On 26/02/2019 5:01 pm, Yasumasa Suenaga wrote:
2019年2月26日(火) 15:47 Thomas Stüfe <thomas.stu...@gmail.com>:
Hi David, Yasumasa,
Do we support connection to later VMs from earlier JDK tools?
I could not find the spec about this.
So I asked to serviceability folks before filing this to JBS :-)
Just to chime in on that, I do not know if it is specified but it is certainly
very handy in daily use. I often use old jcmd tools to connect to newer VMs. I
always thought that was a neat design.
I agree with Thomas,
but I think we can update protocol version and reject request(s) from
jcmd and other tools on earlier release.
That is not a decision to be taken lightly and one that requires a CSR
request. Simply allowing for an extra arg on the jmap histo subcommand
should not break all backward compatability.
I think this is a "simple" bug in the Linux (and possibly other) attach
listener logic. It should be reading a protocol "packet" with up to 4
arguments, but it should be perfectly fine to get a packet with fewer
than 4. The current code doesn't do that, but assumes the "packet" is
always the maximum size.
David
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I guess serviceability tools like a jhsdb are recommended in use with
same version.
Thanks,
Yasumasa
..Thomas
