Nearly every Eclipse user is aware what Xtext is and what it is useful for. It is always a pleasure to see in which kind of areas it is used. One reason is clearly, that it is really easy to build a first working example in no time. The grammar alone is sufficient and the rest is done by a code generator. Xtext will generate stub classes, that are ready to fill in individual logic for different areas. By doing that most of the things just work, because Xtext comes with a lot of defaults that suits in most of the cases. But as projects get bigger and the amount of models grow, the defaults might not scale and you might need to tweak your language to make working smooth again. Here it becomes more complicated and you need to understand what’s going on under the covers. In this session I will go through typical problems and solutions, that we have seen in customer projects. Sometimes it’s a tradeoff to tackle those problems, but it’s important to understand the implications. For some typical examples I will go into details and explain what’s going on under the covers. After the session attendees should have an idea how to tweak their own languages and why it might be worth the effort to migrate to a newer version of Xtext.

1. Xtext beyond the defaults
How to tackle performance problems

2. Who is that guy?

7. Xtext defaults are a good start!
But one size does not fit all!

8. Xtext defaults are a good start!
But one size does not fit all!
Amount of DSLs increases

9. Xtext defaults are a good start!
But one size does not fit all!
Amount of DSLs increases
Files get bigger

10. Xtext defaults are a good start!
But one size does not fit all!
Amount of DSLs increases
Files get bigger
Amount of files increases

11. Xtext defaults are a good start!
But one size does not fit all!
Amount of DSLs increases
Files get bigger
Amount of files increases
Many cross references

12. Xtext defaults are a good start!
But one size does not fit all!
Amount of DSLs increases
Files get bigger
Amount of files increases
Many cross references
Maybe transitive cross references…

13. Look what we have build!

14. Look what we have build!
More than 20 DSLs…

15. Look what we have build!
More than 20 DSLs…
and 200.000 lines in one file…

16. Look what we have build!
More than 20 DSLs…
and 200.000 lines in one file…
and we can check in broken models…

17. Look what we have build!
More than 20 DSLs…
and 200.000 lines in one file…
and we can check in broken models…
and we generate the missing stuff…

18. Look what we have build!
More than 20 DSLs…
and 200.000 lines in one file…
and we can check in broken models…
and we generate the missing stuff…
to make them valid again!

19. Look what we have build!
More than 20 DSLs…
and 200.000 lines in one file…
We are on Xtext 2.6.2 and can’t update!
and we can check in broken models…
and we generate the missing stuff…
to make them valid again!

20. Look what we have build!
More than 20 DSLs…
and 200.000 lines in one file…
We are on Xtext 2.6.2 and can’t update!
and we can check in broken models…
and we generate the missing stuff…
to make them valid again!
Could you please back-port the changes?

21. Everything is sooo slow!!!
Xtext sucks!!!

22. Finally think about improving the situation!

23. Update to newest Xtext Version
2.10.x

24. Update to newest Xtext Version
2.10.x
Xtext 2.11
released
early
2017

25. Why should I update???

26. Because…we killed bugs…

27. Because…we killed bugs…
Let workarounds
not last forever!

28. …Speed…

29. …Speed…
Resolving
cross-
references
has
never
been
faster…

30. …new features…

31. …new features…
Make
Xtext work
with
other
platform
s

32. …let’s work together.

33. …let’s work together.
It was
never
easier
to
contribute!
We
are
on
G
ithub
:-D

34. What about Performance…

35. Most problems happen in…
…Index and scoping…
…Memory consumption.
Validations…
… Complex generators…

36. I need Xbase in every language…

37. I need Xbase in every language…
… because my language is
complicated…

38. I need Xbase in every language…
… because my language is
complicated…
… no I can’t explain why…

39. I need Xbase in every language…
… because my language is
complicated…
… no I can’t explain why…
… but there is this small corner case…

40. Is a FAST validation really fast…

41. Is a FAST validation really fast…
… it’s triggered every time I stop typing

42. Scoping is sooo complicated…

43. Scoping is sooo complicated…
… I heard that in nearly every project…

44. Scoping is sooo complicated…
… I heard that in nearly every project…
…and people stop improving things when
it work’s for the first time…

45. Scoping is sooo complicated…
… I heard that in nearly every project…
…and people stop improving things when
it work’s for the first time…
… code is not touched any more because
who knows…

46. Scoping is sooo complicated…
… I heard that in nearly every project…
…and people stop improving things when
it work’s for the first time…
… code is not touched any more because
who knows…
… it worked before you touched it!

47. What’s the problem?
LocalScope
GlobalScope
ImportScopeTypeScope
Caches everywhere
The Index
Lazylinking
EcoreUtils.resolveAll should do the trick!
DerivedState
ContainerState
BatchLinkableResource

48. Scoping API
scope_Element_feature(Element element ,EReference ref)

49. Scoping API
scope_Element_feature(Element element ,EReference ref)

50. Scoping API
scope_Element_feature(Element element ,EReference ref)

51. Scoping API
scope_Element_feature(Element element ,EReference ref)

52. Scoping API
scope_Element_feature(Element element ,EReference ref)
Called by the PolymorphicDispatcher…

53. Scoping API
scope_Element_feature(Element element ,EReference ref)
Called by the PolymorphicDispatcher…
…in a reflective way…

54. Scoping API
scope_Element_feature(Element element ,EReference ref)
Called by the PolymorphicDispatcher…
and if grammar changed it might not get called any more…
…in a reflective way…

55. Scoping API
scope_Element_feature(Element element ,EReference ref)
Called by the PolymorphicDispatcher…
and if grammar changed it might not get called any more…
…in a reflective way…
…BECAUSE IT’S SLOW!

