Blair Zajac <bl...@orcaware.com> writes: > On 1/27/11 1:35 AM, Philip Martin wrote: >> Philip Martin<philip.mar...@wandisco.com> writes: >> >>> It appears that the kernel deadlock detection sometimes produces false >>> positives >> >> I believe I was mistaken when I assumed that fcntl() would block just >> the thread making the call; rereading the man page I think it is the >> whole process that blocks. That means this is not a false positive. > > I believe your first inclination was correct, that fcntl() just blocks > the calling thread. How could one system call block other threads > from doing work?
I'm not sure. The kernel knows which threads are part of the process so it could block them all. > I'm guessing the kernel doesn't look if the process is multithreaded > and if its making progress, it just assumes it is single threaded, > which is why it has to return EDEADLK. A little experimenting on my Linux box shows that when one thread of svnserve is blocked in fcntl() during a commit other threads still respond. So this probably does count as a false positive deadlock. -- Philip
