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[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

  • From: Mark Thomas <markt@...>
  • To: jsr340-experts@...
  • Subject: [servlet-spec users] [jsr340-experts] Re: NIO specification clarification
  • Date: Wed, 10 Apr 2013 21:25:21 -0400
  • List-id: <jsr340-experts.servlet-spec.java.net>

On 10/04/2013 18:45, Rajiv Mordani wrote:

On 4/10/13 6:50 AM, Rémy Maucherat wrote:
On 04/10/2013 03:50 AM, Mark Thomas wrote:
I've been looking in detail at the NIO changes and have a couple of
questions. In section 3.7 we have the following:

The Servlet container must access methods in ReadListener in a thread
safe manner.

There is equivalent text in section 5.3:

The Servlet container must access methods in WriteListener in a
thread safe manner.


I recall some discussions around this area but not this exact
language. It is not clear to me how one accesses a method in a thread
safe manner since thread safety is a property of the method
implementation not of how it is accessed. A search of the archives
did not provide any illumination either. So, I have two questions.

Q1. What exactly does the above mean?

Q2. Why was this requirement added?
I think this is supposed to mean that there should be only one
container thread doing actions related to a particular request
processing, such as calling the read/write listeners, invoking async
dispatches, etc. If that is correct, the statement could be more precise.

Yes that is correct. Am happy to add a clarification to this but just so
everyone knows we have submitted for final approval ballot so we need to
either decide today what we want to replace this with or wait for an MR
to clarify this.

OK. That covers that what it is meant to mean but doesn't address the why.

The issue that caused me to look at this is Tomcat's WebSocket implementation. I am trying to make it container neutral and just use the Servlet 3.1 API.

The problem I have is that WebSocket requires some writes to be blocking and some non-blocking. With the above limitation I don't see a way to do this. If a container thread does something that triggers a blocking write that can't complete immediately I need a second container thread to call onWritePossible() to enable the first thread to continue.

If there is a good reason for this limitation then I'll have to give up on my container neutral implementation and use container specific APIs to control the blocking as that will enable me to implement it with the single container thread limitation.

Mark


[servlet-spec users] [jsr340-experts] NIO specification clarification

Mark Thomas 04/10/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Rémy Maucherat 04/10/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Rajiv Mordani 04/10/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Mark Thomas 04/11/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Rajiv Mordani 04/11/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Mark Thomas 04/12/2013

[servlet-spec users] [jsr340-experts] Re: Re: NIO specification clarification

Rajiv Mordani 04/12/2013

[servlet-spec users] [jsr340-experts] Re: Re: NIO specification clarification

Mark Thomas 04/12/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Rémy Maucherat 04/12/2013

[servlet-spec users] [jsr340-experts] Re: NIO specification clarification

Mark Thomas 04/12/2013

[servlet-spec users] [jsr340-experts] Re: Re: NIO specification clarification

Rémy Maucherat 04/12/2013

[servlet-spec users] [jsr340-experts] Re: Re: NIO specification clarification

Mark Thomas 04/29/2013

[servlet-spec users] [jsr340-experts] Re: Re: Re: NIO specification clarification

Rémy Maucherat 04/29/2013

[servlet-spec users] [jsr340-experts] Re: Re: Re: Re: NIO specification clarification

Mark Thomas 04/30/2013
 
 
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