56. Scoping API
scope_Element_feature(Element element ,EReference ref)
Called by the PolymorphicDispatcher…
and if grammar changed it might not get called any more…
…in a reflective way…
…BECAUSE IT’S SLOW!
Implement
getScope(EObject context, EReference ref)
if(context instanceof Element && ref ==
MyPackage.Literals.ELEMENT_FEATURE)
up to 10 %

57. Scoping API
scope_Element_feature(Element element ,EReference ref)
Called by the PolymorphicDispatcher…
and if grammar changed it might not get called any more…
…in a reflective way…
…BECAUSE IT’S SLOW!
Implement
getScope(EObject context, EReference ref)
if(context instanceof Element && ref ==
MyPackage.Literals.ELEMENT_FEATURE)
up to 10 %Will not work
with
Xbase
anyway…

58. Use caches in the ScopeProvider

59. Use caches in the ScopeProvider
For each cross reference the ScopeProvider gets asked…

60. Use caches in the ScopeProvider
…and it calculates the very same stuff
over and over again…
For each cross reference the ScopeProvider gets asked…

61. Use caches in the ScopeProvider
…and it calculates the very same stuff
over and over again…
For each cross reference the ScopeProvider gets asked…
…cache the calculated stuff and invalidate it when
necessary!

62. Use caches in the ScopeProvider
…and it calculates the very same stuff
over and over again…
For each cross reference the ScopeProvider gets asked…
…cache the calculated stuff and invalidate it when
necessary!
The cache of the GlobalScope should be the index and
nothing else!

63. Use the force of the Index

64. Use the force of the Index
Holds all lightweight representations of
referenceable elements and their resources

65. Use the force of the Index
Holds all lightweight representations of
referenceable elements and their resources
It’s a HashMap…
It’s super fast since Xtext 2.x
and improved further

66. Holds all lightweight representations of
referenceable elements and their resources
Use the force of the Index
It’s a HashMap…
It’s super fast since Xtext 2.x
and improved further
It’s YOUR Index - you can put data in…!

67. Index - how to feed it

68. Index - how to feed it
1. Builder picks up DSL files and loads them one by one

69. Index - how to feed it
1. Builder picks up DSL files and loads them one by one
2. Creates ResourceDescriptions through ResourceDescriptionManager

70. Index - how to feed it
1. Builder picks up DSL files and loads them one by one
2. Creates ResourceDescriptions through ResourceDescriptionManager
3. ResourceDescriptionManager calls ResourceDescriptionsStrategy to
create EObjectDescriptions

71. Index - how to feed it
1. Builder picks up DSL files and loads them one by one
2. Creates ResourceDescriptions through ResourceDescriptionManager
3. ResourceDescriptionManager calls ResourceDescriptionsStrategy to
create EObjectDescriptions
You have to bind a custom impl for the ResourceDescriptionsStrategy in
the RuntimeModule

72. Index - how to feed it
1. Builder picks up DSL files and loads them one by one
2. Creates ResourceDescriptions through ResourceDescriptionManager
3. ResourceDescriptionManager calls ResourceDescriptionsStrategy to
create EObjectDescriptions
You have to bind a custom impl for the ResourceDescriptionsStrategy in
the RuntimeModule
The default creates a EObjectDescription for
EVERY Element that has a name…

73. IEObjectDescription create(String simpleName, EObject element, Map<String, String> userData)
Information hiding and userData

74. IEObjectDescription create(String simpleName, EObject element, Map<String, String> userData)
Information hiding and userData

75. IEObjectDescription create(String simpleName, EObject element, Map<String, String> userData)
Information hiding and userData

76. IEObjectDescription create(String simpleName, EObject element, Map<String, String> userData)
Information hiding and userData
Save memory & time

77. UserData - what for?

78. UserData - what for?
Validation
Don’t load the world to get informations - put
them in the index

79. UserData - what for?
Validation
Don’t load the world to get informations - put
them in the index
Scoping
Don’t resolve proxies for simple informations

80. Reference non Xtext models

81. Reference non Xtext models
We have our own GlobalScopeProvider that does the trick…

82. Reference non Xtext models
We have our own GlobalScopeProvider that does the trick…
…we load everything and the GlobalScope contains the
corresponding EObjectDescriptions…

83. Reference non Xtext models
We have our own GlobalScopeProvider that does the trick…
…we load everything and the GlobalScope contains the
corresponding EObjectDescriptions…
…but it’s slow and we cannot navigate those elements in the
editor…
You can do better…

84. Reuse the Xtext infrastructure

85. Reuse the Xtext infrastructure
Bind a ResourceServiceProvider…
…so that you can put the elements in the index and make
them navigable!

