presto-memory-context/src/main/java/io/prestosql/memory/context/SimpleLocalMemoryContext.java/SimpleLocalMemoryContext/close
class SimpleLocalMemoryContext:    @Override
    public synchronized void close()
    {
        if (closed) {
            return;
        }
        closed = true;
        parentMemoryContext.updateBytes(allocationTag, -usedBytes);
        usedBytes = 0;
    }