If you just want to know if a particular JRE runs as a client or a
server, you can use, e.g., here on a machine that isn't a server-class
machine:
$ java -version
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b16)
Java HotSpot(TM) Client VM (build 1.7.0-ea-b16, mixed mode, sharing)
If you want to see why a particular JRE decides to run as a server,
you can use the relatively undocumented _JAVA_LAUNCHER_DEBUG environment
variable, e.g., here on a server-class machine:
$ _JAVA_LAUNCHER_DEBUG=true java -version
----_JAVA_LAUNCHER_DEBUG----
....
pages: 262144 page_size: 8192 physical memory: 2147483648 (2.000GB)
sysconf(_SC_NPROCESSORS_CONF): 2
unix_sparc_ServerClassMachine: JNI_TRUE
ServerClassMachine: returns default value of true
which implements the description in
http://java.sun.com/j2se/1.5.0/docs/guide/vm/server-class.html
Or if you want to look at the code that does that, start from
https://openjdk.dev.java.net/source/browse/openjdk/jdk/trunk/jdk/src/solaris/bin/ergo.c?rev=257&view=markup
and find the machine-dependent ServerClassMachineImpl for Solaris/SPARC
(because it's easy to understand) at
https://openjdk.dev.java.net/source/browse/openjdk/jdk/trunk/jdk/src/solaris/bin/ergo_sparc.c?rev=257&view=markup
The version of ServerClassMachineImpl for Solaris/i586 is in
https://openjdk.dev.java.net/source/browse/openjdk/jdk/trunk/jdk/src/solaris/bin/ergo_i586.c?rev=257&view=markup
and is *much* more exciting.
I'm pointing at the code for what will be JDK-7. If you are poking at
an older JDK, the code isn't arranged into files quite as nicely, but
the functions are about the same.
I don't know why anything in there would cause DTrace to hang. It's all
just user-land code. There is some assembler in the i586 implementation.
... peter
Naveen Nalam wrote:
> Hi,
>
> This command causes my server to hang:
> dtrace -n 'pid$target::ServerClassMachine:return {printf( "%d\n", arg1) }' -c
> /usr/bin/java
>
> I was running this command without any arguments to trace how Java was
> determining if it should run in client or server VM mode.
>
> The above command will hang the box either on the 1st execution, or I may
> have to run the command 4-5 times to get the server to hang. But I can always
> reproduce it. I thought perhaps it was bad hardware, so I tried on another
> server with the same specs and also get the hang. This however only hangs my
> storage servers, all my other server types (compute, web) are fine (which
> have different hardware config).
>
> Storage server specs:
> Asus P5M2 mobo
> Marvell MV8 controllers
> 6GB DDR2 DRAM
> Core2 Duo cpu
> Solaris S10 Update 4 with patch 125205-06 (sata fixes)
>
> There is no crash dump. I also tried booting the kernel with "-k", "set
> nopanicdebug=1", and "KEYBOARD_ABORT=alternate" -- but couldn't get the
> kernel to break into the debugger.
>
> If anyone has some suggestions, I can give them a try.
>
> Thanks,
> Naveen
>
>
> --
> This message posted from opensolaris.org
> _______________________________________________
> dtrace-discuss mailing list
> [email protected]
_______________________________________________
dtrace-discuss mailing list
[email protected]
