Fix JNI wrapper memory leak

src/Runtime/jni/jnidummy.c

@@ -14,12 +14,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "com_ibm_onnxmlir_OMModel.h"
+#include "com_ibm_onnxmlir_OMTensor.h"
 
 /* Dummy routine to force the link editor to embed code in libjniruntime.a
    into libmodel.so */
 void __dummy_do_not_call__(JNIEnv *env, jclass cls, jobject obj) {
   Java_com_ibm_onnxmlir_OMModel_main_1graph_1jni(NULL, NULL, NULL);
-  Java_com_ibm_onnxmlir_OMModel_query_1entry_1points(NULL, NULL);
+  Java_com_ibm_onnxmlir_OMModel_query_1entry_1points_1jni(NULL, NULL);
   Java_com_ibm_onnxmlir_OMModel_input_1signature_1jni(NULL, NULL, NULL);
   Java_com_ibm_onnxmlir_OMModel_output_1signature_1jni(NULL, NULL, NULL);
+  Java_com_ibm_onnxmlir_OMTensor_free_1data_1jni(NULL, NULL, NULL);
 }

src/Runtime/jni/jniwrapper.c

@@ -175,7 +175,7 @@ const char *jnistr[] = {
     "com/ibm/onnxmlir/OMTensor",       /* 3  CLS_COM_IBM_ONNXMLIR_OMTENSOR    */
     "com/ibm/onnxmlir/OMTensorList",   /* 4  CLS_COM_IBM_ONNXMLIR_OMTENSORLIST*/
     "<init>",                          /* 5  CTOR_INIT                        */
-    "(Ljava/nio/ByteBuffer;[J[JI)V",   /* 6  CTOR_OMTENSOR                    */
+    "(Ljava/nio/ByteBuffer;[J[JIZ)V",  /* 6  CTOR_OMTENSOR                    */
     "([Lcom/ibm/onnxmlir/OMTensor;)V", /* 7  CTOR_OMTENSORLIST */
     "()Ljava/nio/ByteBuffer;",         /* 8  SIG_GET_DATA                     */
     "(Ljava/nio/ByteBuffer;)V",        /* 9  SIG_SET_DATA                     */
@@ -598,9 +598,11 @@ jobject omtl_native_to_java(
      * If jni_owning is true, we take ownership by setting owner flag
      * to false. This means that when we call omTensorListDestroy
      * the data buffer will not be freed since it has been given to
-     * the Java direct byte buffer and the Java GC will be responsible
-     * for freeing the data buffer. This way we avoid copying the data
-     * buffer.
+     * the Java direct byte buffer. However, the direct byte buffer
+     * created by NewDirectByteBuffer is not subject to Java GC so we
+     * pass clean=true to the OMTensor construct to initializ a cleaner
+     * to manually free the data buffer. This way we avoid copying the
+     * data buffer.
      *
      * If jni_owning is false, it means the data buffer is not freeable
      * due to one of the two following cases:
@@ -609,23 +611,18 @@ jobject omtl_native_to_java(
      *     responsible for freeing it
      *   - the data buffer is static
      *
-     * Either way, since the data buffer will be given to Java and is
-     * subject to GC, we must make a copy of the data buffer.
+     * Either way, since the data buffer given to Java is not subject
+     * to GC, we can simply pass it through with clean=false and no
+     * cleaner will be initialized.
      */
     void *jbytebuffer_data = jni_data;
     if (jni_owning) {
       LIB_CALL(omTensorSetOwning(jni_omts[i], (int64_t)0), 1, env,
           japi->jecpt_cls, "");
       LOG_PRINTF(LOG_DEBUG, "omt[%d]:%p data %p ownership taken", i,
           jni_omts[i], jni_data);
-    } else {
-      LIB_VAR_CALL(jbytebuffer_data, malloc(jni_bufferSize),
-          jbytebuffer_data != NULL, env, japi->jecpt_cls, "jbytebuffer_data=%p",
-          jbytebuffer_data);
-      memcpy(jbytebuffer_data, jni_data, jni_bufferSize);
-      LOG_PRINTF(LOG_DEBUG, "omt[%d]:%p data %p copied into %p", i, jni_omts[i],
-          jni_data, jbytebuffer_data);
     }
+
     JNI_TYPE_VAR_CALL(env, jobject, jomt_data,
         (*env)->NewDirectByteBuffer(env, jbytebuffer_data, jomt_bufferSize),
         jomt_data != NULL, japi->jecpt_cls, "omt[%d]:jomt_data=%p", i,
@@ -652,7 +649,8 @@ jobject omtl_native_to_java(
     /* Create the OMTensor Java object */
     JNI_TYPE_VAR_CALL(env, jobject, jobj_omt,
         (*env)->NewObject(env, japi->jomt_cls, japi->jomt_constructor,
-            jomt_data, jomt_shape, jomt_strides, jomt_dataType),
+            jomt_data, jomt_shape, jomt_strides, jomt_dataType,
+            (jboolean)jni_owning),
         jobj_omt != NULL, japi->jecpt_cls, "omt[%d]:jobj_omt=%p", i, jobj_omt);
 
