Re: Tomcat JDBC CP: Exponential backoff?
Thomas, On 1/26/23 03:00, Thomas Meyer wrote: Am 18. Januar 2023 23:20:29 MEZ schrieb Christopher Schultz : Thomas, On 1/17/23 13:33, Thomas Meyer wrote: Does Tomcat's CP support exponential backoff in case DB is unavailable for some reason? I didn't find anything in the documentation in this regards. I don't think is supports any such thing. What would be the purpose of exponential back-off... don't you want to connect ASAP? Hi, Not really sure, but I think the idea is to protect the database from getting overloaded with requests once it's coming up again. Sadly the description given in https://cloud.google.com/sql/docs/postgres/manage-connections#backoff Is very vague and I think won't really help much to mitigate above problem, if any. I found this interesting article and test class that tries to demonstrate the resp. behavior of the situation: https://github.com/brettwooldridge/HikariCP/wiki/Bad-Behavior:-Handling-Database-Down https://github.com/brettwooldridge/HikariCP-benchmark/blob/master/src/test/java/com/zaxxer/hikari/benchmark/DbDownTest.java There seems also to be an reply to above benchmark from the vibur dbcp author, which has some interesting points: https://github.com/brettwooldridge/HikariCP/issues/230 While investigating the reason of why exponential backoff would make sense I also did stumble across this article: https://aws.amazon.com/de/blogs/architecture/exponential-backoff-and-jitter/ This article make much more sense in my head, I.e. use exponential backoff with jitter to protect the restarting database from getting "flooded". But HikariCP does only support plain exponential backoff and probably won't help much in above described situation, because once the database is starting to accept connections again, all HikariCP connections will probably align at the same time to start creating connections again. If you are worried abou tyour database being flooded with requests, you should limit the number of connections your database will accept /at the database/. If you have 10 applications connecting to the db each with their own connection pools, even exponential backoff won't help avoid all of them (separately!) flooding the database. -chris - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Tomcat JDBC CP: Exponential backoff?
Am 18. Januar 2023 23:20:29 MEZ schrieb Christopher Schultz : >Thomas, > >On 1/17/23 13:33, Thomas Meyer wrote: >> Does Tomcat's CP support exponential backoff in case DB is unavailable for >> some reason? >> I didn't find anything in the documentation in this regards. > >I don't think is supports any such thing. What would be the purpose of >exponential back-off... don't you want to connect ASAP? Hi, Not really sure, but I think the idea is to protect the database from getting overloaded with requests once it's coming up again. Sadly the description given in https://cloud.google.com/sql/docs/postgres/manage-connections#backoff Is very vague and I think won't really help much to mitigate above problem, if any. I found this interesting article and test class that tries to demonstrate the resp. behavior of the situation: https://github.com/brettwooldridge/HikariCP/wiki/Bad-Behavior:-Handling-Database-Down https://github.com/brettwooldridge/HikariCP-benchmark/blob/master/src/test/java/com/zaxxer/hikari/benchmark/DbDownTest.java There seems also to be an reply to above benchmark from the vibur dbcp author, which has some interesting points: https://github.com/brettwooldridge/HikariCP/issues/230 While investigating the reason of why exponential backoff would make sense I also did stumble across this article: https://aws.amazon.com/de/blogs/architecture/exponential-backoff-and-jitter/ This article make much more sense in my head, I.e. use exponential backoff with jitter to protect the restarting database from getting "flooded". But HikariCP does only support plain exponential backoff and probably won't help much in above described situation, because once the database is starting to accept connections again, all HikariCP connections will probably align at the same time to start creating connections again. > >-chris > >- >To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >For additional commands, e-mail: users-h...@tomcat.apache.org > -- Diese Nachricht wurde von meinem Android-Gerät mit K-9 Mail gesendet. - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Tomcat JDBC CP: Exponential backoff?
Thomas, On 1/17/23 13:33, Thomas Meyer wrote: Does Tomcat's CP support exponential backoff in case DB is unavailable for some reason? I didn't find anything in the documentation in this regards. I don't think is supports any such thing. What would be the purpose of exponential back-off... don't you want to connect ASAP? -chris - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
