Dear Scott, Gary and all,
I appreciate so much for your replies! I am not a good C programmer. So I
made some mistakes in the code. C is used only when programming with BSD
sockets.
According to your suggestions, the code is changed as follows. But the leaks
are still notified by Instruments. But in Activity Monitor, the program
works fine. I feel weird about that. Could you figure out the problem?
Thanks!
Best regards,
Bing
- (void) run
{
char buffer[1025];
ssize_t numberBytesReceived;
while (true)
{
NSAutoreleasePool *loopPool = [[NSAutoreleasePool alloc]
init];
numberBytesReceived = recv(clientSocket, buffer, 1024, 0);
if (numberBytesReceived > 0)
{
buffer[numberBytesReceived] = '\0';
NSAutoreleasePool *subLoopPool = [[NSAutoreleasePool
alloc] init];
// This line sometimes gets huge leaks (about
167.80MB, 226933 leaks). But it does not always happen
// I don't understand why it gets leaked!
NSMutableString *receivedMessage =
[[[NSMutableString alloc] initWithBytes:buffer length:numberBytesReceived
encoding:NSUTF8StringEncoding] autorelease];
[self notifyMessageReceived:receivedMessage];
[subLoopPool drain];
}
else
{
[loopPool drain];
break;
}
[loopPool drain];
}
}
On Thu, Jun 16, 2011 at 12:21 AM, Scott Ribe <scott_r...@elevated-dev.com>wrote:
>
> On Jun 15, 2011, at 10:02 AM, Bing Li wrote:
>
> > char buffer[1024];
> > ssize_t numberBytesReceived;
> > while (true)
> > {
> > NSAutoreleasePool *loopPool = [[NSAutoreleasePool alloc]
> > init];
> > numberBytesReceived = recv(clientSocket, buffer, 1024, 0);
> > if (numberBytesReceived > 0)
> > {
> > buffer[numberBytesReceived] = '\0';
>
> So, if you receive 1024 bytes, you write past the end of the buffer. Now
> granted, you're only writing a 0 onto the least significant (assuming Intel)
> byte of numberBytesReceived, so it's not the source of your leak, but it's a
> pretty bad bug that's going to mess up your buffer contents for any buffer
> that's not a multiple of 256 bytes in length.
>
> > for (int i = 0; i < 1024; i ++)
> > {
> > buffer[i] = '\0';
> > }
>
> That's pretty pointless isn't it?
>
> > if (buffer[0] != '\0')
> > {
> > free(buffer);
> > }
>
>
> Seriously??? Freeing a stack buffer? Ouch. And the test? Why would you
> decide whether to free the block based on its contents?
>
> I don't see offhand anything in this method that would cause a leak. But if
> this code is typical of the rest of the program, then you have bugs all over
> the place that corrupt memory which can lead to all sorts of things
> failing--including memory reclamation.
>
> --
> Scott Ribe
> scott_r...@elevated-dev.com
> http://www.elevated-dev.com/
> (303) 722-0567 voice
>
>
>
>
>
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