Is buffering needed when setting org.xml.sax.InputSource.InputSource?

[Marshall Schor <ms...@schor.com>]

This takes an input stream.  We pass it (at least in one case) an 
"unbuffered" input stream - should this be buffered?

-Marshall

Re: Is buffering needed when setting org.xml.sax.InputSource.InputSource?

[Adam Lally <al...@alum.rpi.edu>]

My understanding is that if one does reads like the
currently-checked-in FileUtils, where you read into a buffer of any
reasonable size, there is no additional advantage to using a
BufferedInputStream (you are essentially implementing buffering
yourself anyway).  The advantage comes if you want to use the 1-byte
read method, since this would be highly inefficient if you did not use
a BufferedInputStream to manage the buffer for you.

If Xerces didn't perform well when passed a FileInputStream, I'd say
that would be a bug in Xerces for sure.  It would be terrible to force
your users to create a BufferedInputStream every time they wanted to
parse something at a reasonable speed.

Tweaking buffer sizes could help I guess, feel free to do a test.  My
gut says the Xerces default will perform just fine, or somebody would
have changed it by now.

-Adam

On 2/12/07, Marshall Schor <ms...@schor.com> wrote:
> Adam Lally wrote:
> > I doubt it.  Is there something that led you to believe this would be
> > necessary?
>
> Just doing some code inspection and seeing this - that it is perfectly
> feasible to
> pass a buffered version of the input to this, and that the general
> contract for IO
> seems to imply that you should use buffering for performance considerations.
> But I see from some web surfing that the Xerces impl does some buffering,
> and you can set the buffer size via a property (do we do that?  default
> = 2k I think,
> and the Apache license is about 1K by itself :-) ).
>
> I guess some simple test would tell...
>
> Some web surfing turned up:
>
> Parsers like Apache Xerces have the ability to set the input buffer size:
>
> |// Set the chunk to read in by SAX
>   parser.setProperty("http://apache.org/xml/properties/input-buffer-size",
>       new Integer(2048));
>
> See also http://xerces.apache.org/xerces2-j/properties.html
> which gives some advice on how large to set this.
>
> |
>
> -Marshall
>
>

Re: Is buffering needed when setting org.xml.sax.InputSource.InputSource?

[Marshall Schor <ms...@schor.com>]

Adam Lally wrote:
> I doubt it.  Is there something that led you to believe this would be
> necessary?  

Just doing some code inspection and seeing this - that it is perfectly 
feasible to
pass a buffered version of the input to this, and that the general 
contract for IO
seems to imply that you should use buffering for performance considerations.
But I see from some web surfing that the Xerces impl does some buffering,
and you can set the buffer size via a property (do we do that?  default 
= 2k I think,
and the Apache license is about 1K by itself :-) ).

I guess some simple test would tell...

Some web surfing turned up:

Parsers like Apache Xerces have the ability to set the input buffer size:

|// Set the chunk to read in by SAX
  parser.setProperty("http://apache.org/xml/properties/input-buffer-size", 
      new Integer(2048));

See also http://xerces.apache.org/xerces2-j/properties.html
which gives some advice on how large to set this.

|

-Marshall

Re: Is buffering needed when setting org.xml.sax.InputSource.InputSource?

[Adam Lally <al...@alum.rpi.edu>]

I doubt it.  Is there something that led you to believe this would be
necessary?  Are you worried that the XML parser is reading one
character at a time from the stream?  That seems unlikely to me.

-Adam

On 2/11/07, Marshall Schor <ms...@schor.com> wrote:
> This takes an input stream.  We pass it (at least in one case) an
> "unbuffered" input stream - should this be buffered?
>
> -Marshall
>