RFR: JDK-8177763: Getting an hprof dump via jcmd could benefit from stronger option checking

[Gary Adams]

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/
>>>
>>>
>>
>
>