Wireless n-networks in Ubuntu 13.04 and WICD

Question

every time i make a request to my web server via NSURLSession/Connection it leaks! To be honest it is not much but if you have to make a couple hundreds or thousands of calls this gets nasty.

I have been on this for about a week now. I have tried everything. NO cache , little cache, setting everything on nil after the call is done(which is unnecessary), using datatask for sessions or just connection with requests. Every time i get a little more memory allocated and i have not found a way to solve this problem.

So i set up a little testApp:

#import "ViewController.h"

@interface ViewController ()
@property NSString *param;
@property NSURL * url;
@property NSURLConnection *test;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];



    self.param = [NSString stringWithFormat:@"hi"];
    self.url = [[NSURL         alloc]initWithString:@"http://127.0.0.1/xmlfile.php"];
    for (int i = 0; i<20000; i++){
        [self connect:self.param url:self.url];
    }
    NSLog(@"I AM DONE!");
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any   resources that can be recreated.
}


- (NSData *)connect:(NSString*)param url:(NSURL*)url{
    self.test = [[NSURLConnection alloc]initWithRequest:nil  delegate:self];
    [[NSURLCache sharedURLCache] removeAllCachedResponses];
       return nil;
}

@end

i would love to add images of the memory usage but i am too new. so just go here: 5k:iterations http://i59.tinypic.com/123tts2.png 20k: http://i59.tinypic.com/1zzqsrk.png

I have heard that this could be a problem with ios8.

Please help!

I am open for everything and would be happy if someone could prove me wrong and show me the right way. Thanks a bunch

Solution

Please verify that your driver is iwlwifi.

lsmod | grep iwl

If you wish to disable N speeds in order to connect seamlessly, add to one file:

gksudo gedit /etc/modprobe.d/iwlwifi.conf

At the end of the file, add a new line:

options iwlwifi 11n_disable=1

Proofread, save and close gedit. After a reboot, you should be all set. If you are able to connect to home and work networks without any issues, this is not necessary.

Comments

[chili555]

It's a bug: bugs.launchpad.net/ubuntu/+source/wicd/+bug/1132529 I doubt Wicd will enable you to connect to an N network any easier than Network Manager. Intel products with the iwlwifi driver are indeed tricky. Does your employer also have G available? If you disable N can you connect to G? sudo modprobe -r iwldvm; sudo modprobe -r iwlwifi; sudo modprobe iwlwifi 11n_disable=1

[vlp-1]

@chili555: Thanks. I have no trouble connecting to G the way it is now, it's just that I was told that N is more stable, and therefore wanted to make that work. So if wicd does not help me with that, I guess I don't need it. Do you know if my problem is due to a bug in the iwlwifi driver then? And if there is any fix/alternative?

[chili555]

That is a matter of debate. Some card/iwlwifi driver/router combinations, including mine, have no trouble whatever with N speeds. Others are just impossible. Since this is your employers network, you can probably not log on to the settings page of the router and fiddle with settings until it works. Frankly, I find N no more or less stable, but that may be due to the fact that are very few other networks in range at my home. If it were me, I'd disable N permanently, remove Wicd and be done. If you need guidance, post back.

[vlp-1]

Ok I will do that. However, when I run the second or third command that you gave, I get the error:Error: missing module name. FATAL: Error running remove command for iwlwifi

[chili555]

Please try: lsmod | grep iwl. In 13.04, the iwldvm or iwlmvm module needs to be unloaded first. Remove whatever you found. If not iwldvm, then do: sudo modprobe -r iwlmvm; sudo modprobe -r iwlwifi; sudo modprobe iwlwifi 11n_disable=1. If you then connect, we can write a conf file to make it permanent.

[vlp-1]

Hm it keeps telling me that the module name is missing, or that the module is not found. If it doesn't hurt to just leave the settings as they are, I think I will just do that? Anyway, thank you for your help. If you make it an answer, I will accept it.

[Snuu]

Sadly not changing a thing. Thats actually the way i implemented it in the app i was working on before i encountered this problem. Please try it for yourself

[Matt Gibson]

I tried it for myself before I posted. I ran your original code, and saw constantly-rising memory use peaking at around 8GB in the simulator. I ran it with my changes and it flattened out at around 700MB. The only other difference with my code is that I'm grabbing simple default html page at http://localhost/ rather than the http://127.0.0.1/xmlfile.php that I obviously don't have. Is it possible that your PHP file isn't returning properly, or something?

[Matt Gibson]

Incidentally, after it flattens out at around 700MB, the responses do start coming in, and gradually the memory usage falls as all 20,000 responses are processed. You do realise that you're virtually simultaneously queueing 20,000 asynchronous connections, and that your device might be somewhat overwhelmed by that, right? In the simulator it carries on like a trouper and several minutes later it manages to get through all 20,000. I'm guessing there's protection in the stack to stop you hitting a server too hard.