非同期JDBC呼び出しは可能ですか? 質問する

Question

JDBC 呼び出しをアクター、エグゼキューター、またはその他のものでラップする提案されたアプローチがここでどのように役立つのか理解できません。誰か説明してもらえますか。

確かに、基本的な問題は、JDBC 操作がソケット IO でブロックされることです。これが発生すると、実行中のスレッドがブロックされます。これで終わりです。どのラッピングフレームワークを使用するか選択しても、同時要求ごとに 1 つのスレッドがビジー状態/ブロック状態になります。

If the underlying database drivers (MySql?) offers a means to intercept the socket creation (see SocketFactory) then I imagine it would be possible to build an async event driven database layer on top of the JDBC api but we'd have to encapsulate the whole JDBC behind an event driven facade, and that facade wouldn't look like JDBC (after it would be event driven). The database processing would happen async on a different thread to the caller, and you'd have to work out how to build a transaction manager that doesn't rely on thread affinity.

Something like the approach I mention would allow even a single background thread to process a load of concurrent JDBC exec's. In practice you'd probably run a pool of threads to make use of multiple cores.

(Of course I'm not commenting on the logic of the original question just the responses that imply that concurrency in a scenario with blocking socket IO is possible without the user of a selector pattern - simpler just to work out your typical JDBC concurrency and put in a connection pool of the right size).

Looks like MySql probably does something along the lines I'm suggesting --- http://code.google.com/p/async-mysql-connector/wiki/UsageExample

Answer 1

JDBC 呼び出しをアクター、エグゼキューター、またはその他のものでラップする提案されたアプローチがここでどのように役立つのか理解できません。誰か説明してもらえますか。

確かに、基本的な問題は、JDBC 操作がソケット IO でブロックされることです。これが発生すると、実行中のスレッドがブロックされます。これで終わりです。どのラッピングフレームワークを使用するか選択しても、同時要求ごとに 1 つのスレッドがビジー状態/ブロック状態になります。

If the underlying database drivers (MySql?) offers a means to intercept the socket creation (see SocketFactory) then I imagine it would be possible to build an async event driven database layer on top of the JDBC api but we'd have to encapsulate the whole JDBC behind an event driven facade, and that facade wouldn't look like JDBC (after it would be event driven). The database processing would happen async on a different thread to the caller, and you'd have to work out how to build a transaction manager that doesn't rely on thread affinity.

Something like the approach I mention would allow even a single background thread to process a load of concurrent JDBC exec's. In practice you'd probably run a pool of threads to make use of multiple cores.

(Of course I'm not commenting on the logic of the original question just the responses that imply that concurrency in a scenario with blocking socket IO is possible without the user of a selector pattern - simpler just to work out your typical JDBC concurrency and put in a connection pool of the right size).

Looks like MySql probably does something along the lines I'm suggesting --- http://code.google.com/p/async-mysql-connector/wiki/UsageExample

非同期JDBC呼び出しは可能ですか? 質問する

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