Bug #118329 Contribution: Optimize BigDecimal zero value handling to reduce memory foot ...

• Submitted: 2 Jun 12:32
• Modified: 19 Oct 16:28
• Reporter: OCA Admin (OCA)
• Status: Closed
• Category: Connector / J
• Severity: S3 (Non-critical)
• Version: 9.x
• OS: Any
• CPU Architecture: Any
• Tags: Contribution

[2 Jun 12:32] OCA Admin

Description:
This bug tracks a contribution by chengjun huang (Github user: SubtleSpark), as described in http://github.com/mysql/mysql-connector-j/pull/117

How to repeat:
See description

Suggested fix:
See contribution code attached

[2 Jun 12:32] OCA Admin

Contribution submitted via Github - Optimize BigDecimal zero value handling to reduce memory footprint 
(*) Contribution by chengjun huang (Github SubtleSpark, mysql-connector-j/pull/117#issuecomment-2925303388): I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.

Contribution: git_patch_2556548079.txt (text/plain), 2.26 KiB.

[2 Jun 12:47] MySQL Verification Team

Hello chengjun huang,

Thank you for the report and contribution.

regards,
Umesh

[3 Jul 15:49] Filipe Silva

Hi Chengjun Huang,

Can you please elaborate on this patch? Your assumption that Connector/J creates a new BigDecimal instance for each zero value seems to be wrong.

Actually, the test code you added into BigDecimalValueFactoryTest#testCreateFromBigDecimal doesn't fail without the remaining of your patch.

Please clarify.

[25 Jul 13:36] chengjun huang

I'm sorry for submitting the wrong test case.
Below is the correct test case. Please use it to replace the one I submitted in com.mysql.cj.result.BigDecimalValueFactoryTest.testCreateFromBigDecimal()

```code
assertSame(this.vf.createFromBigDecimal(new BigDecimal("0.0")), this.vf.createFromBigDecimal(new BigDecimal("0.0")));
assertNotSame(this.vf.createFromBigDecimal(new BigDecimal("0.0")), this.vf.createFromBigDecimal(new BigDecimal("0")));
```

[25 Jul 18:08] Filipe Silva

Thank you. It makes sense now.

[19 Oct 16:28] Edward Gilmore

Posted by developer:
 
Added the following note to the Connector/J 9.5.0 release notes:

When fetching zero values as BigDecimal, MySQL Connector/J created 
new instances unnecessarily, increasing memory usage. 
As of this release, internally cached BigDecimal zero values (with appropriate
scale) are reused wherever possible, reducing memory overhead.
      
Our thanks to Chengjun Huang for the contribution.