Context (CPU State) Switches

Shared memory access


Race conditions / data race
reordered instructions -> memory barriers / atomics
thread switch at any time -> locking / atomics

Deadlocks
2x lock
no unlock
nested locks

Lock contention
threads wait more than they work

Starvation
cannot acquire a lock


Locks
Spin lock (while loop)
Ticket lock (get number, wait for that)
read/write (shared read, exclusive write)
Condition Variables (wake threads up)

Pooling
Manager Thread (one thread idle, bad)
Job stealing (let threads steal from others)
Shared queue (threads acquire one job at a time)