On Jul 13, 2012, at 7:46 PM, Rick Mann <rm...@latencyzero.com> wrote:
> I'm using NSFileHandle in an ARC app on OS X Lion to read from a serial port. > > Everything works fine 'till I go to close the port. I open the port with > POSIX calls, set up some stuff, then instantiate an NSFileHandle with the > file descriptor I got from open(). > > Then I call -readInBackgroundAndNotify, and a second file descriptor gets > opened (I see this by using lsof). > > That FD gets closed the moment some data comes in and a notification gets > posted, but I just go right back and call -readInBackgroundAndNotify again to > get the next data. > > The problem is when I go to close the port. I still have a pending > -readInBackgroundAndNotify, and so the port is opened twice. When I call > -closeFile on the NSFileHandle, it closes the FD I initially opened, but > leaves the second FD open. > > I tried setting the NSFileHandle reference to nil so that ARC would release > it, and hopefully call -dealloc on it, but either it's not doing that, or > -dealloc doesn't close that second FD either. > > In any case, when I go to open that port again, I get an error saying the > resource is busy (if I quit my app, all FDs get closed). > > This sure seems like a bug to me. Am I doing something wrong? NSFileHandle dups the file descriptor to avoid bugs where the descriptor is closed from under it. That's expected. NSFileHandle retains itself during the background operation to avoid being deallocated while it's still in progress. I think the -closeFile call is supposed to cancel the background operations which in turn should release that extra retain, but perhaps something in there is not working correctly. What does the Allocations instrument say about the retain/release history? If it looks like -readInBackgroundAndNotify is performing an extra retain that doesn't get released then you should file a bug report. -- Greg Parker gpar...@apple.com Runtime Wrangler _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
