Re: NSLog fixes output, but why?
Re: NSLog fixes output, but why?
- Subject: Re: NSLog fixes output, but why?
- From: Chris Idou <email@hidden>
- Date: Wed, 18 Mar 2009 15:50:33 -0700 (PDT)
Should we assume you have eliminated the obvious, that the arguments to NSLog don't have any method calls with side effects?
Or are there multiple threads whose timing could be changed by the logging?
________________________________
From: James Maxwell <email@hidden>
To: Cocoa Dev <email@hidden>
Sent: Thursday, 19 March, 2009 9:05:31 AM
Subject: NSLog fixes output, but why?
I've got a really frustrating, and really silly problem.
I have some fairly complex machine learning code I'm working on. I've noticed inconsistent output from a particular method. I'm doing some fairly nasty array and matrix stuff, which is all done in C, and I pass the arrays around wrapped in NSData objects. What's really strange is that, in this particular method, if I place an NSLog after calling and unwrapping a particular 2D matrix, then the output is as expected. If I remove the NSLog, the output is incorrect (or at least, unexpected). The system is pretty complex, and involves 4 different classes, so I won't post it here, and obviously I don't expect any magical help. But does anybody have any experience with something this flaky? Whereby literally adding a single NSLog (and thus obviously slowing things down a fair bit) makes the method run correctly?... It's just bizarre, to me.
Maybe somebody here has worked their way into a similar corner? Obviously I've done something stupid somewhere, but I don't really know how to go about finding it. It was weird enough to realize that the NSLog could make or break my output - tracking down the actual reason why is just baffling... Everything being done in these classes is basically procedural stuff, so it doesn't seem like timing should dramatically influence the output. But I am doing *lots* of iterations over this data. Does that suggest anything?
Any thoughts very much appreciated.
cheers,
J.
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