読書会(Java 11 and 12 - New Features)第2回議事録

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Java読書会BOF 「Java 11 and 12 - New Features」を読む会第2回
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"日時","2019年7月6日 10:00 - 17:00"
"場所","川崎市幸区幸市民館第４会議室"
"出席者(敬称略)","高橋(徹)、高橋(智)、藪下、今井、和田、平山、岩室、遠藤、大部(書記)"

Section 1: JDK 10
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Chapter 3: Garbage Collector Optimizations
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  Paralell full GC for G1(JEP 307)
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* https://openjdk.java.net/jeps/307

    The design goals of G1 GC
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- msはmsec(milli second)のこと

    G1 memory
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- Humongous:やたらでっかい、途方もない、問う意味　(読み:ヒューモンガス)
- １つのブロックに入りきれないオブジェクト、64MB超え

    Sample code
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- なぜサイズが999999なのだろうか、1000000で無い理由は？
- 連続したbyteデータを作りたかった？
- Java 9以降G1がデフォルトGC
- -Xlog:gc*はJava 9からのオプション

    G1 GC logs
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- 36->0(20)の20は何か
- logからはOutOfMemoryErrorになったことはわからない？

  Summary
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Chapter 4: Miscellaneous Improvements in JDK 10
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  Technical requirements
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  Mapping JDK 10 features with scopes and JEPs
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    Consolidationg the JDK forest into a single repository
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- JEP 296
* https://openjdk.java.net/jeps/296
- 内部実装の変更:JDKのソースが複数のリポジトリだったのをシングルリポジトリにした

    Thread-local handshakes
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- JEP 312
* https://openjdk.java.net/jeps/312
- プログラマは気にしない

    Removal of the Native-Header Generation Tool (javah)
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- JEP 313
* https://openjdk.java.net/jeps/313
- Cのヘッダーとコードを書いてくれる
- Java 10でなくなる

    Additional Unicode language-tag extensions
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- JEP 314
* https://openjdk.java.net/jeps/314
- BCP 47: Tags for Identifying Languages
* https://tools.ietf.org/html/bcp47

    Heap allocation on alternative memory devices
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- JEP 316
* https://openjdk.java.net/jeps/316

- 誤植: P59: 7行目: ExceptionではなくError
- OutOfMemoryException -> OutOfMemoryError

- NV-DIMM(non-volatile dual in-line memory module): 不揮発性DIMM
- レイテンシが大きい
- 大容量で遅い

    The experimental Java-based JIT copmiler
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- JEP 317
* https://openjdk.java.net/jeps/317
- Oracleはギリシャ神話、神託
- Graalは聖杯伝説（フランス語）
- 由来は宿題

    Root certificates
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- JEP 319
* https://openjdk.java.net/jeps/319
- OpenJDKにはない
- 自分で作って配ってる？

    Time-based release versioning
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- JEP 322
* https://openjdk.java.net/jeps/322
- セマンティックバージョニング
* https://semver.org/lang/ja/

  Summary
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Section 2: JDK 11
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- 誤植: P.ii: Section2が重複している
- Section2:Section2 -> Section2

Chapter 5: Local Variable Syntax for Lambda Parameters
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  Technical requirements
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  Lambda expressions
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    Explicitly-typed lambda expressions
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    Implicitly-typed lambda expressions
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  Lambda parameters and type inference with var
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    Adding var to lambda parameters
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- 誤植: P.69: 10行目: can't -> canでは？
- P.70: next chapterはHTTP Client APIではない

    Adding annotations to lambda parameters
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Chapter 6:  Epsilon GC
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  Technical requirements
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  The motivation behind Epsilon GC
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- 誤植: P.72: 3行目: canが1つ多い
- So, how can can -> So, how can

    Features of Epsilon
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- 誤植: P.72: 下から11行目: head dump -> heap dumpか？

      Latency and application performance
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        GC-induced overheads versus system overheads
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      Extremely short-lived work
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  Getting started with the HelloEpsilon GC class
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    Which memory area does GC collect - stack or heap?
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  Memory pressure testing with Epsilon
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  Desiging a garbage-free application
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    VM interface testing
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  Summary
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Chapter 7: The HTTP Client API
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  Technical requirements
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  A quick flashback
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    What can you do with HTTP?
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      The need for the HTTP Client API
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      HTTP Client usage
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- 誤植: P.84: 下から9行目: classをinterfaceにする
- The HttpResponce class -> The HttpResponce interface

    A basic example
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    The HttpClient class
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      Creating an HttpClient instance
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- 誤植: P.86: 13行目: newがgetになっている
- getHttpClient() -> newHttpClient()

- 誤植: P.86: 19行目: newがない、最後のピリオド不要
- = HttpClient.builder(). -> = HttpClient.newBuilder()

- 誤植: P.86: 下から3行目: newがない、最後のピリオド不要
-  = HttpClient.builder(). -> = HttpClient.newBuilder()

- 誤植: P.86: 下から1行目: 最後のカンマ不要
- (Redirect.NORMAL), -> (Redirect.NORMAL)

- 誤植: P.87: 8行目: 最後のピリオド不要
-  = HttpClient.newBuilder(). -> = HttpClient.newBuilder()

- 誤植: P.87: 10行目: Rを大文字にする、最後のカンマ不要
- .followRedirects(redirect.NORMAL), -> .followRedirects(Redirect.NORMAL)

      Methods of the HttpClient class
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      HttpRequest
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- POST()：大文字メソッド　java初？
- 誤植: P.91: 1行目: HttpClient -> HttpRequest
- 誤植: P.91: 表のヘッダーがここだけボールドじゃない
- 誤植: P.92: 11行目: Java type:strig -> Java type:String

      Httpresponse
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  Some examples
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    Accessing HTML pages using synchronous GET
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    Accessing HTML pages using asynchronous GET
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    Downloading multiple hosted image files
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- 誤植: P.92: 11行目: S大文字にする
- Java type:strig -> Java type:String

- P.97 ソースコードのインテンドが正しくない

- 宿題: Reactive Stream(Reactive Programing)は今どうなっているのか
- P.97の下から3行目 BodySubscriber. BodyBodySubscriberは、「.」で文が切れているので誤植では無い

    Posting form details
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  Summary
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.. note:: 次回は P.101 Chapter 8: ZGC から。

(以上)

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