Context Reallocate fails to allocate memory

[jarutis]

Hi,

I wanted to write an UDA which accumulates values and does some calculation in the final step. This works fine for very small samples. But `context->Reallocate' fails at arround 4MB. It returns a valid pointer but with allocated only 56 bytes.

Here is my Update code which accumulates values.

void DistributionUpdate(FunctionContext* context, const DoubleVal& input,
                        const IntVal& bins, StringVal* val) {
  if (input.is_null) return;
  DistributionStruct* dist = reinterpret_cast<DistributionStruct*>(val->ptr);

  if(dist->count >= dist->capacity) {
    dist->capacity += ELEMENT_ALLOCATION_SIZE;
    int new_size = val->len + dist->capacity * sizeof(double);
    val->ptr = context->Reallocate(val->ptr, new_size);
  }
  dist->elements[dist->count++] = input.val;
  dist->bins = bins.val;
}

If I debug this and check what is allocated versus what I expect to get allocated I get:

--TESTING NULL--
--TESTING 10 VALUE SAMPLE--
--TESTING NULL VALUE SAMPLE--
--TESTING COUNT < BINS--
--TESTING COUNT == BINS--
--TESTING 1000 UNSORTED VALUE SAMPLE--
--TESTING 1.000.000 VALUE SAMPLE--
[Reallocating old size:] Message: 800040
[Reallocating expected new size:] Message: 1600032
[Reallocating allocated new size:] Message: 1600040
[Reallocating old size:] Message: 1600040
[Reallocating expected new size:] Message: 2400032
[Reallocating allocated new size:] Message: 2400040
[Reallocating old size:] Message: 2400040
[Reallocating expected new size:] Message: 3200032
[Reallocating allocated new size:] Message: 3200040
[Reallocating old size:] Message: 3200040
[Reallocating expected new size:] Message: 4000032
[Reallocating allocated new size:] Message: 4000040
[Reallocating old size:] Message: 4000040
[Reallocating expected new size:] Message: 4800032
[Reallocating allocated new size:] Message: 56
Segmentation fault

Am I hitting some kind of limits, what am I missing here?

My full code is here:
https://gist.github.com/jarutis/7bb4e93a137607607a42