RFR: 8284638: store skip buffers in InputStream Object [v2]

[Bernd Eckenfels]

If you consider doing benchmarks in detail maybe consider a static buffer, too? (Especially if it can be used in multiple implementations?)

Gruss
Bernd
--
http://bernd.eckenfels.net
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Von: core-libs-dev <core-libs-dev-retn at openjdk.java.net> im Auftrag von XenoAmess <duke at openjdk.java.net>
Gesendet: Wednesday, April 13, 2022 11:58:06 PM
An: core-libs-dev at openjdk.java.net <core-libs-dev at openjdk.java.net>
Betreff: Re: RFR: 8284638: store skip buffers in InputStream Object [v2]

On Wed, 13 Apr 2022 16:02:10 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>>> @AlanBateman You are correct about this. But I wonder if this be a problem, why Reader class can afford store a skip buffer for each Reader.
>>>
>>> Is there anything different in the situations about skipBuffer in Reader and InputStream?
>>
>> Maybe the skip buffer in Reader should be looked at too, esp. as it couldpotentially grow to 16k bytes. The concern with changing InputStream.skip is that there may be a lot more input streams than readers in use, esp. if there is an input stream for every socket connection.
>
>> @AlanBateman Is the concern about holding more memory sufficient to retain the buffer using a SoftReference so it can be freed eagerly?
>> These buffers are never read from, so are quite a waste, but at least they are only used when
>> the underlying stream overrides skip.
>
> Maybe but I think it needs some benchmarks to know if caching a byte[] will help or just bloat memory. If the InputStream is to a file or socket then maybe skip is dominated by the I/O rather than the array allocation and zero'ing.

@AlanBateman jmh test added

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PR: https://git.openjdk.java.net/jdk/pull/5872