JDK-8352891 Performance improvements to ByteArrayOutputStream

[Engebretson, John]

  Thank you Brian, I’m sorry I missed this point!  The hint in this case is the parameter on the overloaded constructor; if set high enough, the initially-allocated buffer will guarantee exactly one array allocation with no growth.  This is identical to the ByteArrayOutputStream behavior described on [1].
  However, both issues focus on the far more common case of not knowing the final payload size, or perhaps making a bad guess; [1] attempts to modify the scale while [2] rewrites the data structure for greater gain.
     John

From: core-libs-dev <core-libs-dev-retn at openjdk.org> On Behalf Of Brian Burkhalter
Sent: Friday, April 4, 2025 3:31 PM
To: core-libs-dev at openjdk.org
Subject: RE: [EXTERNAL] JDK-8352891 Performance improvements to ByteArrayOutputStream


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I did not notice that Alan’s comment below, about adding a hint as to the maximum expected size, has been specifically addressed anywhere in this discussion. It might not be all that pertinent to the main thread of discussion, however, but it would certainly be useful for the issue [1], which I linked to [2].

Brian

[1] https://bugs.openjdk.org/browse/JDK-8329287
[2] https://bugs.openjdk.org/browse/JDK-8353729


On Apr 2, 2025, at 3:52 AM, Alan Bateman <Alan.Bateman at oracle.com<mailto:Alan.Bateman at oracle.com>> wrote:

[…] and whether having a parameter to specify the initial size or some hint of the max size would help the discussion.

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