RFR: 8279022: JCmdTestFileSafety.java should check file time stamp for test result

[Calvin Cheung]

On Tue, 21 Dec 2021 02:45:35 GMT, Yumin Qi <minqi at openjdk.org> wrote:

> When test finished, the created archive file should be checked after  the first run for existence, and checked for time stamp after second run.  Since the file name is same, this method is more accurate than the existing checking, only checking the existence of the file. Since jcmd can do repeat dynamic dump to same java process now, removed unnecessary restart process code.
> 
> Tests: tier1, jtreg on local linux-x64.
> 
> Thanks
> Yumin

Looks good. Just one comment.

test/hotspot/jtreg/runtime/cds/appcds/jcmd/JCmdTestFileSafety.java line 104:

> 102:             fileLocal.delete();
> 103:         }
> 104:         outputDirFile.setWritable(true);

Since you've added the `setWritable(true)` here, do you still need the existing one at line 116?

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PR: https://git.openjdk.java.net/jdk/pull/6904