A quick Google search returns many results for fixing this error, but from what I can tell none of them give advice on how to discover the root cause. My understanding is that it happens whenever my application reaches a limit on the number of consecutive failures when connecting to the database. However, I can't figure out a way to determine the source of these failures. Is there a way to list the failed queries or connection attempts that led to this error? Ideally I would be able to determine whether this was due to a simple network failure, bad inputs, etc.
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How much RAM? Please provide `SHOW VARIABLES;` and `SHOW GLOBAL STATUS;`. There may be additional clues from the _type_ of connection error(s). – Rick James Dec 09 '19 at 19:05
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@RickJames I'll try that, thank you. This isn't my app and I'll need to request permission for devops to execute those commands. – Dan Mandel Dec 10 '19 at 14:19
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Maybe the app keep on opening new connections? We ever experienced that some of our in-house testing apps keeps on opening new connection to our test MySQL server. – FanoFN Dec 13 '19 at 07:14
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For every possible root cause, a dedicated column in table performance_schema.host_cache
will show how many time each root cause was found.
To investigate, simply execute:
SELECT * FROM performance_schema.host_cache
See the manual: https://dev.mysql.com/doc/mysql-perfschema-excerpt/8.0/en/host-cache-table.html

Marc Alff
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