> For the complete documentation index, see [llms.txt](https://docs.ocha.ng/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ocha.ng/java_ad00_b828_c815_b9ac/nio.md).

# Java NIO

## 용도

* Direct memory access
* Block mediated bulk data transfers

## 장점

* select() 시스템 콜과 같은 기능 사용 가능
* 디스크에서 읽어온 데이터를 Kernel mode buffer 에서 User mode buffer로 복사하지 않고 바로 Network로 전송하는 것이 가능
* Non-blocking data access 가능

## 이슈

* 그러나 network 전송을 nQueue Provider에서 처리하고 있는 상황에서 과연 NIO를 써서 얻을 수 있는 이득이 있을까?

## 결론

* 지금 내 용도인 단순 파일 읽기에서는 오히려 자바의 기본적인 I/O보다도 성능이 좋지 않다. 사용하지 않아야 할 것 같다.

> In some cases NIO actually performs worse than basic Java I/O. For simple sequential reads and writes of small files, for instance, a straightforward streams implementation might be two or three times faster than the corresponding event-oriented channel-based coding. Also, non-multiplexed channels -- that is, channels in separate threads -- can be much slower than channels that register their selectors in a single thread. <http://www.javaworld.com/article/2078654/java-se/java-se-five-ways-to-maximize-java-nio-and-nio-2.html>


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ocha.ng/java_ad00_b828_c815_b9ac/nio.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.