RedBlackTree runtime error: index out of range in .Values() func #174

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opened 2021-10-15 08:04:47 +00:00 by shojaeix · 1 comment

shojaeix commented

2021-10-15 08:04:47 +00:00

(Migrated from github.com)

I am using the RedBlackTree. Sometimes, when the application is under heavy traffic, this error shows up:

panic: runtime error: index out of range [2477] with length 2477

goroutine 83 [running]:
github.com/emirpasic/gods/trees/redblacktree.(*Tree).Values(0xc000004210, 0x2030099, 0x2030099, 0x20)
        C:/Users/Nitro-5/go/pkg/mod/github.com/emirpasic/[email protected]/trees/redblacktree/redblacktree.go:173 +0x10f

First, I thought maybe it's not thread-safe, So I started to use an RWmutex for the tree, but still facing the error.

Thanks for your help 🙏🏻

Hi I am using the RedBlackTree. Sometimes, when the application is under heavy traffic, this error shows up: ``` panic: runtime error: index out of range [2477] with length 2477 goroutine 83 [running]: github.com/emirpasic/gods/trees/redblacktree.(*Tree).Values(0xc000004210, 0x2030099, 0x2030099, 0x20) C:/Users/Nitro-5/go/pkg/mod/github.com/emirpasic/[email protected]/trees/redblacktree/redblacktree.go:173 +0x10f ``` First, I thought maybe it's not thread-safe, So I started to use an RWmutex for the tree, but still facing the error. Thanks for your help 🙏🏻

emirpasic commented

2021-10-15 09:48:01 +00:00

(Migrated from github.com)

@shojaeix

GoDS is not thread-safe (seeing this error, I am now having second thoughts make it all thread-safe), so protecting access to it is crucial with mutexes as you have done, otherwise, we could run into an undefined state.

The error occurs in the Values() function, so I guess that the tree is in an inconsistent state due to concurrent reads and writes. Try using a common mutex for both reading and writing on the tree, even when calling the Values() as something might be concurrently writing/deleting to the tree and the size of the tree in this function is not correct at that moment.

Let me know if this helps

@shojaeix GoDS is not thread-safe (seeing this error, I am now having second thoughts make it all thread-safe), so protecting access to it is crucial with mutexes as you have done, otherwise, we could run into an undefined state. The error occurs in the Values() function, so I guess that the tree is in an inconsistent state due to concurrent reads and writes. **Try using a common mutex for both reading and writing on the tree, even when calling the Values()** as something might be concurrently writing/deleting to the tree and the size of the tree in this function is not correct at that moment. Let me know if this helps