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[PROF-12714] Add CriticalNative support #282

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[PROF-12714] Add CriticalNative support #282

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4feff30
[PROF-12714] Add CriticalNative support
zhengyu123 Oct 10, 2025
6cfd40f
Disable CriticalJNINatives on aarch64
zhengyu123 Oct 24, 2025
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104 changes: 81 additions & 23 deletions ddprof-lib/src/main/cpp/javaApi.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,11 @@ Java_com_datadoghq_profiler_JavaProfiler_init0(JNIEnv *env, jclass unused) {
return VM::initProfilerBridge(nullptr, true);
}

extern "C" JNIEXPORT jboolean JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_init0() {
return VM::initProfilerBridge(nullptr, true);
}

Comment on lines +71 to +75
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I'm curious, why have a JavaCritical variant for ìnit0`? This one doesn't look like it would ever be on the critical path so I don't see when the JVM would pick this one? 👀

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_stop0(JNIEnv *env, jobject unused) {
Error error = Profiler::instance()->stop();
Expand All @@ -78,10 +83,16 @@ Java_com_datadoghq_profiler_JavaProfiler_stop0(JNIEnv *env, jobject unused) {
}

extern "C" DLLEXPORT jint JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getTid0(JNIEnv *env, jobject unused) {
Java_com_datadoghq_profiler_JavaProfiler_getTid0(JNIEnv *env, jclass unused) {
return OS::threadId();
}

extern "C" DLLEXPORT jint JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_getTid0() {
return OS::threadId();
}


extern "C" DLLEXPORT jstring JNICALL
Java_com_datadoghq_profiler_JavaProfiler_execute0(JNIEnv *env, jobject unused,
jstring command) {
Expand Down Expand Up @@ -113,22 +124,26 @@ Java_com_datadoghq_profiler_JavaProfiler_execute0(JNIEnv *env, jobject unused,

extern "C" DLLEXPORT jstring JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getStatus0(JNIEnv* env,
jobject unused) {
jclass unused) {
char msg[2048];
int ret = Profiler::instance()->status((char*)msg, sizeof(msg) - 1);
return env->NewStringUTF(msg);
}

extern "C" DLLEXPORT jlong JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getSamples(JNIEnv *env,
jobject unused) {
jclass unused) {
return (jlong)Profiler::instance()->total_samples();
}

extern "C" DLLEXPORT jlong JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_getSamples() {
return (jlong)Profiler::instance()->total_samples();
}
Comment on lines 133 to 142
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Similar note to init0 -- I only see getSamples being used for the MX bean so... not particularly perf-sensitive?


// some duplication between add and remove, though we want to avoid having an extra branch in the hot path
extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_filterThreadAdd0(JNIEnv *env,
jobject unused) {
JavaCritical_com_datadoghq_profiler_JavaProfiler_filterThreadAdd0() {
ProfiledThread *current = ProfiledThread::current();
if (unlikely(current == nullptr)) {
assert(false);
Expand Down Expand Up @@ -158,8 +173,13 @@ Java_com_datadoghq_profiler_JavaProfiler_filterThreadAdd0(JNIEnv *env,
}

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_filterThreadRemove0(JNIEnv *env,
jobject unused) {
Java_com_datadoghq_profiler_JavaProfiler_filterThreadAdd0(JNIEnv *env,
jclass unused) {
JavaCritical_com_datadoghq_profiler_JavaProfiler_filterThreadAdd0();
}
Comment on lines 175 to +179
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I'm curious -- do you know if this will add an extra indirection when calling this function? Or will the compiler inline/alias this call?


extern "C" DLLEXPORT void JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_filterThreadRemove0() {
ProfiledThread *current = ProfiledThread::current();
if (unlikely(current == nullptr)) {
assert(false);
Expand All @@ -182,11 +202,15 @@ Java_com_datadoghq_profiler_JavaProfiler_filterThreadRemove0(JNIEnv *env,
thread_filter->remove(slot_id);
}

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_filterThreadRemove0(JNIEnv *env,
jclass unused) {
JavaCritical_com_datadoghq_profiler_JavaProfiler_filterThreadRemove0();
}

// Backward compatibility for existing code
extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_filterThread0(JNIEnv *env,
jobject unused,
jboolean enable) {
JavaCritical_com_datadoghq_profiler_JavaProfiler_filterThread0(jboolean enable) {
ProfiledThread *current = ProfiledThread::current();
Comment on lines 211 to 214
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Wait, is this correct at all? I know this hasn't changed in this PR, but looking at AsyncProfiler::filterThread:

    private void filterThread(Thread thread, boolean enable) {
        if (thread == null || thread == Thread.currentThread()) {
            filterThread0(null, enable);
        } else {
            // Need to take lock to avoid race condition with a thread state change
            synchronized (thread) {
                Thread.State state = thread.getState();
                if (state != Thread.State.NEW && state != Thread.State.TERMINATED) {
                    filterThread0(thread, enable);
                }
            }
        }
    }

...that else branch seems to be completely broken?

