IOS memory leak because of WWW object

htudrshtsrhtsthsht · 2014-10-21T16:33:00.000Z

Hi there,

I have a nifty memory leak when I run my project on the IOS platform. I have checked it using instruments leak tool and debug using Xcode 6. In some cases it looks like the WWW object is never disposed.

I°) Here is the part of code that handle sending WWW requests:

private void issueRequestWithoutQueuing(string url, Dictionary<string, string> parameters = null, Callback<ServerData> successCallback = null, Callback<string> apiFailureCallback = null, Callback<string> layerFailureCallback = null, bool showSpinner = false)
{
	QueuedWWWObject queueWWW = new QueuedWWWObject();
	queueWWW.url = url;
	queueWWW.successCB = successCallback;
	queueWWW.apiFailureCB = apiFailureCallback;
	queueWWW.layerFailureCB = layerFailureCallback;
	if (parameters != null)
	{
		queueWWW.parameters = parameters;
	}
	issueRequest(queueWWW, showSpinner);
}

	private void issueRequest(QueuedWWWObject queueWWW, bool showSpinner = false)
	{
		numberRequestInProgress ++;

		WWW www;
		if (queueWWW.parameters != null && queueWWW.parameters.Count != 0)
		{
			WWWForm form = new WWWForm();
			foreach (KeyValuePair<string, string> pair in queueWWW.parameters)
			{
				form.AddField(pair.Key, pair.Value);
			}
			www = new WWW(queueWWW.url, form);
		}
		else
		{
			www = new WWW(queueWWW.url);
		}

		NetworkManager.instance.StartCoroutine(WaitForRequest(www, queueWWW, queueWWW.successCB, queueWWW.apiFailureCB, queueWWW.layerFailureCB));
	}

We are waiting for request until we receive either that the request is done, there has been an error, or the request has timed out

	private IEnumerator<WWW> WaitForRequest(WWW www, Callback<ServerData> successCallback = null, Callback<string> apiFailureCallback = null, Callback<string> layerFailureCallback = null)
	{
		
		int startLaunchRequestTime = ServerTime.instance.getRealGameTime();
		while (!www.isDone && www.error == null && ((ServerTime.instance.getRealGameTime() - startLaunchRequestTime) < REQUEST_TIMEOUT))
		{
			yield return www;
		}
		
		LaunchCallback cb = new LaunchCallback();
		cb.www = www;
		cb.successCB = successCallback;
		cb.apiFailureCB = apiFailureCallback;
		cb.layerFailureCB = layerFailureCallback;
		
		if ((ServerTime.instance.getRealGameTime() - startLaunchRequestTime) >= REQUEST_TIMEOUT)
		{
			cb.timeOutError = true;
		}
		
		_launchCallbacks.Add(cb);
	}

II°) And then, in the update function, where we request the results for the launchcallback, handle the callbacks, and dispose the WWW object:

	public void update()
	{
		int len = _launchCallbacks.Count;
		List<LaunchCallback> callbackToDelete = new List<LaunchCallback>();
		for (int i=0; i<len; i++)
		{
			LaunchCallback cb = _launchCallbacks*;*

 	RequestResult(cb.www, cb.hasTransaction,  cb.successCB, cb.apiFailureCB, cb.layerFailureCB, cb.timeOutError);*

```
 	callbackToDelete.Add(cb);*
```
```
 }*
```

 foreach(LaunchCallback call in callbackToDelete)*

```
 {*
```
```
 	_launchCallbacks.Remove(call);*
```
```
 	call.dispose();*
```
```
 }*
```
}*
private void RequestResult(WWW www, bool hasTransaction, Callback successCallback, Callback apiFailureCallback , Callback layerFailureCallback, bool timeOutError)*
{*

 // handles success/ failure callbacks, not relevant here*

```
 numberRequestInProgress --;*
```
}*
-------------------------------------------------------------------
III°) The LauncCcallback class is just a container for the WWW object and its callbacks:
public class LaunchCallback
{
public Callback successCB;*
public Callback apiFailureCB;*
public Callback layerFailureCB;*
public WWW www;*
public bool hasTransaction;*
public bool timeOutError = false;*
public void dispose()*
{*

 Debug.Log (" DISPOSING WWW object " + www.url );*

```
 www.Dispose();*
```
```
 successCB = null;*
```
```
 apiFailureCB = null;*
```
```
 layerFailureCB = null;*
```
}*
}

-------------------------------------------------------------------
When I run the project on IOS, I get the debug output of DISPOSING WWW object " + www.url, but the leak instrument tells me that the issueRequest function has leaked several strings, dictionary etc etc, as if the WWW has not been disposed:
Imgur: The magic of the Internet
When I put a breakpoint in Xcode, we pass in the destroy function for every request:
extern “C” void UnityDestroyWWWConnection(void* connection)
{
_ UnityWWWConnectionDelegate* delegate = (UnityWWWConnectionDelegate*)connection;_

