fsc – Fast offline compiler for the Scala 2 language


fsc [ <options> ] <source files>


Command line options. See OPTIONS below.
<source files>
One or more source files to be compiled (such as MyClass.scala).


The offline compiler supports all options of scalac plus the following:

Reset compile server caches.
Shut down the compilation daemon. The daemon attempts to restart itself as necessary, but sometimes an explicit shutdown is required. A common example is if jars on the class path have changed.
–server <hostname:portnumber>
Specify compile server host at port number. Usually this option is not needed. Note that the hostname must be for a host that shares the same filesystem.
–J <flag>
Pass <flag> directly to the Java VM for the compilation daemon.


The fsc tool submits Scala compilation jobs to a compilation daemon. The first time it is executed, the daemon is started automatically. On subsequent runs, the same daemon can be reused, thus resulting in a faster compilation. The tool is especially effective when repeatedly compiling with the same class paths, because the compilation daemon can reuse a compiler instance.

The compilation daemon is smart enough to flush its cached compiler when the class path changes. However, if the contents of the class path change, for example due to upgrading a library, then the daemon should be explicitly shut down with -shutdown.

Note that the scala script runner will also use the offline compiler by default, with the same advantages and caveats.


The following session shows a typical speed up due to using the offline compiler.

> fsc -verbose -d /tmp test.scala
[Port number: 32834]
[Starting new Scala compile server instance]
[Classpath = ...]
[loaded directory path ... in 692ms]
[parsing test.scala]
[total in 943ms]

> fsc -verbose -d /tmp test.scala
[Port number: 32834]
[parsing test.scala]
[total in 60ms]

> fsc -verbose -d /tmp test.scala
[Port number: 32834]
[parsing test.scala]
[total in 42ms]

> fsc -verbose -shutdown
[Scala compile server exited]


Specify the java command to be used for running the Scala code. Arguments may be specified as part of the environment variable; spaces, quotation marks, etc., will be passed directly to the shell for expansion.
Specify JDK/JRE home directory. This directory is used to locate the java command unless JAVACMD variable set.
Specify the options to be passed to the java command defined by JAVACMD.
With Java 1.5 (or newer) one may for example configure the memory usage of the JVM as follows: JAVA_OPTS="-Xmx512M -Xms16M -Xss16M"
With GNU Java one may configure the memory usage of the GIJ as follows: JAVA_OPTS="--mx512m --ms16m"


fsc returns a zero exit status if it succeeds to compile the specified input files. Non zero is returned in case of failure.


Written by Martin Odersky and other members of the Scala team.


Report bugs to http://lampsvn.epfl.ch/trac/scala.

This is open-source software, available to you under a BSD-like license. See accomponying "copyright" or "LICENSE" file for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


sbaz(1), scala(1), scalac(1), scaladoc(1), scalap(1)

version 0.4
January 18, 2007