Setup

Version 7, last updated by Anonymous at July 12, 2011 08:47 UTC

To have a better experience with Scala-IDE, this page try to collect information to help you configure eclipse, and avoid some Troubleshooting

eclipse.ini

The default Eclipse heap configuration is often inadequate for the Scala IDE. It is strongly recommended that you edit your eclipse/eclipse.ini to add the following lines increasing various heap limits and VM options:

--launcher.XXMaxPermSize
256m
-vmargs
-Xms256m
-Xmx1024m
-XX:PermSize=64m
-Xss1M
-server
-XX:+DoEscapeAnalysis

The configuration above specifies a 1Gb maximum heap size. If the machine you are running the Scala IDE on has sufficient physical memory (eg. > 3GB) then specifying -Xmx2048m for a 2Gb heap might be beneficial.

If you are using a recent Oracle JVM you might also find it beneficial to add,

-XX:+UseConcMarkSweepGC

and if you are using the Oracle 64 bit JVM you should also add,

-XX:+UseCompressedOops

Required Preferences

The ScalaIDE use AOP to tweak JDT, so you need to enable JDT weaving, else scala files are managed as java file. So check if it enabled (else Click to ENABLE)

  Window > Preferences > JDT Weaving
  || JDT Weaving is currently ENABLED

Optional Preferences

Display heap status, when eclipse is near the limit, GC activity increase (when scalac runs,...) and the system slow down
```
Window > Preferences > General
|| [x] Show heap status
```

Limit the number of open editors

Window > Preferences > General > Editors
|| [x] Close editors automatically
||   Number of opened editors before closing: 12

Lot of content assistant require information provide by compiler (Types,...), as Scala-IDE is build over JDT, java content assistant are enabled for scala files. Disable auto-activation (on typing instead of explicit calls) can reduce number of freeze,...
```
Window > Preferences > Java > Editor > Content Assist
|| [ ] Enable auto-activation
```

But you should have completion (enable Word Proposals if you don't want to know several shortcuts)

Window > Preferences > Java > Editor > Content Assist > Advanced
|| [X] Java Proposals
|| [X] Template Proposals
|| [X] Word Proposals

Performance

GC activity and swap are killer : freeze eclipse,... full system.

So monitor and tweak when possible (may be, close your browser, flash apps,...).

To monitor swap / CPU, you can use your native system monitor (, some system monitors are performance killers themselves).
To monitor GC activity, connect jvisualvm (a profiling tool provide with jdk 1.6.0) to your eclipse instance (see wip_tuning for some screenshot of GC activity that freeze eclipse). Or "smell it" via heap memory usage, you can show heap status (see above if there is enough free memory, then gc will not consume CPU ).

Suggested Plugins

Nice keyboard shortcut

Alt+Shift+X S : run As Scala Application , quicker than popup menu because it doesn't need to scan every Launcher to see what is possible (could require full recompilation in background => freeze)
Alt+Shift+X T : run As JUnit , quicker than popup menu because it doesn't need to scan every Launcher to see what is possible (could require full recompilation in background => freeze)
Ctrl+Space : completion (by code, templates,...)
Alt+/ : complete word
Ctrl+/ : toggle comment of block (selected line(s) or current line)

Scala IDE for Eclipse