     /* Set the OMTensor object in the object array */
@@ -732,7 +730,8 @@ static inline char *conv(const char *str, size_t (*fptr)(char *)) {
 #endif
 
 JNIEXPORT jobjectArray JNICALL
-Java_com_ibm_onnxmlir_OMModel_query_1entry_1points(JNIEnv *env, jclass cls) {
+Java_com_ibm_onnxmlir_OMModel_query_1entry_1points_1jni(
+    JNIEnv *env, jclass cls) {
 
   log_init();
 
@@ -910,3 +909,23 @@ JNIEXPORT jstring JNICALL Java_com_ibm_onnxmlir_OMModel_output_1signature_1jni(
 
   return java_osig;
 }
+
+JNIEXPORT jobject JNICALL Java_com_ibm_onnxmlir_OMTensor_free_1data_1jni(
+    JNIEnv *env, jclass cls, jobject java_data) {
+
+  log_init();
+
+  /* Find and initialize Java Exception class */
+  JNI_TYPE_VAR_CALL(env, jclass, jecpt_cls,
+      (*env)->FindClass(env, jnistr[CLS_JAVA_LANG_EXCEPTION]),
+      jecpt_cls != NULL, NULL, "Class java/lang/Exception not found");
+
+  /* Get native data buffer backing direct byte buffer */
+  JNI_TYPE_VAR_CALL(env, void *, jni_data,
+      (*env)->GetDirectBufferAddress(env, java_data), jni_data != NULL,
+      jecpt_cls, "jni_data=%p", jni_data);
+
+  free(jni_data);
+
+  return NULL;
+}

src/Runtime/jni/src/com/ibm/onnxmlir/OMModel.java

@@ -168,7 +168,7 @@ public class OMModel {
     }
 
     private static native OMTensorList main_graph_jni(OMTensorList list);
-    private static native String[] query_entry_points();
+    private static native String[] query_entry_points_jni();
     private static native String input_signature_jni(String entry_point);
     private static native String output_signature_jni(String entry_point);
 
@@ -188,7 +188,7 @@ public static OMTensorList mainGraph(OMTensorList list) {
      * @return String array of entry point names
      */
     public static String[] queryEntryPoints() {
-	return query_entry_points();
+	return query_entry_points_jni();
     }
 
     /**

src/Runtime/jni/src/com/ibm/onnxmlir/OMTensor.java

@@ -2,6 +2,7 @@
 
 package com.ibm.onnxmlir;
 
+import java.lang.ref.Cleaner;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.DoubleBuffer;
@@ -15,7 +16,7 @@
  * shape, strides, data type, etc. associated with a tensor
  * input/output.
  */
-public class OMTensor {
+public class OMTensor implements AutoCloseable {
 
     /* We can use enum but that creates another class
      * which complicates things for JNI.
@@ -92,6 +93,43 @@ public class OMTensor {
      */
     private int _rank;
 
