NSURLConnection優化

我試圖從iPhone瞭解3G網絡上的NSURLConnection性能。我有以下測試代碼NSURLConnection優化

-(void)doTest2 { 
    max = 5; 
    NSURL *url = [NSURL URLWithString:@"http://www.google.com"]; 
    NSURLRequest *request2 = [[[NSURLRequest alloc] initWithURL:url] autorelease]; 
    NSURLConnection *conn=[[NSURLConnection alloc] initWithRequest:request2 delegate:self]; 
    self.startDate = [NSDate date]; 
    if (conn) 
    { 
     receivedData = [[NSMutableData data] retain]; 
    } } 

- (void)connectionDidFinishLoading:(NSURLConnection *)connection { 
     self.endDate = [NSDate date]; 
     NSTimeInterval interval = [self.endDate  timeIntervalSinceDate:self.startDate]; 
     NSLog(@"Time:%f Size:%u", interval, [receivedData length]); 
     [receivedData release]; 

     count = count + 1; 
     if (count == max) { 
      count = 0; 
      sleep(3); 
     } 
     self.doTest2;}

第一個請求很慢（超過1秒）。請求2-5很快（小於.25秒）。如果我睡了3秒或更長時間，睡眠後的第一個請求很慢。但是如果我睡了不到3秒，速度很快。任何想法爲什麼？

來源

2010-08-21 Chris Miller