Hi Denghui,
I thought to add JMX client feature to jcmd in the past for similar purposes,
but I didn't because JMX URL is too complex to type into console :)
Your proposal is useful, but it means malicious users can inject arbitrary
code. I think we need to consider security, and existing framework like JMX
might help us.
Thanks,
Yasumasa
On 2021/10/08 10:09, Denghui Dong wrote:
Hi Yasumasa,
JVMTI.data_dump and DataDumpRequest can achieve the purpose of triggering.
IIUC, DataDumpRequest does not seem to be able to pass parameters.
And sometimes the action the user wants to trigger may not be a data dump.
In fact, I think that commands such as JFR.start/stop are such a mechanism,
triggered by `jcmd`, and finally callback to the java layer.
Denghui Dong
------------------------------------------------------------------
From:Yasumasa Suenaga <suen...@oss.nttdata.com>
Send Time:2021年10月8日(星期五) 07:45
To:董登辉(卓昂) <denghui....@alibaba-inc.com>; serviceability-dev
<serviceability-dev@openjdk.java.net>; hotspot-runtime-...@openjdk.java.net
<hotspot-runtime-...@openjdk.java.net>
Subject:Re: Extend jcmd to java application level
Hi Denghui,
I think you can do it with combination of JVMTI.data_dump dcmd and
DataDumpRequest event in JVMTI.
JVM(TM) Tool Interface 17.0.0 (oracle.com)
<https://docs.oracle.com/en/java/javase/17/docs/specs/jvmti.html#DataDumpRequest>
Thanks,
Yasumasa
On 2021/10/07 22:58, Denghui Dong wrote:
Hi team,
The `jcmd` command can be used to call some built-in diagnostic commands in
vm.
Can we consider extending it to the java layer like perf data, so that Java
developers can
customize their diagnostic commands and then call them through `jcmd`?
One application scenario I can think of for this extension is that some
statistical information
may be collected in a java application. Triggering the output of this
statistical information through
the `jcmd` command seems to me relative to other mechanisms that trigger
output (such as through
an HTTP service, or periodic Printing) is more convenient.
Any input is appreciated.
Thanks,
Denghui Dong
