Re: [Pyobjc-dev] Possible memory leak passing Cocoa NSData or NSDictionary instances from python plugin to Objective-C (non-GC) code?

[Ronald O. <ron...@ma...>]

Barry,

Could you please file a bug for this on SourceForge when you don't  
find a solution? I don't think I'll be able to look into this this  
week and will be traveling after that.

Ronald

On 2 Jun, 2008, at 3:57, Barry Wark wrote:

> Hi all,
>
> I have an Objective-C application that uses plugins to generate some
> data. THe app is compiled against the 10.5 SDK and is running on
> Leopard (with the system python and pyobjc). The data is returned as
> NSData* instances and its parameters as an NSDictionary instance, as
> defined by the app's plugin formal protocol. Some of our plugins are
> written in Objective-C and some in Python ("compiled" with py2app).
> The app is compiled against the 10.5 SDK and is running on Leopard
> (with the system python and pyobjc).  I've noticed that there's a
> signficant apparent memory leak in the application when using
> Python-based plugins, but not when using the Objective-C based
> plugins. Therefore, I've concluded that the issue is with the plugins,
> not the main application. I've written a small demo app that exhibits
> the apparent leak behavior.
>
> The relevant sections of the Objective-C side are:
> - (IBAction)getDataFromPython:(id)sender {
>    id<TestProtocol> plugin = [[pluginClass alloc ] init];
>    NSAssert([plugin conformsToProtocol:@protocol(TestProtocol)],
>             @"Plugin not id<TestProtocol>.");
>
>    for(NSUInteger i=0; i<self.nReps; i++) {
>        NSData *d = [plugin getNumpyData];
>    }
>
>    [plugin release];
> }
>
> - (IBAction)getDictFromPython:(id)sender {
>    id<TestProtocol> plugin = [[pluginClass alloc ] init];
>    NSAssert([plugin conformsToProtocol:@protocol(TestProtocol)],
>             @"Plugin not id<TestProtocol>.");
>
>
>    for(NSUInteger i=0; i<self.nReps; i++) {
>        NSDictionary *d = [plugin getDictionary];
>    }
>
>    [plugin release];
> }
>
> and the corresponding "getNumpyData" and "getDictFromPython" methods
> in the plugin are:
>
>    import numpy as np
>
>    def getNumpyData(self):
>        return np.zeros(10000)
>
>    def getDictionary(self):
>        return NSDictionary.dictionaryWithObjectsAndKeys_('abc',
>                                        'string',
>                                        pkl.dumps(np.zeros(1000)),
>                                        'pkl_string',
>                                        None)
>
>
> Investigation with ObjectAlloc in Instruments suggests that the
> instances of "GeneralBlock" in the first case (getNumpyData) and
> "GeneralBlock" and CFDictionary in the second (getDictionary) case are
> created but not released, even after the event loop (and associated
> NSAutoreleasePool.drain) are completed.
>
> Is it possible that this is a memory leak caused by improper reference
> management across the Objective-C/python bridge?
>
> I am happy to file a bug in Apple's radar or the pyobjc sourceforge
> project, but I'm not sure 1) if this is a bug or my fault and 2) where
> the bug is most useful...
>
> Would anyone be able to help me?
>
> I've made a zip file with the Xcode project (app and plugin). The
> project folder also contains an Instruments file that will drive and
> record the behavior I describe above. The zip file is available from
> http://rieke-server.physiol.washington.edu/~barry/python/ 
> PyObjCTest.zip
>
> Any help would be greatly appreciated!
>
> Thanks!
>
> Barry
>
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