(I looked a bit at java-profiler and dd-trace-java and it doesn't look like this code is still in-use... Perhaps easier to just remove it?)

if (unlikely(current == nullptr)) {
assert(false);
Expand Down Expand Up @@ -225,9 +249,16 @@ Java_com_datadoghq_profiler_JavaProfiler_filterThread0(JNIEnv *env,
}
}

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_filterThread0(JNIEnv *env,
jclass unused,
jboolean enable) {
JavaCritical_com_datadoghq_profiler_JavaProfiler_filterThread0(enable);
}

extern "C" DLLEXPORT jobject JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getContextPage0(JNIEnv *env,
jobject unused,
jclass unused,
jint tid) {
ContextPage page = Contexts::getPage((int)tid);
if (page.storage == 0) {
Expand All @@ -238,21 +269,32 @@ Java_com_datadoghq_profiler_JavaProfiler_getContextPage0(JNIEnv *env,

extern "C" DLLEXPORT jlong JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getContextPageOffset0(JNIEnv *env,
jobject unused,
jclass unused,
jint tid) {
ContextPage page = Contexts::getPage((int)tid);
return (jlong)page.storage;
}

extern "C" DLLEXPORT jlong JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_getContextPageOffset0(jint tid) {
ContextPage page = Contexts::getPage((int)tid);
return (jlong)page.storage;
}

extern "C" DLLEXPORT jint JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getMaxContextPages0(JNIEnv *env,
jobject unused) {
jclass unused) {
return (jint)Contexts::getMaxPages();
}

extern "C" DLLEXPORT jint JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_getMaxContextPages0() {
Comment on lines 284 to +291
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Similar note to init0 -- this doesn't look very performance-sensitive?

return (jint)Contexts::getMaxPages();
}

extern "C" DLLEXPORT jboolean JNICALL
Java_com_datadoghq_profiler_JavaProfiler_recordTrace0(
JNIEnv *env, jobject unused, jlong rootSpanId, jstring endpoint,
JNIEnv *env, jclass unused, jlong rootSpanId, jstring endpoint,
jstring operation, jint sizeLimit) {
JniString endpoint_str(env, endpoint);
u32 endpointLabel = Profiler::instance()->stringLabelMap()->bounded_lookup(
Expand All @@ -274,7 +316,7 @@ Java_com_datadoghq_profiler_JavaProfiler_recordTrace0(

extern "C" DLLEXPORT jint JNICALL
Java_com_datadoghq_profiler_JavaProfiler_registerConstant0(JNIEnv *env,
jobject unused,
jclass unused,
jstring value) {
JniString value_str(env, value);
u32 encoding = Profiler::instance()->contextValueMap()->bounded_lookup(
Expand All @@ -283,15 +325,15 @@ Java_com_datadoghq_profiler_JavaProfiler_registerConstant0(JNIEnv *env,
}

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_dump0(JNIEnv *env, jobject unused,
Java_com_datadoghq_profiler_JavaProfiler_dump0(JNIEnv *env, jclass unused,
jstring path) {
JniString path_str(env, path);
Profiler::instance()->dump(path_str.c_str(), path_str.length());
}

extern "C" DLLEXPORT jobject JNICALL
Java_com_datadoghq_profiler_JavaProfiler_getDebugCounters0(JNIEnv *env,
jobject unused) {
jclass unused) {
#ifdef COUNTERS
return env->NewDirectByteBuffer((void *)Counters::getCounters(),
(jlong)Counters::size());
Expand All @@ -302,7 +344,7 @@ Java_com_datadoghq_profiler_JavaProfiler_getDebugCounters0(JNIEnv *env,

extern "C" DLLEXPORT jobjectArray JNICALL
Java_com_datadoghq_profiler_JavaProfiler_describeDebugCounters0(
JNIEnv *env, jobject unused) {
JNIEnv *env, jclass unused) {
#ifdef COUNTERS
std::vector<const char *> counter_names = Counters::describeCounters();
jobjectArray array = (jobjectArray)env->NewObjectArray(
Expand All @@ -320,7 +362,7 @@ Java_com_datadoghq_profiler_JavaProfiler_describeDebugCounters0(

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_recordSettingEvent0(
JNIEnv *env, jobject unused, jstring name, jstring value, jstring unit) {
JNIEnv *env, jclass unused, jstring name, jstring value, jstring unit) {
int tid = ProfiledThread::currentTid();
if (tid < 0) {
return;
Expand All @@ -343,7 +385,7 @@ static int dictionarizeClassName(JNIEnv* env, jstring className) {

