I have data coupled with a Lock = boost::shared_mutex.
I am locking data access with
reader locks ReadLock = boost::shared_lock<Lock>
and writer locks WriteLock = boost::unique_lock<Lock>.
Obviously, lots of readers may be reading the data at a time, and only one writing at it. But here's the catch:
A single thread may have mutliple readlocks on the same mutex, because it's calling functions that are locking the data themselves (with a ReadLock). But, as I have found, this causes inter-locking:
- Thread 1 read-locks data (Lock1)
- Thread 2 waits with a write-lock (LockW)
- Thread 1 spawns another read-lock (Lock2) while Lock1 is still alive
Now I get a lock because Lock2 is waiting for LockW to exit, LockW is waiting for Lock1, andLock1 is stuck because of Lock2.
I don't know if it's possible to change the design so that each thread only does a single ReadLock. I believe that having a system that starves Writers would solve my issues. Is there a common way on how to handle my case?