MSR2016 - An Empirical Study on the Practice of Maintaining Object-Relational Mapping Code in Java...

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An Empirical Study on the Practice of Maintaining Object-Relational Mapping

Code in Java Systems

Mohamed Nasser, Parminder Flora

Tse-Hsun(Peter) Chen Ahmed E. HassanWeiyi Shang Jinqiu Yang Michael W. Godfrey

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Databases are essential in modern large-scale software systems

Database

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Object-Relational Mapping (ORM) eliminates the gap between objects and SQL

Database

• Less boilerplate code • Object-DB translations are done automatically

JavaClasses

Benefits over raw SQLs

ORM

Much less code and shorter development time

ORM provides another layer of abstraction

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ORM

Database mapping code@Table(name = “user”)

Performance configurationquery.cache()

ORM query codeUser u = q.getSingleResult();

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ORM is not a silver bullet

Using ORM comes with some hidden costs…

We have been working on helping developers improve ORM code for the past few years

Developers are often not aware of database access

Wow! I don’t need to worry

about DB code!

ORM code with performance anti-patterns

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Bad system performance

The performance impact can be SIGNIFICANT (ICSE 2014)!

ORM is hard to configure

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Hundreds of ORM performance-related

configuration

Un-optimal ORM configuration is common and causes significantly performance

problem (TSE 2016)!

Bad system Performance if

configured incorrectly

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

Studied Java systems

Large open-source e-commence system Enterprise system

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Portal Content management system

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

Lack of bug detection tool support for Java ORM

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Coverity PMD Google error-prone

Facebook InferFindBugs

More than 67% of Java developers use ORM, but there is limited tooling support (ICSE SEIP 2016)

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

No! There is limited tooling

support

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

No! There is limited tooling

support

ORM configurations are rarely tuned

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Most ORM code changes are related to ORM queries (35%) and ORM database mapping code (55%)

ORM performance configurations are rarely tuned (less than 10%)

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

No! There is limited tooling

support

No! ORM configurations

are rarely tuned

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

No! There is limited tooling

support

No! ORM configurations

are rarely tuned

ORM code changes are more scattered

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Such high change scatteredness may be caused by ORM’s inability to completely

abstract DB accesses

Studying maintenance activities of Java ORM code

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Expect: ORM-related changes are localized

Expect: Frequently tuning configurations

Expect: Tooling support due to ORM

popularity

No! There is limited tooling

support

No! ORM configurations

are rarely tuned

No! ORM code changes are

more scattered

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Tse-Hsun (Peter) Chen tsehsun@cs.queensu.ca