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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8273929: Remove GzipRandomAccess in heap dump test
From:       Lin Zang <lzang () openjdk ! java ! net>
Date:       2021-09-26 8:11:04
Message-ID: THkWpg-E0DMoydWtJP51HxUHMLcPR8U0C4q02QfwdGU=.e9362277-c763-43a9-a882-7561396aac49 () github ! com
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On Wed, 22 Sep 2021 20:24:09 GMT, Chris Plummer <cjplummer@openjdk.org> wrote:

> > The class `GzipRandomAccess` is used to parse heap dump file generated from \
> > `jcmd`/`jmap` tools when testing. It has the limitation that only gzip file which \
> > has "blocksize" header field could be sucessfully parsed. We think this class can \
> > be removed for 2 reasons: 1. The gzip heap dump file generated by `jhsdb` command \
> > does not contain the "blocksize" header field, so the GzipRandomAccess can not \
> > parse the generated file successfully. 2. The `GzipInputStream` could be used \
> > instead and then gziped heap dump file generated from both `jcmd`/`jmap` and \
> > `jhsdb jmap` could be parsed using same logic. Options
> 
> test/lib/jdk/test/lib/hprof/parser/Reader.java line 99:
> 
> > 97:                 // Possible gziped file, try decompress it and get the stack \
> >                 trace.
> > 98:                 in.close();
> > 99:                 String deCompressedFile = "heapdump" + \
> > System.currentTimeMillis() + ".hprof";
> 
> Is it necessary to create a file with the decompressed output rather than just \
> stream the decompressed output to a FileInputStream?

Hi @plummercj, 
Sorry for late response, I tried to avoid using the decompressed file, but it seems \
not simple as I expected.  The reason is that at line 121, the HprofReader require \
the filename and it use this file to create a ReadBuffer internally, and a \
RandomAccessFile will be created using the filename.  So I think may be it is not \
easy to make the change here, and maybe we could track it using a new bug if \
necessary, which may change the HprofReader implementation. What do you think?

-------------

PR: https://git.openjdk.java.net/jdk/pull/5556


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