RFR: 8352533: Report useful IOExceptions when jspawnhelper fails [v3]

[Volker Simonis]

On Wed, 26 Mar 2025 17:31:47 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> When jspawnhelper fails for whatever reason, but more prominently due to [JDK-8325621](https://bugs.openjdk.org/browse/JDK-8325621), it will report the errors into stdout, but not to the relevant `IOException`. So, if the application is configured to only capture the exception logs (e.g. through `java.util.logging`), we will miss any output from `jspawnhelper`, and user would be left without a clue what have happened. We have seen customers spending weeks trying to figure out what went wrong.
>> 
>> It would be good to provide useful `IOException` when `jspawnhelper` fails. We already have a precedent with vmError [printing helpful suggestions](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/utilities/vmError.cpp#L422) when VM fails, we can do a similar thing here. 
>> 
>> I am very open to bike-shedding about the actual message :)
>> 
>> Additional testing:
>>  - [x] Ad-hoc experiments with breaking jspawnhelper
>>  - [x] macos-aarch64-server-fastdebug, `java/lang/Process java/lang/ProcessBuilder`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Pull message into a field

OK, looks good.

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Marked as reviewed by simonis (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24149#pullrequestreview-2718186709