I have an automated script that runs a test application over and over
again. It starts the app, opens the USB device, issues a few commands,
closes the USB device and then terminates the app then sleeps for a few
seconds. Then it repeats that over an over again. Around 10,000 to
15,000 iterations it hangs on this stack trunk:
I did a search in the archives and found the post below.
Any suggestions?
How do I avoid "a deadlock contending for that gate."
thanks!-
-lance
From: Florent Pillet <email@hidden>
Date: Fri, 14 May 2004 22:49:14 +0200
That's what I had been saying since a couple messages... That it is a
bug in IOUSBFamily, that is has been around for quite some Mac OS X
releases, and that it happens with a variety of USB devices. The
problem is always the same: a hang in USBInterfaceOpen when called from
userland code. I noticed it first while using Palm devices and Palm's
HotSync synchronization software, which itself is a userland
application. Later, with my own code, I started getting hangs too and
others are reporting the same problem, always with userland code.
Unfortunately this doesn't happen all the time, but I'll try to keep
USB Prober logging stuff at level 7. I'm running a dual G4 with a bunch
of USB devices connected, so that may not render debugging easy, but
since the USB hangs the end of the trace should be the deadlock
point...
On 14 mai 04, at 20:30, Barry Twycross wrote:
I didn't realise this wasn't one of our functions. I didn't look
closely enough at the trace to see "darwin.c" rather than IOUSB...
something as the file.
The problem is really with this line:
#3 0x000acce4 in IOUSBInterfaceClass::USBInterfaceOpen(bool) ()
The interface open is hanging. That's in our open source
IOUSBInterfaceUserClient.cpp, it gets to
IOUSBInterfaceUserClient::open(bool seize). That just does an open on
the underlaying interface. (IOUSBInterface.cpp).
There are lots of log messages in that function so running a logging
family and seeing what pops up should get you some pointers. That
function runs something on a command gate. So my guess is a deadlock
contending for that gate.
It doesn't look like this is a descriptor problem like I was
speculating about yesterday.
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