Jython

On Mon, 2009-01-05 at 00:02 -0600, Devin Venable wrote:
> Any insights into running a jython script as a daemon on Linux?  I
> realize that you cannot spawn processes, so true forking is out of the
> question.
> Let me retrace my steps, and jump in if you see a place to make a
> suggestion.
> 1. I wrote a SimpleXMLRPCServer that runs forever.  
> 2. For my purposes, I want to run it as a Linux service, so I worked
> up an init script, but was quickly reminded that, to run as a service,
> the program should fork and exit.

I've written long-running Jython processes that sit as services on
LINUX.  I just start them with "nohup {jythonApp} &".  Seems to work OK.
Only downside is that there is no way (AFAIK) to capture the PID of the
new process to store in /var/run/{jythonApp}.pid.  So "service
{jythonApp} stop" doesn't work.

>From a Shell script there is no way to capture launched process id??

On 1/5/09, Adam Tauno Williams <adam@...> wrote:
> On Mon, 2009-01-05 at 00:02 -0600, Devin Venable wrote:
>> Any insights into running a jython script as a daemon on Linux?  I
>> realize that you cannot spawn processes, so true forking is out of the
>> question.
>> Let me retrace my steps, and jump in if you see a place to make a
>> suggestion.
>> 1. I wrote a SimpleXMLRPCServer that runs forever.
>> 2. For my purposes, I want to run it as a Linux service, so I worked
>> up an init script, but was quickly reminded that, to run as a service,
>> the program should fork and exit.
>
> I've written long-running Jython processes that sit as services on
> LINUX.  I just start them with "nohup {jythonApp} &".  Seems to work OK.
> Only downside is that there is no way (AFAIK) to capture the PID of the
> new process to store in /var/run/{jythonApp}.pid.  So "service
> {jythonApp} stop" doesn't work.
>
>
> ------------------------------------------------------------------------------
> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>

-- 
Sent from my mobile device

" Logic merely sanctions the conquests of the intuition."
Jacques Hadamard

On Mon, 2009-01-05 at 09:18 -0500, Mohamed Lrhazi wrote:
> From a Shell script there is no way to capture launched process id??

"there is no way (AFAIK) to capture the PID" :)

Emphasis on the AFAIK, although I've been doing the UNIX thing for 1.6
decades (which is scary to think about).

> On 1/5/09, Adam Tauno Williams <adam@...> wrote:
> > On Mon, 2009-01-05 at 00:02 -0600, Devin Venable wrote:
> >> Any insights into running a jython script as a daemon on Linux?  I
> >> realize that you cannot spawn processes, so true forking is out of the
> >> question.
> >> Let me retrace my steps, and jump in if you see a place to make a
> >> suggestion.
> >> 1. I wrote a SimpleXMLRPCServer that runs forever.
> >> 2. For my purposes, I want to run it as a Linux service, so I worked
> >> up an init script, but was quickly reminded that, to run as a service,
> >> the program should fork and exit.
> > I've written long-running Jython processes that sit as services on
> > LINUX.  I just start them with "nohup {jythonApp} &".  Seems to work OK.
> > Only downside is that there is no way (AFAIK) to capture the PID of the
> > new process to store in /var/run/{jythonApp}.pid.  So "service
> > {jythonApp} stop" doesn't work.

I am sorry... I was mistaken... thought it was straightforward.... like:

start-my-process&
mypid=$SOME_SPECIAL_SHELL_VAR

but it looks like there is no such env var... or is there? i was
thinking $$, but of course that "my own pid"

My shell, Zsh, does display the process ID of the just-launched-job,
but did not check the man page if that pid is also stored in an env or
not.

Mohamed.

