RFR: 8304745: Lazily initialize byte[] in java.io.BufferedInputStream [v2]

[Alan Bateman]

On Thu, 23 Mar 2023 19:41:24 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Sergey Tsypanov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update src/java.base/share/classes/java/io/BufferedInputStream.java
>>   
>>   Co-authored-by: liach <7806504+liach at users.noreply.github.com>
>
> src/java.base/share/classes/java/io/BufferedInputStream.java line 183:
> 
>> 181:         if (buffer == EMPTY) {
>> 182:             buf = buffer = new byte[size];
>> 183:         }
> 
> You should probably use compareAndSet here too like in fill() - to handle the case of asynchoronous close.
> This patch makes me a bit nervous. I would advise to get feedback from @bplb and @AlanBateman .

Yes, I'm nervous about changing BIS too. Most of the initial revisions of the patch introduced compatibility issues so it had to be restricted to the no sub-class case. Here, it needs to CAS buf as otherwise it will break async close. 

I think the starting point for this issue is to show examples where it avoids needing to create the byte[] on first usage. The first use of read, readAllBytes, readNBytes, .. will create the byte[] but Sergey may have spotted some usages where it does help.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13150#discussion_r1146756100