I noticed the number of enwiki master connections was higher according to tendril.wm.org that before. I see in the logs:
2015-06-22 10:28:17 mw1171 frwiki DBPerformance INFO: [GET] Expectation (masterConns <= 0) by MediaWiki::main not met:
[connect to 10.64.16.12 (frwiki)]
TransactionProfiler.php line 307 calls wfBacktrace()
TransactionProfiler.php line 146 calls TransactionProfiler->reportExpectationViolated()
LoadBalancer.php line 550 calls TransactionProfiler->recordConnection()
ConsistentReadConnectionManager.php line 92 calls LoadBalancer->getConnection()
ConsistentReadConnectionManager.php line 117 calls Wikibase\Client\Store\Sql\ConsistentReadConnectionManager->getWriteConnection()
SqlUsageTracker.php line 131 calls Wikibase\Client\Store\Sql\ConsistentReadConnectionManager->beginAtomicSection()
UsageUpdater.php line 81 calls Wikibase\Client\Usage\Sql\SqlUsageTracker->trackUsedEntities()
DataUpdateHookHandlers.php line 173 calls Wikibase\Client\Store\UsageUpdater->addUsagesForPage()
DataUpdateHookHandlers.php line 112 calls Wikibase\Client\Hooks\DataUpdateHookHandlers->doParserCacheSaveComplete()
Hooks.php line 204 calls Wikibase\Client\Hooks\DataUpdateHookHandlers::onParserCacheSaveComplete()
ParserCache.php line 280 calls Hooks::run()
PoolWorkArticleView.php line 151 calls ParserCache->save()
PoolCounterWork.php line 123 calls PoolWorkArticleView->doWork()
Article.php line 674 calls PoolCounterWork->execute()
ViewAction.php line 44 calls Article->view()
MediaWiki.php line 413 calls ViewAction->show()
MediaWiki.php line 291 calls MediaWiki->performAction()
MediaWiki.php line 634 calls MediaWiki->performRequest()
MediaWiki.php line 431 calls MediaWiki->main()
index.php line 41 calls MediaWiki->run()
index.php line 3 calls include()
This really should use queuing or something (which also avoids tying page views up with a SPOF).