RFR: 8281267: VM HeapDumper dumps array classes several times [v2]

[Alex Menkov]

On Wed, 9 Feb 2022 19:38:43 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   updated test
>
> test/hotspot/jtreg/serviceability/HeapDump/DuplicateArrayClassesTest.java line 58:
> 
>> 56:         String[][][] strArray = new String[0][][];
>> 57:         LingeredApp.main(args);
>> 58:         System.out.println("" + intArray + strArray);   // to be sure the classes are not unloaded
> 
> Use  Reference.reachabilityFence(<array>);

Fixed

> test/hotspot/jtreg/serviceability/HeapDump/DuplicateArrayClassesTest.java line 86:
> 
>> 84:             Process p = ProcessTools.startProcess("jcmd", new ProcessBuilder(launcher.getCommand()));
>> 85:             // If something goes wrong with heap dumping most likely we'll get crash of the target VM.
>> 86:             while (!p.waitFor(5, TimeUnit.SECONDS)) {
> 
> 5 seconds seems kind of short. Doesn't allow for occasional network hiccups.

Note that this is a cycle. It ensures target VM (theApp) is not terminated while jcmd (p) processes the command.
I had some experience in the past when jcmd didn't exit if target VM crashes.

> test/hotspot/jtreg/serviceability/HeapDump/DuplicateArrayClassesTest.java line 218:
> 
>> 216:     }
>> 217: 
>> 218:     // Reads the whole HPROF_GC_CLASS_DUMP record, returns closs ID.
> 
> "class ID"

Fixed.

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PR: https://git.openjdk.java.net/jdk/pull/7384