JAVA-893

[John Sanda]

I recently upgraded the version of the driver used in my application from 3.0.1 to 3.0.5. We have some performance tests that run on each pull request. The client in those tests pump writes as fast as they will be processed. After upgrading to 3.0.5, our performance tests started failing with BusyPoolExceptions. I should also point out that all of our queries are async. I increased the max queue size to 1024 as well as the max connections per host to see if it would fix our performance tests, but we still see the same errors. Is this just a case of needing to add throttling within my code? If so, how come I did not need it when using 3.0.1?

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- John

[Alexandre Dutra]

Hi,

JAVA-893 made the connection pool completely asynchronous, whereas previously, it would actually block until a connection is made available, that's why you did not need to throttle your code. Since the code now doesn't block anymore, you are probably saturating the driver to the point where it throws a BusyPoolException.

If you already tried playing with the queue size with no success, I guess your best next option is indeed to throttle your writing threads.

Thanks,

Alexandre

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Alexandre Dutra

Driver & Tools Engineer @ DataStax

[John Sanda]

I wanted to report back since I revisited this issue today. Setting max connections == core connections seems to resolve the problems I encountered.

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Alexandre Dutra

Driver & Tools Engineer @ DataStax

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- John