Bug #90518

Updated by Sybille Peters 9 months ago

 
 *Update*: My initial idea did not work out. I will investigate further ... 

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 Recently we are experiencing increasing number of exceptions and "too many connections" on TYPO3 9.5.13 in combination with DELETE queries on    cf_cache_rootline and cf_cache_rootline_tags that take excessively long.  

 Obviously, this is causing massive problems.  

 Findings: 

 * Increasing number of exceptions: An exception occurred while executing 'INSERT INTO `cf_cache_rootline ... Lock wait timeout exceeded; try restarting transaction | Doctrine\DBAL\Exception 

 This seems to be correlated with excessively long DELETE queries on cf_cache_rootline and cf_cache_rootline_tags with 2 JOINs. 

 <pre><code class="text"> 
 # Time: 200221 11:44:21 
 # User@Host: ------ @    [------] 
 # Thread_id: 13694456    Schema: -----    QC_hit: No 
 # Query_time: *2212.109482*    Lock_time: 0.000340    Rows_sent: 0    Rows_examined: *1007307838* 
 # Rows_affected: *94732* 
 SET timestamp=1582281861; 
 DELETE tags2, cache1 FROM cf_cache_rootline_tags AS tags1 JOIN cf_cache_rootline_tags AS tags2 ON tags1.identifier = tags2.identifier JOIN cf_cache_rootline AS cache1 ON tags1.identifier = cache1.identifier WHERE tags1.tag IN ('pageId_3'); 

 </code></pre> 


 (I blanked out some IP addresses etc.) 


 in Typo3DatabaseBackend::flushByTags() 










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