On Mon, Jan 5, 2009 at 11:04 AM, Adam Tauno Williams
<adam@...> wrote:
> On Mon, 2009-01-05 at 09:18 -0500, Mohamed Lrhazi wrote:
>> From a Shell script there is no way to capture launched process id??
>
> "there is no way (AFAIK) to capture the PID" :)
>
> Emphasis on the AFAIK, although I've been doing the UNIX thing for 1.6
> decades (which is scary to think about).
>
>> On 1/5/09, Adam Tauno Williams <adam@...> wrote:
>> > On Mon, 2009-01-05 at 00:02 -0600, Devin Venable wrote:
>> >> Any insights into running a jython script as a daemon on Linux?  I
>> >> realize that you cannot spawn processes, so true forking is out of the
>> >> question.
>> >> Let me retrace my steps, and jump in if you see a place to make a
>> >> suggestion.
>> >> 1. I wrote a SimpleXMLRPCServer that runs forever.
>> >> 2. For my purposes, I want to run it as a Linux service, so I worked
>> >> up an init script, but was quickly reminded that, to run as a service,
>> >> the program should fork and exit.
>> > I've written long-running Jython processes that sit as services on
>> > LINUX.  I just start them with "nohup {jythonApp} &".  Seems to work OK.
>> > Only downside is that there is no way (AFAIK) to capture the PID of the
>> > new process to store in /var/run/{jythonApp}.pid.  So "service
>> > {jythonApp} stop" doesn't work.
>
>
> ------------------------------------------------------------------------------
> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>



-- 
" Logic merely sanctions the conquests of the intuition."
Jacques Hadamard

On 5 Jan 2009, at 16:04, Adam Tauno Williams wrote:

> "there is no way (AFAIK) to capture the PID" :)
>
> Emphasis on the AFAIK, although I've been doing the UNIX thing for 1.6
> decades (which is scary to think about).

I tend to do the start/stop thing with a rather ugly combination of ps  
auxww, grep and grep -v.

A cleaner way might be to exec the launch in a (sub)-shell, and use  
that to pass "$$" in as
a command-line argument.

	-- N.


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In bash, use $!

Mohamed Lrhazi wrote:
> I am sorry... I was mistaken... thought it was straightforward.... like:
>
> start-my-process&
> mypid=$SOME_SPECIAL_SHELL_VAR
>
> but it looks like there is no such env var... or is there? i was
> thinking $$, but of course that "my own pid"
>
> My shell, Zsh, does display the process ID of the just-launched-job,
> but did not check the man page if that pid is also stored in an env or
> not.
>
> Mohamed.
>
> On Mon, Jan 5, 2009 at 11:04 AM, Adam Tauno Williams
> <adam@...> wrote:
>   
>> On Mon, 2009-01-05 at 09:18 -0500, Mohamed Lrhazi wrote:
>>     
>>> From a Shell script there is no way to capture launched process id??
>>>       
>> "there is no way (AFAIK) to capture the PID" :)
>>
>> Emphasis on the AFAIK, although I've been doing the UNIX thing for 1.6
>> decades (which is scary to think about).
>>
>>     
>>> On 1/5/09, Adam Tauno Williams <adam@...> wrote:
>>>       
>>>> On Mon, 2009-01-05 at 00:02 -0600, Devin Venable wrote:
>>>>         
>>>>> Any insights into running a jython script as a daemon on Linux?  I
>>>>> realize that you cannot spawn processes, so true forking is out of the
>>>>> question.
>>>>> Let me retrace my steps, and jump in if you see a place to make a
>>>>> suggestion.
>>>>> 1. I wrote a SimpleXMLRPCServer that runs forever.
>>>>> 2. For my purposes, I want to run it as a Linux service, so I worked
>>>>> up an init script, but was quickly reminded that, to run as a service,
>>>>> the program should fork and exit.
>>>>>           
>>>> I've written long-running Jython processes that sit as services on
>>>> LINUX.  I just start them with "nohup {jythonApp} &".  Seems to work OK.
>>>> Only downside is that there is no way (AFAIK) to capture the PID of the
>>>> new process to store in /var/run/{jythonApp}.pid.  So "service
>>>> {jythonApp} stop" doesn't work.
>>>>         
>> ------------------------------------------------------------------------------
>> _______________________________________________
>> Jython-users mailing list
>> Jython-users@...
>> https://lists.sourceforge.net/lists/listinfo/jython-users
>>
>>     
>
>
>
>

In the end I decided to use the daemon utility (man daemon) to start and
stop the jython daemon by unique name.