+    /* ByteBuffer created by jniwrapper using NewDirectByteBuffer
+     * apparently doesn't get GC-ed. So we need to register a
+     * cleaner to manually free the output tensor data buffer
+     * created by the model runtime.
+     *
+     * Note the cleaner API requires Java 9+. For Java 8, we can
+     * use finalize() but be aware that it has been deprecated since
+     * Java 9 (hence the use of cleaner).
+     *
+     * _cleanable is registered by the internal JNI-wrapper-only
+     * OMTensor constructor to signal the need for manual freeing.
+     */
+    private static native Void free_data_jni(ByteBuffer data);
+
+    /* Create a Cleaner object and use it to register our freeData
+     * routine.
+     */
+    private static final Cleaner _cleaner = Cleaner.create();
+    private final Cleaner.Cleanable _cleanable;
+
+    /* When OMTensor becomes phantom reachable, JVM will call the
+     * cleaner we registered and run freeData. We call the native
+     * free_data_jni to do the manual freeing.
+     */
+    private static Runnable freeData(ByteBuffer data) {
+	return() -> {
+	    free_data_jni(data);
+	};
+    }
+
+    /* User can explicit call close to run freeData. This is required
+     * for implementing AutoCloseable. */
+    @Override
+    public void close() {
+	if (_cleanable != null) _cleanable.clean();
+    }
+
     /**
      * Constructor
      *
@@ -107,6 +145,7 @@ public OMTensor(byte[] data, long[] shape, boolean flag) {
 	else
 	    setByteData(data);
 	putShape(shape);
+	_cleanable = null;
     }
 
     /**
@@ -132,6 +171,7 @@ public OMTensor(byte[] data, long[] shape) {
     public OMTensor(short[] data, long[] shape) {
         setShortData(data);
         putShape(shape);
+	_cleanable = null;
     }
 
     /**
@@ -145,6 +185,7 @@ public OMTensor(short[] data, long[] shape) {
     public OMTensor(int[] data, long[] shape) {
         setIntData(data);
         putShape(shape);
+	_cleanable = null;
     }
 
     /**
@@ -158,6 +199,7 @@ public OMTensor(int[] data, long[] shape) {
     public OMTensor(long[] data, long[] shape) {
         setLongData(data);
         putShape(shape);
+	_cleanable = null;
     }
 
     /**
@@ -171,6 +213,7 @@ public OMTensor(long[] data, long[] shape) {
     public OMTensor(float[] data, long[] shape) {
         setFloatData(data);
         putShape(shape);
+	_cleanable = null;
     }
 
     /**
@@ -184,6 +227,7 @@ public OMTensor(float[] data, long[] shape) {
     public OMTensor(double[] data, long[] shape) {
         setDoubleData(data);
         putShape(shape);
+	_cleanable = null;
     }
 
 
@@ -588,6 +632,7 @@ protected OMTensor(ByteBuffer data, long[] shape, ByteOrder endian, int dataType
         _data = data.order(endian);
         _dataType = dataType;
 	putShape(shape);
+	_cleanable = null;
     }
 
     /**
@@ -598,7 +643,7 @@ protected OMTensor(ByteBuffer data, long[] shape, ByteOrder endian, int dataType
      * @param strides data stride
      * @param dataType data type
      */
-    protected OMTensor(ByteBuffer data, long[] shape, long[] strides, int dataType) {
+    protected OMTensor(ByteBuffer data, long[] shape, long[] strides, int dataType, boolean clean) {
         if (shape.length != strides.length)
             throw new IllegalArgumentException(
                     "shape.length (" + shape.length + ") != stride.length (" + strides.length + ")");
@@ -610,6 +655,7 @@ protected OMTensor(ByteBuffer data, long[] shape, long[] strides, int dataType)
         _rank = shape.length;
         _shape = shape;
         _strides = strides;
+	_cleanable = clean ? _cleaner.register(this, freeData(_data)) : null;
     }
 
     /**

test/backend/inference_backend.py

@@ -1181,7 +1181,8 @@ def JniExecutionSession(jar_name, inputs):
     )
 
     dtype = {
-        "b1": np.bool,
+        # np.bool is deprecated, use np.bool_ instead
+        "b1": np.bool_,
         "i1": np.int8,
         "u1": np.uint8,
         "i2": np.int16,