MySQL error warning: a long semaphore wait

Run before mysql When you're good , A series of warning：

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        InnoDB: Warning: a long semaphore wait
       
       

        
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Then there is an error ：

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        Error: semaphore wait has lasted > 600 seconds
       
       

        
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Then the service shuts down automatically , According to online information, it is because of the problem of hash adaptive index ,mysql Hash adaptive indexing is enabled by default , After indexing in this way , The efficiency of reading and writing can be improved 2 More than times , But there may be a deadlock problem , Online suggestion off

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        innodb_adaptive_hash_index
       
       

        
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The specific process ：

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        mysql -u root -t;
       
       

        
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        set global innodb_adaptive_hash_index=off;
       
       

        
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         View the modification results 
        
SHOW GLOBAL VARIABLES LIKE 'innodb_ada%';
       
       

        
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You can see innodb_adaptive_hash_index It's closed , complete .

Reference material ：

​ ​https://bugs.mysql.com/bug.php?id=50641​​

​ ​http://stackoverflow.com/questions/24860111/warning-a-long-semaphore-wait​​