Here are the items I'd like to discuss.

   1. The current help doc only mention <filename>
       as a positional argument.
       The original bug was posted with an expectation
        that <filename=value> should be accepted.
       Do we document that we support either form
       in the help message?
       Do we change the issue type from bug to rfe?
       Do we need a CSR if the dcmd syntax is changed?

  2. Do we have a native function that will declare a
      path as absolute or relative to the current directory?
      Worried a little about windows paths here.

  3. Looks like minimal heap_dump testing here:
      open/test/hotspot/jtreg/serviceability/dcmd/gc/HeapDumpTest.java
...

On 8/29/18, 2:04 PM, Chris Plummer wrote:
Hi Gary,

Ok. Overall looks good. A couple of comments:

You now output the path of the created file, but in a kind of strange way. You print the CWD, and then the specified path, whether relative or full. So it's kind of confusing because if the user specifies a full path, they'll still see the CWD printed out. Why not just print the full path (after combining with CWD if needed), or maybe omit the CWD off when a full path was specified. If determining if CWD ends up getting used is difficult, maybe just make it more clear what you are printing is the CWD, and it is not necessarily part of the actual filename path.

What about writing some tests cases. It would probably be pretty easy to update some of the existing test cases to use key=<value> where previously they just allowed <value>.

thanks,

Chris


On 8/29/18 8:10 AM, Gary Adams wrote:
Sure no problem.

I have two workspaces I use called jdk-jdb and jdk-jdk.
I have the changes in the jdk-jdb workspace for the heap
filename updates.

In the jdk-jdb workspace a launch a process that just waits for input.

   jdk/bin/java -cp ~/classes my

In the jdk-jdk workspace I issue the jcmd to talk to the java process
running in the jdk-jdb workspace. The updated output includes
"[<current-directory>,<heap dump filename>]"

...

$  jdk/bin/jcmd 2328 GC.heap_dump filename=foo
2328:
Heap dump file created [/export/users/gradams/ws/jdk-jdb/build/linux-x64,foo]

$  jdk/bin/jcmd 2328 GC.heap_dump filename
2328:
Heap dump file created [/export/users/gradams/ws/jdk-jdb/build/linux-x64,filename]

$  jdk/bin/jcmd 2328 GC.heap_dump ffoo2
2328:
Heap dump file created [/export/users/gradams/ws/jdk-jdb/build/linux-x64,ffoo2]

$  jdk/bin/jcmd 2328 GC.heap_dump ffoo2
2328:
File exists [/export/users/gradams/ws/jdk-jdb/build/linux-x64,ffoo2]

$  jdk/bin/jcmd 2328 GC.heap_dump ~/ffoo2
2328:
Heap dump file created [/export/users/gradams/ws/jdk-jdb/build/linux-x64,/home/gradams/ffoo2]

$  jdk/bin/jcmd 2328 GC.heap_dump ~/ffoo2
2328:
File exists [/export/users/gradams/ws/jdk-jdb/build/linux-x64,/home/gradams/ffoo2]

$  jdk/bin/jcmd 2328 GC.heap_dump /tmp/ffoo2
2328:
Heap dump file created [/export/users/gradams/ws/jdk-jdb/build/linux-x64,/tmp/ffoo2]

$  jdk/bin/jcmd 2328 GC.heap_dump /tmp/ffoo2
2328:
File exists [/export/users/gradams/ws/jdk-jdb/build/linux-x64,/tmp/ffoo2]

$ pwd
/home/gradams/scratch/ws/jdk-jdk/build/linux-x64


On 8/29/18, 2:21 AM, Chris Plummer wrote:
Hi Gary,

What would be really useful are some before/after examples that demonstrate what has changed from the users point of view.

thanks,

Chris

On 8/28/18 5:26 AM, Gary Adams wrote:
This message may have been lost in the vacation email backlog, so I'm
sending it again.

On 8/9/18, 2:19 PM, Gary Adams wrote:
Thee are several reported problems using jcmd for obtaining heap dumps.

Some users are confused by the positional argument for a filename
when a similar jfr command uses "key=value" syntax.

Some users are confused by the basic nature of the command, where the jvm executing the heap dump is running in a different current directory than
the jcmd itself.

This is a proposed fix to report the current directory and the filename when the heap dump is successfully written or if an error occurs. There
is also a proposed fix to handle the case when the user provided
"key=value" inputs. If the key matches the argument name, then the
user intended the value to be used.

  Issue: https://bugs.openjdk.java.net/browse/JDK-8177763
  Webrev: http://cr.openjdk.java.net/~gadams/8177763/webrev.00/









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