RFR: 8269886: Inaccurate error message for compressed hprof test [v5]

[Chris Plummer]

On Thu, 8 Jul 2021 03:28:10 GMT, Lin Zang <lzang at openjdk.org> wrote:

>> The current implementation of hprof Reader for testing always prompts "Can not decompress the compressed hprof file" when there is error for testing gzipped heap dump. This is inaccurate if the gzipped file was decompressed successfully but the hprof file format is incorrect. So the inaccurate error message could be misleading for issue analysis.
>> 
>> This trivial PR refine the error message by simply print "Can not get stack trace from the compressed hprof file", the underlying exception from GZIPInputStream() or HprofReader() would give accurate error info.
>
> Lin Zang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   donot wrap the exception from HprofReader

Looks good other than cleaning up the exception message.

test/lib/jdk/test/lib/hprof/parser/Reader.java line 178:

> 176:                         return r.printStackTraces();
> 177:                     } else {
> 178:                         throw new IOException("Unrecognized magic number of decompressed data: " + i);

"of decompressed data" just doesn't sound right. I'd suggest either removing it, or maybe instead say "...found in decompressed data".

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Changes requested by cjplummer (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4685