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_recordQueueEnd0(
JNIEnv *env, jobject unused, jlong startTime, jlong endTime, jstring task,
JNIEnv *env, jclass unused, jlong startTime, jlong endTime, jstring task,
jstring scheduler, jthread origin, jstring queueType, jint queueLength) {
int tid = ProfiledThread::currentTid();
if (tid < 0) {
Expand Down Expand Up @@ -379,23 +421,39 @@ Java_com_datadoghq_profiler_JavaProfiler_recordQueueEnd0(

extern "C" DLLEXPORT jlong JNICALL
Java_com_datadoghq_profiler_JavaProfiler_currentTicks0(JNIEnv *env,
jobject unused) {
jclass unused) {
return TSC::ticks();
}

extern "C" DLLEXPORT jlong JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_currentTicks0() {
return TSC::ticks();
}

extern "C" DLLEXPORT jlong JNICALL
Java_com_datadoghq_profiler_JavaProfiler_tscFrequency0(JNIEnv *env,
jobject unused) {
jclass unused) {
return TSC::frequency();
}

extern "C" DLLEXPORT jlong JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_tscFrequency0() {
Comment on lines 433 to +440
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Similar note to init0 -- this value seems to be saved in a static final on the Java side and never called again.

return TSC::frequency();
}

extern "C" DLLEXPORT void JNICALL
Java_com_datadoghq_profiler_JavaProfiler_mallocArenaMax0(JNIEnv *env,
jobject unused,
jclass unused,
jint maxArenas) {
ddprof::OS::mallocArenaMax(maxArenas);
}

extern "C" DLLEXPORT void JNICALL
JavaCritical_com_datadoghq_profiler_JavaProfiler_mallocArenaMax0(jint maxArenas) {
ddprof::OS::mallocArenaMax(maxArenas);
}


Comment on lines 444 to +456
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Similar note to init0 and others above.

extern "C" DLLEXPORT jstring JNICALL
Java_com_datadoghq_profiler_JVMAccess_findStringJVMFlag0(JNIEnv *env,
jobject unused,
Expand Down
11 changes: 11 additions & 0 deletions ddprof-lib/src/main/cpp/vmStructs_dd.cpp
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Expand Up @@ -44,6 +44,7 @@ namespace ddprof {
initOffsets();
initJvmFunctions();
initUnsafeFunctions();
initCriticalJNINatives();
}

void VMStructs_::initOffsets() {
Expand Down Expand Up @@ -98,6 +99,16 @@ namespace ddprof {
}
}

void VMStructs_::initCriticalJNINatives() {
#ifdef __aarch64__
// aarch64 does not support CriticalJNINatives
JVMFlag* flag = JVMFlag::find("CriticalJNINatives", {JVMFlag::Type::Bool});
if (flag != nullptr && flag->get()) {
flag->set(0);
}
#endif // __aarch64__
}
Comment on lines +102 to +110
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I'm curious -- why is this needed? E.g. if the feature isn't supported, what does disabling it do?


const void *VMStructs_::findHeapUsageFunc() {
if (VM::hotspot_version() < 17) {
// For JDK 11 it is really unreliable to find the memory_usage function -
Expand Down
1 change: 1 addition & 0 deletions ddprof-lib/src/main/cpp/vmStructs_dd.h
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Expand Up @@ -52,6 +52,7 @@ namespace ddprof {
static void initOffsets();
static void initJvmFunctions();
static void initUnsafeFunctions();
static void initCriticalJNINatives();

static void checkNativeBinding(jvmtiEnv *jvmti, JNIEnv *jni, jmethodID method,
void *address);
Expand Down
8 changes: 4 additions & 4 deletions ddprof-lib/src/main/java/com/datadoghq/profiler/JavaProfiler.java
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Expand Up @@ -154,7 +154,7 @@ public void stop() throws IllegalStateException {
*
* @return Number of samples
*/
public native long getSamples();
public static native long getSamples();

/**
* Get profiler agent version, e.g. "1.0"
Expand Down Expand Up @@ -470,10 +470,10 @@ public Map<String, Long> getDebugCounters() {
private native void stop0() throws IllegalStateException;
private native String execute0(String command) throws IllegalArgumentException, IllegalStateException, IOException;

private native void filterThreadAdd0();
private native void filterThreadRemove0();
private static native void filterThreadAdd0();
private static native void filterThreadRemove0();
// Backward compatibility for existing code
private native void filterThread0(boolean enable);
private static native void filterThread0(boolean enable);

private static native int getTid0();
private static native ByteBuffer getContextPage0(int tid);
Expand Down
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