IDs of task can duplicated when mvсс is on

Lines 70 to 73 in ea8449b

    
           function method.put(self, data, opts) 
        
               local max = self.space.index.task_id:max() 
        
               local id = max and max[1] + 1 or 0 
        
               local task = self.space:insert{id, state.READY, data}

To minimize the possibility of conflicts, MVCC uses what is called best-effort visibility: for write transactions it chooses read-committed, for read transactions it chooses read-confirmed.

by default task_id:max read confirmed , this is the key reason why duplicates occur in the case of an race condition

@R-omk

@R-omk Hi, do you have a reproducer?

I just reported an obvious problem that someone encountered in the telegram chat.

I think you should use require('txn_proxy') to reproduce issue without external client. (or net box client)

driver: fix duplicate id error with mvvc on

drivers: fix concurrency with mvcc

driver: fix duplicate id error with mvvc on put

driver: fix duplicate id error with mvvc on on take

driver: fix duplicate id error with mvvc on put and take

drivers: fix concurrency with mvcc

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IDs of task can duplicated when mvсс is on #207

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	function method.put(self, data, opts)
	local max = self.space.index.task_id:max()
	local id = max and max[1] + 1 or 0
	local task = self.space:insert{id, state.READY, data}

IDs of task can duplicated when mvсс is on #207

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better0fdead commented on Jun 22, 2023

R-omk commented on Jun 22, 2023

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