RFR: 8331987: Enhance stacktrace clarity for CompletableFuture CancellationException

[Chen Liang]

On Mon, 13 May 2024 16:41:37 GMT, Viktor Klang <vklang at openjdk.org> wrote:

> This change adds wrapping of the CancellationException produced by CompletableFuture::get() and CompletableFuture::join() to add more diagnostic information and align better with FutureTask.
> 
> Running the sample code from the JBS issue in JShell will produce the following:
> 
> 
> jshell> java.util.concurrent.CancellationException: 
> 	at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:392)
> 	at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2073)
> 	at REPL.$JShell$18.m2($JShell$18.java:10)
> 	at REPL.$JShell$17.m1($JShell$17.java:8)
> 	at REPL.$JShell$16B.lambda$main$0($JShell$16B.java:8)
> 	at java.base/java.lang.Thread.run(Thread.java:1575)
> Caused by: java.util.concurrent.CancellationException
> 	at java.base/java.util.concurrent.CompletableFuture.cancel(CompletableFuture.java:2510)
> 	at REPL.$JShell$16B.lambda$main$1($JShell$16B.java:11)
> 	... 1 more

src/java.base/share/classes/java/util/concurrent/CancellationException.java line 72:

> 70:      * @param cause the underlying cancellation exception
> 71:      */
> 72:     CancellationException(String message, CancellationException cause) {

Can we remove the message argument, which is always empty?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19219#discussion_r1598786142