[delegate cleanup];*
[delegate release];*
}
which calls this:
- (void)cleanup
{
[_connection cancel];*
_connection = nil;*
[_data release];*
data = nil;*
}
I really don’t know what’s going on, because I do pass in the dispose function of the launchcallback. Is there any references that could lead the WWW object to not be disposed?
PS: I am using unity 4.5.5 & monodevelop 4.0.1
Many thanks,
Down
-------------------------------------------------------------------------------------------------------------------
UPDATE 1:
A little update:
After reviewing the code generated by unity in xcode and analyzing it: xcode tells me that there is a potential leak in the WWWConnection.mm, particulary here, the delegate.connection is never cleaned:
extern “C” void* UnityStartWWWConnectionGet(void* udata, const void* headerDict, const char* url)
{
_ UnityWWWConnectionDelegate* delegate = [UnityWWWConnectionDelegate newDelegateWithCStringURL:url udata:udata];

_ NSMutableURLRequest* request =_
_ [UnityWWWConnectionDelegate newRequestForHTTPMethod:@“GET” url:delegate.url headers:(NSDictionary*)headerDict];_

delegate.connection = [NSURLConnection connectionWithRequest:request delegate:delegate];*
return delegate;*
}
the same occurs for POST methods:
extern “C” void* UnityStartWWWConnectionPost(void* udata, const void* headerDict, const char* url, const void* data, unsigned length)
{
_ UnityWWWConnectionDelegate* delegate = [UnityWWWConnectionDelegate newDelegateWithCStringURL:url udata:udata];_

_ NSMutableURLRequest* request =_
_ [UnityWWWConnectionDelegate newRequestForHTTPMethod:@“POST” url:delegate.url headers:(NSDictionary*)headerDict];_

[request setHTTPBody:[NSData dataWithBytes:data length:length]];*
[request setValue:[NSString stringWithFormat:@“%d”, length] forHTTPHeaderField:@“Content-Length”];*
delegate.connection = [NSURLConnection connectionWithRequest:request delegate:delegate];*
return delegate;*
}
Which correlates nicely with what I see:
Imgur: The magic of the Internet
I don’t really know what to do, as it looks like its related to the unity code. Any help would be appreciated.
------------------------------------------------------------------------------------------------------------------------------------------
UPDATE 2
I have a similar leak when I call this function:
private void OnEnable()*
{*

 StartCoroutine(doGet(facebookURL, onGetFacebookAvatar));*

}*
public IEnumerator doGet(string url, Callback callback = null)*
{*
```
 using (WWW www = new WWW(url))*
```
```
 {*
```
```
 	yield return www;*
```
```
 	if (callback != null)*
```
```
 	{*
```
```
 		callback(www);*
```
```
 		callback = null;*
```
```
 	}*
```
```
 }*
```
}*
private void onGetFacebookAvatar(WWW result)*
{*

 if (!string.IsNullOrEmpty (result.error))*

```
 {*
```

 	ErrorManager.instance.logWarning (ErrorManager.ERROR_FACEBOOK_API,  "Get facebook avatar failed : " + result.error, "AvatarBehaviour");*

```
 }*
```
```
 else*
```
```
 {*
```

 	Texture2D texture = new Texture2D(frame.width-20, frame.height-20);*

 	if (!_facebookAvatar.ContainsKey(_userID))*

```
 	{*
```

 		// Never use www.texture as it cause memory leak (WWW object is never released)*

 		result.LoadImageIntoTexture(texture);*

 		_facebookAvatar.Add(_userID, texture);*

```
 	}*
```

 	avatarTexture.mainTexture = texture;*

 	avatarTexture.width = frame.width - 20;*

 	avatarTexture.height = frame.height - 20;*

 	NGUITools.SetActiveSelf(avatarSprite.gameObject, false);*

 	NGUITools.SetActiveSelf(avatarTexture.gameObject, true);*

```
 }*
```
}*
see Imgur: The magic of the Internet
---------------------------------------------------------------------------------------------------------------
UPDATE 3:
After some investigation, adding the line:
[request release];
here

extern “C” void* UnityStartWWWConnectionGet(void* udata, const void* headerDict, const char* url)
{
_ UnityWWWConnectionDelegate* delegate = [UnityWWWConnectionDelegate newDelegateWithCStringURL:url udata:udata];_

_ NSMutableURLRequest* request =_
_ [UnityWWWConnectionDelegate newRequestForHTTPMethod:@“GET” url:delegate.url headers:(NSDictionary*)headerDict];_

delegate.connection = [NSURLConnection connectionWithRequest:request delegate:delegate];*
[request release];
return delegate;*
}

Does helps, but still some leak, maybe because what’s inside the request is not fully released (string and stuff), still investigating

htudrshtsrhtsthsht · 2014-10-27T08:40:52.000Z

All right, it seems that I was not alone:

issuetracker.unity3d.com

Unity IssueTracker - Memory leak in WWW class on iOS

CFURLRequest, a NSMutableURLRequest and a NSURLRequestInternal objects are not released from memory in the cleanup function. After i...

Looks like it’s solved in unity 4.5.6, just have to wait for the release. Anyway, thx for the help