如何在 Android 的 Renderscript 中释放 memory？

Question

Profiler in Android Studio shows that my Renderscript app has memory leak in Graphics memory. I wrote some test code and successfully reproduce the problem, but I don't know how to solve it.

Renderscript code

void memoryTest(rs_allocation output) {
    rs_allocation tmp;
    for(int i = 0; i < 10; i++) {
        tmp = rsCreateAllocation_char(1000, 1000);
    }
}

Kotlin code

val rs: RenderScript = RenderScript.create(this)
while (true) {
    val script = ScriptC_singlesource(rs)
    val outputAllocation = Allocation.createTyped(rs, Type.createXY(rs, Element.I16(rs), 1000, 1000))
    script.invoke_memoryTest(outputAllocation)
    outputAllocation.destroy()
    script.destroy()
}

Memory usage I ended the run at 15 seconds, that's why memory went down.

I tried free(tmp) , delete tmp , delete(tmp) , all results in compile error. I want to know how to free up the memory of rs_allocation created inside Renderscript.

Edit

I tried rsClearObject(rs_allocation*) , the Renderscript became

void memoryTest(rs_allocation output) {
    rs_allocation tmp;
    for(int i = 0; i < 10; i++) {
        rsClearObject(&tmp);
        tmp = rsCreateAllocation_char(1000, 1000);
    }
}

It didn't solve the problem. The memory usage remains the same. It doesn't seem to have any effect.

Answer 1

Finally solved it. You just need to use another variable inside the loop to create the rs_allocation , and then pass it to the outside variable.

void memoryTest(rs_allocation output) {
    rs_allocation tmp;
    for(int i = 0; i < 10; i++) {
        rs_allocation tmp2 = rsCreateAllocation_char(1000, 1000);
        tmp = tmp2;

        //In my case tmp is a global variable used to pass value to kernel functions,
        //so it has to be outside.
        somefunctionThatUseTmp();
    }
}

I can't explain why this works, it defies my understanding of how pointers work in C.