addBatch method cause Java heap memory char array grows too fast

[wangbing505]

The scenario involves a large number of calls to the addBatch method, Then use jmap to view heap memory，has lots of char[],although they are all unreachable objects that can be GC dropped.But it will lead to frequent GC and high CPU usage. How to solve it

[chernser]

Hi @wangbing505

• What is the ClickHouse jdbc version do you use?
• Is it a requirement to use JDBC?

[wangbing505]

Hi @chernser

1. ClickHouse jdbc version is 0.2.6，Can a higher version solve this problem？
2. yes，or Is there any other way to write data to clickhouse ?

[chernser]

@wangbing505

1. Yes, please, update to the latest 0.7.0 version. I do not see such code in it and everything should work fine.
2. Yes, you may use java client without JDBC - https://clickhouse.com/docs/en/integrations/java/client-v2

Please let me know how the update goes. Thanks!

[wangbing505]

@chernser Thank you for your answer，I will try using them and synchronize the results

[chernser]

@wangbing505 as the issue solved?

[wangbing505]

@chernser hello, I have been delayed by other things and will try it next week

[wangbing505]

@chernser Thank you, I tried it, Char [] has decreased，But there are other memory uses as well，maybe it's not a problem with the client anymore

[chernser]

Need to verify how jdbc-v2 handles it.

[chernser]

We might need to stream big SQL requests like we do with text formats. Will prioritize this work.