Problem 🐞
There is a possible scenario when using the graph.SimpleGraph structure that might lead to a deadlock!
Let me explain
SimpleGraph.Adj takes a mutex.RLock().- Under the hood,
SimpleGraph.Degree is called, which also takes mutex.RLock().
- If
mutex.Lock() is called between the 2 stages above (using SimpleGraph.AddEdge), then both functions get blocked forever.
A simple block of code demonstrates this issue (time.Sleep() is used to simulate the call order).
Solution ✅
- Create a sub function
SimpleGraph.degree() that doesn't use RLock() (similar to SimpleGraph.addVertex().
- Move code of
SimpleGraph.Degree() to the new function and leave only RLock() code.
code example with fix
Problem 🐞
There is a possible scenario when using the
graph.SimpleGraphstructure that might lead to a deadlock!Let me explain
SimpleGraph.Adjtakes a mutex.RLock().SimpleGraph.Degreeis called, which also takesmutex.RLock().mutex.Lock()is called between the 2 stages above (usingSimpleGraph.AddEdge), then both functions get blocked forever.A simple block of code demonstrates this issue (
time.Sleep()is used to simulate the call order).Solution ✅
SimpleGraph.degree()that doesn't useRLock()(similar toSimpleGraph.addVertex().SimpleGraph.Degree()to the new function and leave onlyRLock()code.code example with fix