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[jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()

  • From: Danny Coward < >
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  • Subject: [jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()
  • Date: Tue, 11 Dec 2012 10:25:37 -0800

Hi Scott,

OK, I think I understand. So the idea is to allow implementations to send messages in a batch in order to get a big performance gain for applications that send a lot of messages in a short amount of time and to allow an explicit way for developers to take advantage of that, if the batching optimization is in the implementation.

I think that sort of approach already fits under the async model we have: the async send operations allow implementations to make their own choice about when to send the message after the async send has been called. i.e.

sendString/sendBytes - send the message now (no batching)
sendStringByFuture() - send the message when the container decides to (possibly batching if it chooses to)

And I think with the flush() method, we would have allowed containers who choose to do batching under the existing model without the extra setBatching/setAutoflush() idea ?


- Danny



On 11/29/12 12:11 PM, Scott Ferguson wrote:
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On 11/29/12 11:34 AM, Danny Coward wrote:
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My apologies Scott, I must have missed your original request - I've logged this as issue 63.

Thanks.

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So auto flush true would require the implementation never keep anything in a send buffer, false would allow it ?

Not quite. It's more like auto-flush false means "I'm batching messages; don't bother sending if you don't have to." I don't think the wording should be "never", because of things like mux, or other server heuristics. It's more like "start the process of sending."

setBatching(true) might be a better name, if that's clearer.

When setBatching(false) [autoFlush=true] -- the default --  and an app calls sendString(), the message will be delivered (with possible buffering, delays, mux, optimizations, etc, depending on the implementation, but it will be delivered without further intervention from the app.)

When setBatching(true) [autoFlush=false], and an app calls sendString(), the message might sit in the buffer forever until the application calls flush().

sendPartialString would be unaffected by the flag; the WS implementation is free to do whatever it wants with partial messages.

Basically, it's a hint: setBatching(true) [autoFlush=false] means "I'm batching a bunch of messages, so don't bother sending the data if you don't need to until I call flush."

Does that make sense? I don't want to over-constrain implementations with autoFlush(true) either option. Maybe "batching" is the better name to avoid confusion. (But even batching=true doesn't require buffering. Implementations can still send fragments early if they want or even ignore batching=true.)
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It seems like a reasonable request - do you think the autoflush property is a per-peer setting / per logical endpoint / per container setting ? I'm wondering if typically developers will want to set this once per application rather than keep setting it per RemoteEndpoint.

I think it's on the RemoteEndpoint, like setAutoCommit for JDBC. It's easy to set in @WebSocketOpen, and the application might want to start and stop batching mode while processing.

-- Scott

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- Danny

On 11/28/12 3:28 PM, Scott Ferguson wrote:
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I'd like a setAutoFlush() and flush() on RemoteEndpoint for high performance messaging. Defaults to true, which is the current behavior.

The performance difference is on the order of 5-7 times as many messages in some early micro-benchmarks. It's a big improvement and puts us near the high-speed messaging like ZeroQ.


--
Danny Coward
Java EE
Oracle Corporation



--
Danny Coward
Java EE
Oracle Corporation


[jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()

Danny Coward 12/11/2012

[jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()

Scott Ferguson 12/11/2012

[jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()

Danny Coward 12/15/2012

[jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()

Scott Ferguson 12/15/2012

[jsr356-experts] Re: RemoteEndpoint setAutoFlush() and flush()

Danny Coward 12/20/2012
 
 
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