To start...

 daemon --name jybridge jython /opt/mypath/myprogram.py

To stop...

 daemon --name jybridge

Devin

On Mon, Jan 5, 2009 at 10:37 AM, Jeff Emanuel <jemanuel@...> wrote:

> In bash, use $!
>
> Mohamed Lrhazi wrote:
> > I am sorry... I was mistaken... thought it was straightforward.... like:
> >
> > start-my-process&
> > mypid=$SOME_SPECIAL_SHELL_VAR
>

Devin,

This sounds like the best course of action, you need to use some form of
external daemonization, whether the poor man's (and portable) nohup or
daemon.

For the record, os.fork in CPython is a versatile tool that's not at all
readily implementable for Jython, due to underlying limitations in the JVM.
(Others may wish to look at this problem again.) However, it's possible to
identify subsets of fork's functionality and implement an emulation. Jason
Briggs' pseudofork is just one example, although I believe it's possible now
to manipulate the triple of (thread, PythonInterpreter, and PySystemState)
more succinctly; see for example the function exec_code_separately in
test_sys_jy.py (
http://fisheye3.atlassian.com/browse/~raw,r=5806/jython/trunk/jython/Lib/test/test_sys_jy.py
).

Lastly, I'd suggest a more Jythonic solution to put this all together.
http://bugs.python.org/issue1745722 shows how run SimpleXMLRPCServer in
WSGI. With modjy supporting WSGI, you can then run it any servlet container
of your choice, which generally would have decent daemonization wrappers for
this sort of thing (or use daemon), not to mention other management
functionality. If you wanted something lightweight, consider Hudson's
Winstone or Jetty.

- Jim

On Mon, Jan 5, 2009 at 12:28 PM, Devin Venable <venable.devin@...:

> In the end I decided to use the daemon utility (man daemon) to start and
> stop the jython daemon by unique name.
>
> To start...
>
>  daemon --name jybridge jython /opt/mypath/myprogram.py
>
> To stop...
>
>  daemon --name jybridge
>
> Devin
>
>
> On Mon, Jan 5, 2009 at 10:37 AM, Jeff Emanuel <jemanuel@...> wrote:
>
>> In bash, use $!
>>
>> Mohamed Lrhazi wrote:
>> > I am sorry... I was mistaken... thought it was straightforward.... like:
>> >
>> > start-my-process&
>> > mypid=$SOME_SPECIAL_SHELL_VAR
>>
>
>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>
>


-- 
Jim Baker
jbaker@...

Hi,

i just stumbled upon hashdot, which looks like a capable jvm launch-wrapper.

http://hashdot.sourceforge.net/

One of the features:

Daemonize

Hashdot supports a "hashdot.daemonize" and "hashdot.io_redirect"
properties, conveniently packaged in a provided "daemon" profile, to
invoke a script as a detached UNIX daemon process. This includes full
support for directing process STDERR and STDOUT (including JVM) to a
specified file.

Regards,
Dirk

I used this one before and worked well for me:

Java Service Wrapper http://wrapper.tanukisoftware.org/doc/english/index.html

Works for both Unix and Windows
Mohamed.


On Thu, Jan 8, 2009 at 5:46 AM, Dirk Vleugels <dvl@...> wrote:
> Hi,
>
> i just stumbled upon hashdot, which looks like a capable jvm launch-wrapper.
>
> http://hashdot.sourceforge.net/
>
> One of the features:
>
> Daemonize
>
> Hashdot supports a "hashdot.daemonize" and "hashdot.io_redirect"
> properties, conveniently packaged in a provided "daemon" profile, to
> invoke a script as a detached UNIX daemon process. This includes full
> support for directing process STDERR and STDOUT (including JVM) to a
> specified file.
>
> Regards,
> Dirk
>
> ------------------------------------------------------------------------------
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> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>



-- 
" Logic merely sanctions the conquests of the intuition."
Jacques Hadamard