bool HarfBuzzShaperBase::isWordEnd(unsigned index)
{
    return index && isCodepointSpace(m_normalizedBuffer[index]) && !isCodepointSpace(m_normalizedBuffer[index - 1]);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.