RFR: JDK-8213214: Set -Djava.io.tmpdir= when running tests

[Alan Bateman]

On 16/06/2020 18:44, Erik Joelsson wrote:
> There are a lot of jtreg tests that use temporary files. These 
> temporary files add up over time and fill up the global temp 
> directories on our test systems. To tackle this, we should try to 
> redirect these temporary files into a directory controlled by the test 
> framework. Jtreg does not do this, but we can set -Djava.io.tmpdir 
> from RunTest.gmk. This will not prevent all temp files from being 
> created outside of the work dir, but at least most.
>
> I have found one test where this becomes an issue, 
> java/nio/file/Path/Misc.java on Windows when running in elevated mode 
> with the workspace on a subst drive. This looks like an actual issue 
> in the product, so I have filed a separate bug for it [1]. Since we 
> currently use subst in our distributed test system to get around 
> Windows path length issues, we are hitting this problem. While the bug 
> is being evaluated, I have implemented a workaround in the test so 
> that it is able to handle the known situation. I would like to have 
> someone from core-libs look at the workaround.
>
> Webrev: http://cr.openjdk.java.net/~erikj/8213214/webrev.01/
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8213214
subst is a legacy mechanism. We know from previous attempts to reconcile 
usage of subset with NTFS symbolic links creates surprises and 
inconsistencies. I don't object to putting a workaround in the test but 
I think more information is required, in particular the comment that 
'file' is guaranteed to be subst free? Can you expand on this? Some 
examples would be useful as it's not clear how subst is used in the 
environment, is it solely that java.io.tmpdir is set to something like 
S:\tmp and S: is mapped to some other location?

-Alan