86. Reuse the Xtext infrastructure
Bind a ResourceServiceProvider…
…so that you can put the elements in the index and make
them navigable!
GenericResourceServiceProvider
Use
It will put everything that has a name in the index…
… introduce your own ResourceDescriptionStrategy!

87. But the builder picks them up…
and it takes ages!

88. Put the index in the jar

89. Put the index in the jar
Why calculating the index of a static set of files?

90. Put the index in the jar
The index is serialisable…
…put it in the jar and load it.
Why calculating the index of a static set of files?

91. Index in Standalone
It’s sooo slow…

92. Index in Standalone
It’s sooo slow…
…of course I have my custom Standalone impl…

93. Index in Standalone
ResourceSetGlobalScopeProvider
Long time the
was the default.

94. Index in Standalone
ResourceSetGlobalScopeProvider
Long time the
was the default.
Today we can do better but you need to use it and know that
there is something new…
For Maven- and Gradleplugin it’s done.

95. Index in Standalone
Fill the index and install it on the ResourceSet!
Load each resource and ask the ResourceDescriptionManager
to create a ResourceDescription…

96. Index in Standalone
Fill the index and install it on the ResourceSet!
Load each resource and ask the ResourceDescriptionManager
to create a ResourceDescription…
Install it on the ResourceSet

97. Make big things run again and save your ass!
Up to 80% more faster in 10 minutes!

98. Codegenerators
They are sooo slow…

99. Codegenerators
They are sooo slow…
… of course I am using mwe2 to invoke it…

100. Codegenerators
They are sooo slow…
… of course I am using mwe2 to invoke it…
… even in the IDE!

101. Incremental generators

102. Incremental generators
The builder triggers the generator for each resource…

103. Incremental generators
The builder triggers the generator for each resource…
…when a file changes the builder computes the impact and
retriggers the generator for each affected file!

104. Incremental generators
The builder triggers the generator for each resource…
…when a file changes the builder computes the impact and
retriggers the generator for each affected file!
What about m:n scenarios?
Solveable with a little effort - but it is worth the work!

105. Incremental generators
The builder triggers the generator for each resource…
…when a file changes the builder computes the impact and
retriggers the generator for each affected file!
What about m:n scenarios?
Solveable with a little effort - but it is worth the work!
There is a ParallelBuilderParticipant…
…you have to bind it for your language…
… make sure all proxies are already resolved!

106. Memory consumption

107. Memory consumption
DisabledClusteringPolicy
Do not unload resource…

108. Memory consumption
DisabledClusteringPolicy
DynamicResourceClusteringPolicy
Do not unload resource…
Unload resources when there is no free memory…
…can be configured.

109. The NodeModel is huge
Stores the syntax tree with text and positions…

110. The NodeModel is huge
Stores the syntax tree with text and positions…
…is used to get the position of a specific element or
feature…

111. The NodeModel is huge
Stores the syntax tree with text and positions…
…is used to get the position of a specific element or
feature…
…produces a lot of Strings in memory…

112. The NodeModel is huge
Stores the syntax tree with text and positions…
…is used to get the position of a specific element or
feature…
…produces a lot of Strings in memory…
…and during the builder runs you do not really need
it.

113. Switch off the NodeModel

114. Switch off the NodeModel
The parser creates it …

115. Switch off the NodeModel
The parser creates it …
…it is used to install proxies - so you have to do that
differently…

116. Switch off the NodeModel
The parser creates it …
…it is used to install proxies - so you have to do that
differently…
You want to have it when the editor is used…

117. Switch off the NodeModel
The parser creates it …
…it is used to install proxies - so you have to do that
differently…
You want to have it when the editor is used…
… the load options should be an indicator…

118. Switch off the NodeModel
The parser creates it …
…it is used to install proxies - so you have to do that
differently…
You want to have it when the editor is used…
… the load options should be an indicator…
…what are the implications?

119. Implications
You cannot use the NodeModel in validations and
scoping any more…

120. Implications
You cannot use the NodeModel in validations and
scoping any more…
…Issues are marked at position 0,0…
…an EditorCallback should revalidate the content.

121. Implications
You cannot use the NodeModel in validations and
scoping any more…
…Issues are marked at position 0,0…
…an EditorCallback should revalidate the content.
THIS IS NOT A COMMON THING!
DO IT ONLY WHEN IT IS REALLY NECESSARY!

122. Order makes a difference

123. Order makes a difference
Files might belong together…

124. Order makes a difference
Files might belong together…
…and might reference each other.

125. Order makes a difference
Files might belong together…
…and might reference each other.
Putting them in an logical order for the builder…

126. Order makes a difference
Files might belong together…
…and might reference each other.
Putting them in an logical order for the builder…
… and they do not have be loaded more than once.

127. Order makes a difference
Files might belong together…
…and might reference each other.
Putting them in an logical order for the builder…
… and they do not have be loaded more than once.
Sometimes it makes sense to not unload them at all.

128. Now you know!

129. Professional Support