Dear Conrad, Jens, Tony, Scott, Wade and all,
I appreciate so much for your replies. I learn a lot from the interactions
with you. Since I am new, your patience is so valuable to me!
I just got the problem. At least, right now, there is no the leak. When
receiving messages, I put them into a queue. However, I forgot implementing
a dealloc for it and I also did not release it when the connection was
disconnected. After the bug was fixed, the leaking issue was solved.
But I still have a question. The queue is actually derived from NSArray. It
should be empty after when the connection was disconnected. Why was there
such a huge leak?
For the TCP issues, I planned to change my current solution. I will send the
length of the buffer first and then send the real data. I have ever done
that on .NET. The difference is that this time I need to exchange messages
among different OSs (Java/Linux and iOS). So XML is used. On .NET, I just
use its serialization technique. I am not sure if I need to consider little
endian/big endian issues? My iMac is an Intel CPU. I don't need to do that,
right? What about iPad/iPhone?
When implementing multi-threading, NSOperationQueue is used in my system. I
don't create threads explicitly unless in some specific cases, for example,
a streaming control thread pool.
The major reason I intend to use sockets is that I attempt to design a P2P
communication protocol when transmitting data over the Internet. I also did
that successfully on .NET. I think a controllable socket is more flexible
although its programming is difficult a little bit.
I will learn Cocoa programming continually and carefully. Thanks so much for
your help again!
Best regards,
Bing
On Thu, Jun 16, 2011 at 4:10 AM, Conrad Shultz <
con...@synthetiqsolutions.com> wrote:
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> On 6/15/11 12:50 PM, Bing Li wrote:
> > Jens,
> >
> > Thanks so much for your suggestions!
> >
> > I wonder why it works fine according to Activity Monitor if such a huge
> leak
> > exists. The consumed memory in the Activity Monitor is stable and much
> > smaller unless some threads are created at a high concurrent moment.
> After
> > the threads are dead, the consumed memory becomes stable and small. I
> feel
> > weird for this.
>
> Honestly, I feel like you are not listening to the excellent responses
> people are giving you.
>
> 1) Activity Monitor is not a profiling tool. Don't use it as such. Use
> Leaks/Allocations, maybe with some heapshot analysis thrown in as I
> believe I mentioned a while back.
>
> 2) Analyze your code with the Clang static analyzer ("Build & Analyze").
> This will shake out many common memory issues (and more).
>
> 3) Recognize that posting snippets of the code that you THINK might be
> responsible for a leak does not mean that people on the list can
> actually help you find it. For example, even if you are doing
> everything completely properly inside a function, if that function
> returns some object, the calling code can still leak that object.
>
> 4) It seems as if much of your code is multi-threaded. All else being
> equal, this makes such problems even harder to debug. If I were having
> such serious issues, I would probably spend some time trying to get the
> task to work on the main thread and only once that is thoroughly
> debugged would I break it up across threads. (This won't work for every
> type of problem, but if it can work for you, I'd do it.)
>
> 5) As others have commented, there is substantial evidence that your
> code probably has issues other than memory management. If you are, for
> example, smashing the stack in your C code, all bets are off and you
> really need to fix that first.
>
> It's been so long since you first started posting that I've forgotten
> what you are trying to do. You are communicating in a high level format
> (XML), yet all your code seems to concern very low level network
> behaviors (opening sockets, reading bytes, et cetera). I wonder whether
> you are over-engineering all this. What is your goal?
>
> - --
> Conrad Shultz
>
> Synthetiq Solutions
> www.synthetiqsolutions.com
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