On Tue, 9 Jun 2026 16:15:08 GMT, Jaikiran Pai <[email protected]> wrote:

>> Can I please get a review of this change which proposes to address 
>> https://bugs.openjdk.org/browse/JDK-8385924?
>> 
>> For reasons explained in that issue, the `java.util.zip.GZIPInputStream` 
>> class currently behaves differently depending on which version of Java is in 
>> use. The change in this current PR proposes to introduce a system property 
>> which allows applications to decide whether they prefer the decades old 
>> behaviour of `GZIPInputStream` where it uses `InputStream.available()` for 
>> deciding whether to read a subsequent member in the stream, or whether the 
>> application prefers the more recent behaviour of `GZIPInputStream` where it 
>> skips the `available()` call and instead directly does a read operation for 
>> detecting a subsequent member.
>> 
>> The system property by default isn't set which means that `GZIPInputStream` 
>> will call `InputStream.available()` and thus matches its decades old 
>> behaviour. The introduction of this system property is a stopgap measure as 
>> noted in https://github.com/openjdk/jdk/pull/30925#discussion_r3318466104 :
>> 
>>> For JDK 27, introduce a system property that controls the reliable handling 
>>> of streams with more than one member. Long standing behavior does not 
>>> handle the case where the underlying stream doesn't have a useful 
>>> avaialble() method and it additionally swallows any exception when reading 
>>> ahead. The system property can be documented as an implNote in the 2-arg 
>>> constructor or class description. The property will need default to long 
>>> standing behavior (not the more recent/changed behavior).
>> 
>> As noted in that same comment, the long term solution involves enhancing the 
>> `GZIPInputStream` class to introduce a constructor which allows applications 
>> to decide how the `GZIPInputStream` should behave when dealing with multiple 
>> members:
>> 
>>> For JDK 28 or later, introduce a new constructor to create a 
>>> GZIPInputStream that works like it should have done in JDK 1.1 when the API 
>>> was originally introduced. We discussed two possible sets of parameters. We 
>>> also discussed maybe deprecating the two existing constructors due to the 
>>> issue of treating available==0 as EOF and the issue of swallowing 
>>> exceptions. 
>> 
>> That new API will need careful thought and time and thus the current 
>> proposal to introduce this system property in the meantime.
>> 
>> A new jtreg test has been introduced to verify the usage of this system 
>> property. A CSR will be proposed shortly. Existing tests and this new test 
>> continue to pass with this change.
>> 
>> ---------...
>
> Jaikiran Pai has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   minor adjustments based on Alan's review

OK, let's ship it.

-------------

Marked as reviewed by simonis (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/31396#pullrequestreview-4460631160

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