RFR: 8307990: jspawnhelper must close its writing side of a pipe before reading from it

[Joe Darcy]

On Wed, 17 May 2023 14:42:45 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> > Should this issue have a CSR for any behavioral changes?
> 
> Well, you can certainly argue that every bug fix is a behavioral changes, right :)
> 
> But seriously, I don't see how this PR could require a CSR. The only behavioral change is really that `jspawnhelper` can now no longer block and deadlock. But that's exactly how it should have behaved in the first place.

Yes, some judgement is needed on behavioral changes; this was broached in portions of my recent talk to the JCP EC:

"Contributing to OpenJDK: Participating in stewardship for the long-term"
https://jcp.org/aboutJava/communityprocess/ec-public/materials/2023-04-12/Contributing_to_OpenJDK_2023_04_12.pdf

The process spawning code is apparently tricky and subtle, so much so that this will be apparently the third attempt at it since JDK 12. (I still have memories of various platform-specific issues in process handling from my time maintaining the launcher.)

So I don't think the applicability of a CSR for this change should be dismissed and personally I would prefer a change like this be made early in JDK 22 rather than a few weeks before JDK 21 rampdown; it is easier to address any bug tail early in 22 rather than late in 21.

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PR Comment: https://git.openjdk.org/jdk/pull/13956#issuecomment-1551975825