;
             }
             _table[target].age += epoch_diff;
         } else {
             env->DeleteWeakGlobalRef(_table[i].ref);
-            _table[i].ref = NULL;
+            _table[i].ref = nullptr;
             delete[] _table[i].frames;
+            _table[i].frames = nullptr;
         }
     }
 
@@ -296,8 +299,6 @@ void LivenessTracker::track(JNIEnv* env, AllocEvent &event, jint tid, jobject ob
             }
         }
     }
-
-    delete[] frames;
 }
 
 void JNICALL LivenessTracker::GarbageCollectionFinish(jvmtiEnv *jvmti_env) {

diff --git a/ddprof-lib/src/main/cpp/objectSampler.cpp b/ddprof-lib/src/main/cpp/objectSampler.cpp
@@ -106,12 +106,11 @@ void ObjectSampler::recordAllocation(jvmtiEnv* jvmti, JNIEnv* jni, jthread threa
     }
 
     if (_record_liveness) {
-        // 'frames' will be released by the tracker
         LivenessTracker::instance()->track(jni, event, tid, object, frames_size, frames);
-    } else {
-        // otherwise the 'frames' need to be deleted here
-        delete[] frames;
     }
+
+    // it's safe to delete frames - the liveness tracker keeps a full copy of the frames and manages its own memory
+    delete[] frames;
 }
 
 Error ObjectSampler::check(Arguments& args) {