High Performance Hibernate JavaZone 2016

High-Performance HibernateVLAD MIHALCEA

About me

• @Hibernate Developer

• vladmihalcea.com

• @vlad_mihalcea

• vladmihalcea

Agenda

• Performance and Scaling

• Connection providers

• Identifier generators

• Relationships

• Batching

• Fetching

• Caching

Performance Facts

“More than half of application performance bottlenecks originate in the database”

AppDynamics - http://www.appdynamics.com/database/

Google Ranking

“Like us, our users place a lot of value in speed — that's why we've decided to take site speed into account in our search

rankings.”

https://webmasters.googleblog.com/2010/04/using-site-speed-in-web-search-ranking.html

Performance and Revenue

“It has been reported that every 100ms of latency costs

Amazon 1% of profit.”

http://radar.oreilly.com/2008/08/radar-theme-web-ops.html

Response Time and Throughput

• n - number of completed transactions

• t - time interval

𝑇𝑎𝑣𝑔 =𝑡

𝑛=

1𝑠

100= 10 𝑚𝑠

𝑋 =𝑛

𝑡=

100

1𝑠= 100 𝑇𝑃𝑆

Response Time and Throughput

𝑋 =1

𝑇𝑎𝑣𝑔

“The lower the Response Time,

The higher the Throughput”

The anatomy of a database transaction

Response Time

• connection acquisition time

• statement submit time

• statement execution time

• result set fetching time

• idle time prior to releasing database connection

𝑇 = 𝑡𝑎𝑐𝑞 + 𝑡𝑟𝑒𝑞 + 𝑡𝑒𝑥𝑒𝑐 + 𝑡𝑟𝑒𝑠 + 𝑡𝑖𝑑𝑙𝑒

Agenda




• Relationships

• Batching

• Fetching

• Caching

Connection Management

Metric DB_A (ms) DB_B (ms) DB_C (ms) DB_D (ms) HikariCP (ms)

min 11.174 5.441 24.468 0.860 0.001230

max 129.400 26.110 74.634 74.313 1.014051

mean 13.829 6.477 28.910 1.590 0.003458

p99 20.432 9.944 54.952 3.022 0.010263


Connection Providers

DataSourceConnectionProvider

Connection Provisioning

FlexyPool

• concurrent connections

• concurrent connection requests

• connection acquisition time

• connection lease time histogram

• maximum pool size

• overflow pool size

• retries attempts

• total connection acquisition time

• Java EE

• Bitronix / Atomikos

• Apache DBCP / DBCP2

• C3P0

• BoneCP

• HikariCP

• Tomcat CP

• Vibur DBCP

https://github.com/vladmihalcea/flexy-pool

FlexyPool – Concurrent connection requests

1

28

55

82

10

9

13

6

16

3

19

0

21

7

24

4

27

1

29

8

32

5

35

2

37

9

40

6

43

3

46

0

48

7

51

4

54

1

56

8

59

5

62

2

64

9

67

6

70

3

73

0

75

7

78

4

81

1

83

8

86

5

89

2

91

9

94

6

97

3

10

00

10

27

0

2

4

6

8

10

12

Sample time (Index × 15s)

Co

nn

ecti

on

req

ues

ts

max mean p50 p95 p99

FlexyPool – Pool size growth

1

28

55

82

10

9

13

6

16

3

19

0

21

7

24

4

27

1

29

8

32

5

35

2

37

9

40

6

43

3

46

0

48

7

51

4

54

1

56

8

59

5

62

2

64

9

67

6

70

3

73

0

75

7

78

4

81

1

83

8

86

5

89

2

91

9

94

6

97

3

10

00

10

27

0

1

2

3

4

5

6


Max

po

ol s

ize


FlexyPool – Connection acquisition time

12

85

58

21

09

13

61

63

19

02

17

24

42

71

29

83

25

35

23

79

40

64

33

46

04

87

51

45

41

56

85

95

62

26

49

67

67

03

73

07

57

78

48

11

83

88

65

89

29

19

94

69

73

10

00

10

27

0

500

1000

1500

2000

2500

3000

3500


Co

nn

ecti

on

acq

uis

itio

n t

ime

(ms)


FlexyPool – Connection lease time

1

29

57

85

11

3

14

1

16

9

19

7

22

5

25

3

28

1

30

9

33

7

36

5

39

3

42

1

44

9

47

7

50

5

53

3

56

1

58

9

61

7

64

5

67

3

70

1

72

9

75

7

78

5

81

3

84

1

86

9

89

7

92

5

95

3

98

1

10

09

10

37

0

5000

10000

15000

20000

25000

30000

35000

40000


Co

nn

ecti

on

leas

e ti

me

(ms)


