RFR (M) JDK-6479360 - detailed dumping of class size statistics

Karen Kinnear karen.kinnear at oracle.com
Tue Jan 22 14:07:16 PST 2013


Thank you for doing this. I like the way you have the size collection in the file
with the metadata definitions.

1. diagnosticCommand.hpp line 200 - inspeactheap -> inspectheap

2. please update copyrights on all files you changed to 2013

3. I sent an email to the embedded folks to find out if they want this
   If they do ...

   - did you build with and without INCLUDE_SERVICES?
   What happens when you build with it off and run the jcmd ?
   I am confused that in diagnosticCommand.cpp ClassStatsDcmd is available without
   INCLUDE_SERVICES, but the actual details below the collect_statistics are not?
   Did you talk to the embedded team about whether they want this or not?

   - I would recommend that include files also add the new methods conditional
  on INCLUDE_SERVICES - you did that in some of them, but I think you missed:
  method.hpp, methodData.hpp, constantPool.hpp, constMethod.hpp, annotations.hpp

4. heapInspection.hpp line 56: is InstBytesi supposed to be InstBytes?

5. heapInspection.hpp line 122 - you have some funny "\" - is that intentional?

6. INT64_FORMAT: I think Harold just put back a change for julong handling
that switched to using JULONG_FORMAT- see KlassInfoHisto::print_class_stats - 2 places
(to ensure this also works on Mac OS/X)


On Jan 16, 2013, at 7:39 PM, Ioi Lam wrote:

> Please review:
>     http://cr.openjdk.java.net/~acorn/class_stats_010/
> Bug: RFE: PrintClassHistogram improvements
>     https://jbs.oracle.com/bugs/browse/JDK-6479360
> Sponsor: Karen Kinnear
> Summary:
> A new diagnostic command "jcmd GC.class_stats" is added. The user
> can invoke this command to connect to a live JVM and dump a detailed
> report of size statistics of all loaded classes (including array
> classes and anonymous classes).
>     ==========SYNOPSIS===================================
>     $ jcmd $PID help GC.class_stats
>     Provide statistics about Java class meta data.
>     Impact: High: Depends on Java heap size and content.
>     Syntax : GC.class_stats [options] [<columns>]
>     Arguments:
> 	columns : [optional] Comma-separated list of all the columns to
>                   show. If not specified, the following columns are shown:
>                   InstBytes,KlassBytes,CpAll,annotations,MethodCount,Bytecodes,
>                   MethodAll,ROAll,RWAll,Total (STRING, no default value)
>     Options: (options must be specified using the <key> or <key>=<value> syntax)
> 	-all : [optional] Show all columns (BOOLEAN, false)
> 	-csv : [optional] Print in CSV (comma-separated values) format for 
>                 spreadsheets (BOOLEAN, false)
> 	-help : [optional] Show meaning of all the columns (BOOLEAN, false)
>     ======================================================
> By default, the output is human-readable tabulated text format. The
> user can also select CSV format (comma-separated values) to be
> used with spreadsheets.
> A large number of columns are available. By default, a few "summary 
> columns" (e.g., size of Klass objects, total read-only data, etc) 
> are printed. The user can also manually select the columns.
> Please see the attachments in the bug for sample output, as well as
> a listing of all the columns and their meanings:
> https://jbs.oracle.com/bugs/browse/JDK-6479360?focusedCommentId=13290360&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13290360
> Impact:
> If this diagnostic command is not used, there should be no
> impact to the JVM's execution, except for
>    + libjvm.so footprint increase (about 10KB larger on Linux/x64)
>    + one additional virtual method in Klass.
> This feature is excluded when INCLUDE_SERVICES=0 (e.g., 
> embedded builds).
> Tests run:
> + JPRT -- (hotspot only) to verify build-ability
> + Manually ran "jcmd $PID help GC.class_stats" on Linux/x64
> + I intend to add a new testcase once this is committed:
>   https://jbs.oracle.com/bugs/browse/JDK-8006413
>   Add utility classes for writing better multiprocess tests in jtreg
> Thanks,
> Ioi

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