Re: [Jython-users] Threads

[Kevin B. <kb...@ca...>]

Stephen Naicken wrote:
> 
> I'm not sure as to how to go about threading a jython program.  I am
> trying to use from java.lang import Thread, extending the Thread class
> and overriding thr run method.  However, when I do this in jython, I get
> an error telling me the __call__ attribute has not been set.

As a design principle, it is often better to implement Runnable rather than extending Thread (you have Runnable jobs to do, rather than anything that would change the semantics of a Thread).

> If anyone can provide a small example of how to create a threaded app in
> jython I would be very grateful.

Four small examples (Jython tends to violate Python's "one obvious way to do it" principle), ordered as Python over Java, then preferred over less preferred:

def greet( name ):
    print "greetings", name

count = 0

# newer Python way
import threading
count += 1
t = threading.Thread(
    target=greet,
    name="MyThread %d" % count,
    args=( "threading.Thread", )
    )
t.start()

# older Python way
# has no thread naming feature
import thread
thread.start_new_thread(
    greet,
    ( "thread.start_new_thread", )
    )

# preferred Java way
from java.lang import Thread, Runnable
class GreetJob( Runnable ):
    def __init__( self, name ):
        self.name = name
    def run( self ):
        greet( self.name )
count += 1
t = Thread( GreetJob( "Runnable" ), "MyThread %d" % count )
t.start()

# other Java way
from java.lang import Thread
class GreetThread( Thread ):
    def __init__( self, name, count ):
        Thread.__init__( self, "MyThread %d" % count )
        self._name = name  # Thread has a 'name' attribute
    def run( self ):
        greet( self._name )
count += 1        
t = GreetThread( "Thread subclass", count )
t.start()

*whew*

BTW, the thread naming stuff is good practice but not required.

kb