Agenda




• Relationships

• Batching

• Fetching

• Caching

JPA Identifier Generators


• IDENTITY

• SEQUENCE

• TABLE

• AUTO

IDENTITY

• In Hibernate, IDENTITY generator disables JDBC batch inserts

• MySQL 5.7 does not offer support for database SEQUENCE

SEQUENCE

• Oracle, PostgreSQL, and even SQL Server 2012

• May use roundtrip optimizers: hi/lo, pooled, pooled-lo

• By default, Hibernate 5 uses the enhanced sequence generators

<property name="hibernate.id.new_generator_mappings" value="true"/>

SEQUENCE - Pooled optimizer (50 rows)

1 5 10 50

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Sequence increment size

Tim

e (m

s)

TABLE

• Uses row-level locks and a separate transaction/connection

• May use roundtrip optimizers: hi/lo, pooled, pooled-lo

• By default, Hibernate 5 uses the enhanced sequence generators

<property name="hibernate.id.new_generator_mappings" value="true"/>

TABLE - Pooled optimizer (50 rows)

1 5 10 50

0

0.5

1

1.5

2

2.5

3

Table increment size

Tim

e (m

s)

IDENTITY vs TABLE (100 rows)

• IDENTITY makes no use of batch inserts

• TABLE generator using a pooled optimizer with an increment size of 100

IDENTITY vs TABLE (100 rows)

1 2 4 8 16

0

500

1000

1500

2000

2500

Thread count

Tim

e (m

s)

Identity Table

AUTO: IDENTITY vs TABLE?

• Prior to Hibernate 5, AUTO would resolve to IDENTITY if the database supports such a feature

• Hibernate 5 uses TABLE generator if the database does not support sequences

SEQUENCE vs TABLE (100 rows)

• Both benefiting from JDBC batch inserts

• Both using a pooled optimizer with an increment size of 100

SEQUENCE vs TABLE (100 rows)

1 2 4 8 16

0

200

400

600

800

1000

1200

Thread count

Tim

e (m

s)

Sequence Table

Agenda




• Relationships

• Batching

• Fetching

• Caching

Relationships


Agenda




• Relationships

• Batching

• Fetching

• Caching

Batching


• SessionFactory setting

• Session-level configuration since Hibernate 5.2

Batching - SessionFactory

<property name="hibernate.jdbc.batch_size" value="5"/>

• Switching from non-batching to batching

Batching - Session

doInJPA( this::entityManagerFactory, entityManager -> {

entityManager.unwrap( Session.class ).setJdbcBatchSize( 10 );

for ( long i = 0; i < entityCount; ++i ) {Person = new Person( i, String.format( "Person %d", i ) );entityManager.persist( person );

if ( i % batchSize == 0 ) {entityManager.flush();entityManager.clear();

}}

} );

Batching

DEBUG [main]: n.t.d.l.SLF4JQueryLoggingListener –Name:DATA_SOURCE_PROXY, Time:1, Success:True, Type:Prepared, Batch:True, QuerySize:1, BatchSize:10, Query: ["insert into Person (name, id) values (?, ?)"], Params:[(Person 1, 1), (Person 2, 2), (Person 3, 3), (Person 4, 4), (Person 5, 5), (Person 6, 6), (Person 7, 7), (Person 8, 8), (Person 9, 9), (Person 10, 10)]

Insert PreparedStatement batching (5k rows)

1 10 20 30 40 50 60 70 80 90 100 1000

0

200

400

600

800

1000

1200

1400

1600

Batch size

Tim

e (m

s)

DB_A DB_B DB_C DB_D

Update PreparedStatement batching (5k rows)

1 10 20 30 40 50 60 70 80 90 100 1000

0

100

200

300

400

500

600

700

Batch size

Tim

e (m

s)

DB_A DB_B DB_C DB_D

Delete PreparedStatement batching (5k rows)

1 10 20 30 40 50 60 70 80 90 100 1000

0

200

400

600

800

1000

1200

Batch size

Tim

e (m

s)

