RFR: 8269886: Inaccurate error message for compressed hprof test [v3]

[David Holmes]

On Wed, 7 Jul 2021 00:44:11 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 two additional commits since the last revision:
> 
>  - Throw exception when decompressed data has incorrect magic number
>    
>    Also remove unreachable code after exception is added.
>  - throw exception when magic number is incorrect in decompressed data

Either deleting the out file needs to be handled correctly in all cases or it should left as-is and fixed in a different RFE that also handles stream closing *try-with-resources?) etc. to clean up the code.

Otherwise the actual try/catch changes seem okay.

Thanks,
David

test/lib/jdk/test/lib/hprof/parser/Reader.java line 175:

> 173:                                               true, debugLevel);
> 174:                         r.read();
> 175:                         out.delete();

I thought this was going to handled by the separate RFE to fix the general logic? And you don't delete before throwing below. There should be a finally clause to handle deletion consistently.

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Changes requested by dholmes (Reviewer).

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