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