DB_A DB_B DB_C DB_D

Batching - Cascading

<property name="hibernate.order_inserts" value="true"/>

<property name="hibernate.order_updates" value="true"/>

Batching – @Version

<property name="hibernate.jdbc.batch_versioned_data" value="true"/>

• Enabled by default in Hibernate 5

• Disabled in Hibernate 3.x, 4.x, and for Oracle 8i, 9i, and 10g dialects

Agenda




• Relationships

• Batching

• Fetching

• Caching

Fetching


• JDBC fetch size

• JDBC ResultSet size

• DTO vs Entity queries

• Fetching relationships

Fetching – JDBC Fetch Size

• Oracle – Default fetch size is 10

• SQL Server – Adaptive buffering

• PostgreSQL, MySQL – Fetch the whole ResultSet at once

• SessionFactory setting:

<property name="hibernate.jdbc.fetch_size" value="100"/>

Fetching - JDBC fetch size

• Query-level hint:

List<PostCommentSummary> summaries = entityManager.createQuery(

"select new PostCommentSummary( " +" p.id, p.title, c.review ) " +"from PostComment c " +"join c.post p")

.setHint(QueryHints.HINT_FETCH_SIZE, fetchSize)

.getResultList();

Fetching – JDBC Fetch Size (10k rows)

1 10 100 1000 10000

0

100

200

300

400

500

600

Fetch size

Tim

e (m

s)

DB_A DB_B DB_C DB_D

Fetching – Pagination

• JPA / Hibernate API works for both entity and native queries

List<PostCommentSummary> summaries = entityManager.createQuery(

"select new PostCommentSummary( " +" p.id, p.title, c.review ) " +"from PostComment c " +"join c.post p")

.setFirstResult(pageStart)

.setMaxResults(pageSize)

.getResultList();

Fetching – 100k vs 100 rows

Fetch all Fetch limit

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Tim

e (m

s)

DB_A DB_B DB_C DB_D

Fetching – Pagination

• Hibernate uses OFFSET pagination

• Keyset pagination scales better when navigating large result sets

• http://use-the-index-luke.com/no-offset

Fetching – Entity vs Projection

• Selecting all columns vs a custom projection

SELECT *FROM post_comment pcINNER JOIN post p ON p.id = pc.post_idINNER JOIN post_details pd ON p.id = pd.id

SELECT pc.versionFROM post_comment pcINNER JOIN post p ON p.id = pc.post_idINNER JOIN post_details pd ON p.id = pd.id

Fetching – Entity vs Projection

All columns Custom projection

0

5

10

15

20

25

30

Tim

e (m

s)

DB_A DB_B DB_C DB_D

Fetching – DTO Projections

• Read-only views

• Tree structures (Recursive CTE)

• Paginated Tables

• Analytics (Window functions)

Fetching – Entity Queries

• Writing data

• Web flows / Multi-request logical transactions

• Application-level repeatable reads

• Detached entities / PersistenceContextType.EXTENDED

• Optimistic concurrency control (e.g. version, dirty properties)

Fetching – Relationships

Association FetchType

@ManyToOne EAGER

@OneToOne EAGER

@OneToMany LAZY

@ManyToMany LAZY

• LAZY associations can be fetched eagerly

• EAGER associations cannot be fetched lazily

Fetching – Best Practices

• Default to FetchType.LAZY

• Fetch directive in JPQL/Criteria API queries

• Entity graphs / @FetchProfile

• LazyInitializationException

Fetching – Open Session in View Anti-Pattern

Fetching – Temporary Session Anti-Pattern

• “Band aid” for LazyInitializationException

• One temporary Session/Connection for every lazily fetched association

<property name="hibernate.enable_lazy_load_no_trans" value="true"/>

Agenda




• Relationships

• Batching

• Fetching

• Caching

Caching


Caching – Why 2nd - Level Caching

Caching – Why 2nd - Level Caching

“There are only two hard things in Computer Science: cache invalidation and naming

things.”

Phil Karlton

Caching – Strategies

Strategy Cache type Particularity

READ_ONLY READ-THROUGH Immutable

NONSTRICT_READ_WRITE READ-THROUGH Invalidation/

Inconsistency risk

READ_WRITE WRITE-THROUGH Soft Locks

TRANSACTIONAL WRITE-THROUGH JTA

Caching – Collection Cache

• It complement entity caching

• It stores only entity identifiers

• Read-Through

• Invalidation-based (Consistency over Performance)

Caching – Read - Write Aggregates

Questions and Answers

https://leanpub.com/high-performance-java-persistence




• Relationships

• Batching

• Fetching

• Caching

Software

High Performance Hibernate JavaZone 2016