cr7154822 : Request for code review

[Frederic Parain]

Hi David,

I have a question about the 1024 bytes limit.
Have you tested this limit on the different platforms?
Because jcmd uses the attachAPI to send commands to
the target JVM and each platform uses a different mechanism
to implement the attachAPI (Solaris->door, Linux->socket,
Windows->Pipe). I can see the 1024 bytes limit on the
Windows implementation, but I don't see hard coded values
on other platforms. Do you know what is the limit for
each platform?

If the limit is the same for all platforms, then the fix
could be improved to check that each line is smaller than the
limit before to send it to the target JVM, and properly
report an error if it isn't. Right now, each platform
throws an IOException with a platform dependent message.
Instead, detecting lines exceeding the limit and printing
a clear message like:

"line 84: Line too long"

would improve the user experience.

A few comments on the code:

src/share/classes/sun/tools/jcmd/JCmd.java
	Copyright years should be "2011, 2012" instead of "2012"

test/sun/tools/jcmd/dcmd-big-script.txt
	The empty line at the end of the line might cause the
         VM to complain about an unknown diagnostic command

test/sun/tools/jcmd/jcmd-big-script.sh
	No comment


Regards,

Fred

On 03/29/12 06:28 AM, David Buck wrote:
> Hi!
>
> Please review my fix for the following bug :
>
> [ Bug ID: 7154822 forward port fix for Bug 13645891 to JDK8 jcmd (1024
> byte file size limit issue) ]
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7154822
>
> The issue is there is an arbitrary limit in the size of a script file
> you pass to the jcmd command (via the -f option) of 1024 bytes. The
> solution is for jcmd to break up the input file into individual lines
> and send them one at a time to the jvm.
>
> A similar fix has already been done for JRockit's jrcmd command and will
> be released in R28.2.3.
>
> [ jdk ]
> http://cr.openjdk.java.net/~dbuck/7154822/webrev.00/
>
> All the default jprt tests and the jdk_tools tests were run and passed.
>
> Cheers,
> -Buck

-- 
Frederic Parain - Oracle
Grenoble Engineering Center - France
Phone: +33 4 76 18 81 17
Email: Frederic.Parain at Oracle.com