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POByteBuffer not releasing memory
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copied!<p>On Android, a direct ByteBuffer does not ever seem to release its memory, not even when calling System.gc(). </p> <p>Example: doing</p> <pre><code>Log.v("?", Long.toString(Debug.getNativeHeapAllocatedSize())); ByteBuffer buffer = allocateDirect(LARGE_NUMBER); buffer=null; System.gc(); Log.v("?", Long.toString(Debug.getNativeHeapAllocatedSize())); </code></pre> <p>gives two numbers in the log, the second one being at least LARGE_NUMBER larger than the first.</p> <p>How do I get rid of this leak?</p> <hr> <p><strong>Added:</strong></p> <p>Following the suggestion by Gregory to handle alloc/free on the C++ side, I then defined</p> <pre><code>JNIEXPORT jobject JNICALL Java_com_foo_bar_allocNative(JNIEnv* env, jlong size) { void* buffer = malloc(size); jobject directBuffer = env->NewDirectByteBuffer(buffer, size); jobject globalRef = env->NewGlobalRef(directBuffer); return globalRef; } JNIEXPORT void JNICALL Java_com_foo_bar_freeNative(JNIEnv* env, jobject globalRef) { void *buffer = env->GetDirectBufferAddress(globalRef); free(buffer); env->DeleteGlobalRef(globalRef); } </code></pre> <p>I then get my ByteBuffer on the JAVA side with</p> <pre><code>ByteBuffer myBuf = allocNative(LARGE_NUMBER); </code></pre> <p>and free it with</p> <pre><code>freeNative(myBuf); </code></pre> <p>Unfortunately, while it does allocate fine, it a) still keeps the memory allocated according to <code>Debug.getNativeHeapAllocatedSize()</code> and b) leads to an error </p> <pre><code>W/dalvikvm(26733): JNI: DeleteGlobalRef(0x462b05a0) failed to find entry (valid=1) </code></pre> <p>I am now thoroughly confused, I thought I at least understood the C++ side of things... Why is free() not returning the memory? And what am I doing wrong with the <code>DeleteGlobalRef()</code>?</p>

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