RFR: 8222000: JFR: Process start event

Erik Gahlin erik.gahlin at oracle.com
Thu Mar 5 17:21:41 UTC 2020

Hi Roger,

Thanks for the feedback.

Runtime.exec doesn't take arg[0] as a separate parameter, so it may make 
sense to not split it up in the event. For example, if plan is to 
execute "hg clone url", but the user forgets to add "hg", then it will 
look as if "clone" is the command, which could be confusing.

I will change the field name to 'command' to make it consistent with the 
single arg form of Runtime.exec.

Regarding delimiters, I think there are two use cases. Making something 
easy for humans to read and making it unambiguous for machine parsing. 
Since comma, or comma space, might be part of an argument, it is still 
unsafe for a parser. It would be possible to add escape sequences, but 
then it would be even harder for humans to read, which I think is the 
main use case. If we in the future would add support for serializing a 
String[], we could add another field, i.e. commandArray, which would 
work for machines without special parse logic.

There is no ProcessEnd event today, but that is something that could be 
added in the future. The exit status could be useful.

Updated webrev:


On 2020-03-05 15:27, Roger Riggs wrote:
> Hi Erik,
> Would the event be more useful if the executable arg[0] was a separate 
> field from the arguments?
> Though I exect it depends on what is later evaluating the event fields.
> If all of cmdarrray is being joined, then the event field name is more 
> appropriately
> called 'command';  similar to the single arg form of Runtime.exec and 
> new ProcessBuilder(...).
> A small point but the joining with ' ' space has the usual problem of 
> trying to parse out the arguments later.
> using ',' comma might be less ambiguous.  (and Arrays.toString).
> Otherwise, looks fine to me.
> Is there already a Process exited event? Its not quite as convenient 
> to instrument but useful if it captures the exit status. (ProcessImpl 
> - Windows and Linux versions).
> Roger
> On 3/5/20 9:10 AM, Erik Gahlin wrote:
>> Hi
>> Could I have review of a JFR event that is emitted when a process is 
>> started from Java.
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8222000
>> Webrev:
>> http://cr.openjdk.java.net/~egahlin/8222000/
>> Testing:
>> tier1,tier2 + jdk/jdk/jfr
>> Thanks
>> Erik

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