RFR: 8358533: Improve performance of java.io.Reader.readAllLines [v9]

[Brian Burkhalter]

On Tue, 1 Jul 2025 15:10:33 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> test/jdk/java/io/Reader/ReadAll.java line 117:
>> 
>>> 115:             sb.setLength(0);
>>> 116:         }
>>> 117: 
>> 
>> Does one of these cases result in a *very very long line without a terminator"; something that would trigger the limits of ArraySupport.newLength at or near Integer.MAX_VALUE -  8?
>
> I don't know, but I doubt it. I will look into adding something.

With this change

--- a/test/jdk/java/io/Reader/ReadAll.java
+++ b/test/jdk/java/io/Reader/ReadAll.java
@@ -115,6 +115,8 @@ public static void setup() throws IOException {
             sb.setLength(0);
         }
 
+        strings.add(" ".repeat(Integer.MAX_VALUE/2));
+

the limit is reached but it doubles the test run time, at least on an M4 Max.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25863#discussion_r2178054383