RFR: 8340830: Console.readLine() and Console.printf() are mutually blocking [v5]

[Jaikiran Pai]

On Mon, 2 Feb 2026 22:05:03 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> Fixing an issue in Console where write is blocked if other thread is waiting to read, which is caused by unnecessary read/write locks. Removing those would solve the problem, as the read/write synchronization is performed at the StreamEn/Decoder level. One unrelated change is to refactor double-checked locking with LazyConstant.
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Added @requires condition

test/jdk/java/io/Console/ReadWriteBlockingTest.java line 51:

> 49:     public void testReadWriteBlocking() throws Exception {
> 50:         // check "expect" command availability
> 51:         var expect = Paths.get("/usr/bin/expect");

Nit - in recent times we have been using `Path.of(...)` instead of `Paths.get(...)`. `Paths.get(...)` is specified to merely invoke `Path.of(...)`.

test/jdk/java/io/Console/ReadWriteBlockingTest.java line 61:

> 59:         var jdkDir = System.getProperty("test.jdk");
> 60:         OutputAnalyzer output = ProcessTools.executeProcess(
> 61:             "expect",

Hello Naoto, is it intentional that we check for the presence of `/usr/bin/expect` but then rely on `PATH` when launching the `expect` process? Should this instead be `/usr/bin/expect`?

test/jdk/java/io/Console/ReadWriteBlockingTest.java line 66:

> 64:             jdkDir + "/bin/java",
> 65:             "-classpath", testClasses,
> 66:             "ReadWriteBlockingTest");

I think it's an oversight that the `-Djdk.console=jdk.internal.le` system property is being set in the `@run` of this test definition instead of being passed here to the launched `java` application. I think the test might have to be refactored a bit to have one single `@run ....` and then here in the test method launch the `java` main() with and without that system property.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29493#discussion_r2758247326
PR Review Comment: https://git.openjdk.org/jdk/pull/29493#discussion_r2758256127
PR Review Comment: https://git.openjdk.org/jdk/pull/29493#discussion_r2758281246