Re: [Jython-users] memory leak

[Samuele P. <ped...@bl...>]

Hi.

If you're exec statements
repeatedely  create
new classes inheriting from java,
you could see memory leaks if you
don't set the described option.

You can check for that running your applet
under the appletviewer and passing
either -verbose:gc (jdk <1.3) or
-verbose:class (jdk >= 1.3) to the java
runtime with the -J option also
-J-verbose:gc or ....
And check whether the classes

org.python.pycode._pyx*
org.python.proxies.*

dynamically created during an exec 
are unloaded after a while. Under jdk 1.3
a System.gc triggers also class unloading
so you can add logic to the applet to
trigger System.gc() for you tests.
If they are not, setting the option should solve
the problem, so I would redo
the test with the option set to weak.

Weak could have a slightly performance
impact vs soft. On the other hand
for debugging the problem weak
is better, with weak gc force unloading, while
soft will cause unloading only in case
of low memory conditions. Only 
testing can tell you whether soft or weak
is the right setting for production code
wrt to performance. Anyway both
should not have any kind of big impact
unless your applet is very peculiar.

AFAIK this is the only potential
cause of leaks under Jython.
Let us know if 
you cannot solve your problem
or need further explanation.

regards, Samuele Pedroni.

----- Original Message ----- 
From: Sells, Fred <fr...@ad...>
To: <jyt...@li...>
Sent: Monday, December 17, 2001 3:38 PM
Subject: [Jython-users] memory leak


> I have a memory leak in an applet that uses the Python.exec() method
> multiple times.  I though that would work since I overwrite the same Python
> variable names with each invocation; however that is not the case.
> contonious calls end up in a VM out of memory error
> 
> the jython registry has the following entry.  Will this solve my problem
> (relating to memory leak :)  )?  Is there a difference between "soft" and
> "weak"?
> 
> # List of choices for internal tables impl (PyJavaClasses canonical map
> etc.),
> # these are separated through ':' and tryed from left to right.
> # For long running applications under java2, needing classes unloading,
> # in order to have jython runtime automatically discarding 
> # no longer needed info and avoding memory leakage, this can be set 
> # to weak or soft (=> an impl. using weak-refs or soft-refs will be used).
> #python.options.internalTablesImpl = soft
> #python.options.internalTablesImpl = weak
> 
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