Thank you! I’ve updated the PR accordingly and summarized the benchmarks in the description. Here’s the short version:
From: Alan Bateman <alan.bate...@oracle.com> Sent: Wednesday, April 2, 2025 5:52 AM To: Engebretson, John <jeng...@amazon.com>; Markus KARG <mar...@headcrashing.eu>; core-libs-dev@openjdk.org Subject: RE: [EXTERNAL] JDK-8352891 Performance improvements to ByteArrayOutputStream CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. On 31/03/2025 16:51, Engebretson, John wrote: Alan – is this what you have in mind: ByteArrayOutputStream.getInstance() // returns existing class ByteArrayOutputStream.getUnsynchronizedInstance() // returns subclass of BAOS that overrides the synchronization ByteArrayOutputStream.get<Scalable|Memory|Fast|Segmented>Instance() // returns the new class BAOS has been synchronized since JDK 1.0. While undocumented, it's possible that existing code depends on this 30 year behavior so I think we are stuck with it. The removal of biased locking has spurred on a few complaints that the class is needlessly synchronized. A static factory to return an unsynchronized BOAS would help but only if it isn't used with code that assumes all operations are synchronized. So I think we will have to look at the API docs for this. It's not clear that we need to have several implementation with different performance tradeoffs. So I think part of the exploration will be to see what usages perform better or worse, and whether having a parameter to specify the initial size or some hint of the max size would help the discussion. -Alan
