You can pass options to the JVM via -J.  E.g.,

    scala -J-Xmx2g ...

The JAVA_OPTS environment variable is used to specify the options passed to the java command. See the [Scala manpage][1] for details.


  [1]: http://www.scala-lang.org/files/archive/nightly/docs/manual/html/scala.html

Based on Joe&#39;s suggestion, I looked at the scala program, which is a Bash script that calls java with various Scala specific arguments. It allows extra command line arguments to be passed to Java through the JAVA_OPTS environment variable. So you can increase the heap size like this:

    JAVA_OPTS=&quot;-Xmx2g&quot; scala classname arguments...


As a hack you can edit the `scala/bin/scala` file to edit the parameters for the `java` command. Not pretty.

Is there any reason why Nose wouldn&#39;t be able to find tests in Ubuntu 9.04? 

I&#39;m using nose 0.11.1 with python 2.5.4.  
I can run tests only if I explicitly specify the filename. 
If I don&#39;t specify the filename it just says, **0 tests**. 

The same project runs tests fine on my Mac, so I&#39;m quite stumped!

Nose unable to find tests in ubuntu

GCC compiler supports __builtin_expect statement that is used to define likely and unlikely macros.

eg.

    #define likely(expr)    (__builtin_expect(!!(expr), 1))
    #define unlikely(expr)  (__builtin_expect(!!(expr), 0))

Is there an equivalent statement for the Microsoft Visual C compiler, or something equivalent ?


likely/unlikely equivalent for MSVC

I have a Scala data processing tool which is failing with a `java.lang.OutOfMemoryError` exception. The tool needs to make a couple passes over a large data file (the one I&#39;m working on is over 700MB), so it would be convenient if the entire thing could be stored in memory.

I run the tool from the command line or from a Bash script using the &quot;scala&quot; runner. How do I increase the JVM heap size for this? I&#39;ve tried passing `-Xmx1024m`, but it does not recognize this argument. I&#39;m using a nightly build of Scala 2.8.0 (r18678).

Increase JVM heap size for Scala?

<p>I have a Scala data processing tool which is failing with a <code>java.lang.OutOfMemoryError</code> exception. The tool needs to make a couple passes over a large data file (the one I'm working on is over 700MB), so it would be convenient if the entire thing could be stored in memory.</p>
<p>I run the tool from the command line or from a Bash script using the "scala" runner. How do I increase the JVM heap size for this? I've tried passing <code>-Xmx1024m</code>, but it does not recognize this argument. I'm using a nightly build of Scala 2.8.0 (r18678).</p>


In Scala, what&#39;s the best way to dynamically instantiate an object and invoke a method using reflection?

I would like to do Scala-equivalent of the following Java code:

    Class class = Class.forName(&quot;Foo&quot;);
    Object foo = class.newInstance();
    Method method = class.getMethod(&quot;hello&quot;, null);
    method.invoke(foo, null);

In the above code, both the class name and the method name are passed in dynamically. The above Java mechanism could probably be used for `Foo` and `hello()`, but the Scala types don&#39;t match one-to-one with that of Java. For example, a class may be declared implicitly for a singleton object. Also Scala method allows all sorts of symbols to be its name. Both are resolved by name mangling. See [Interop Between Java and Scala][1].

Another issue seems to be the matching of parameters by resolving overloads and autoboxing, described in [Reflection from Scala - Heaven and Hell][2].  

  [1]: http://www.codecommit.com/blog/java/interop-between-java-and-scala
  [2]: http://www.familie-kneissl.org/Members/martin/blog/reflection-from-scala-heaven-and-hell

Scala: How do I dynamically instantiate an object and invoke a method using reflection?

In Java you can write &lt;code&gt;Boolean.valueOf(myString)&lt;/code&gt;. However in Scala, &lt;code&gt;java.lang.Boolean&lt;/code&gt; is hidden by &lt;code&gt;scala.Boolean&lt;/code&gt; which lacks this function. It&#39;s easy enough to switch to using the original Java version of a boolean, but that just doesn&#39;t seem right.

So what is the one-line, canonical solution in Scala for extracting &lt;code&gt;true&lt;/code&gt; from a string?

Scala: Elegant conversion of a string into a boolean

Where can I find a list of Scala&#39;s &quot;magic&quot; functions, such as `apply`, `unapply`, `update`, `+=`, etc.?

By magic-functions I mean functions which are used by some syntactic sugar of the compiler, for example

    o.update(x,y) &lt;=&gt; o(x) = y

I googled for some combination of `scala` `magic` and synonyms of `functions`, but I didn&#39;t find anything.

I&#39;m not interested with the *usage* of magic functions in the standard library, but in which magic functions exists.



List of Scala&#39;s &quot;magic&quot; functions

I&#39;ve just started learning Scala, and the first thing I&#39;m going to implement is a tiny web application. I&#39;ve been using [Erlang][1] for the last year to implement server-side software, but I&#39;ve never wrote web applications before. It will be a great experience.

Are there web-frameworks for Scala except for [Lift][2]?

Don&#39;t get me wrong, Lift looks awesome. I just want to know how many frameworks there are so that I can then choose between them. It&#39;s always a good to have a choice, but I the only thing I found was Lift.

  [1]: http://en.wikipedia.org/wiki/Erlang_%28programming_language%29
  [2]: http://en.wikipedia.org/wiki/Lift_%28web_framework%29


What Scala web-frameworks are available?

I want to be able to declare something like this:

    trait Narrowable[A] extends Iterable[A] {
  
        def narrow[B &lt;: A &amp; B &lt;: AnyRef] : Iterable[B]

    }

That it, the type `B` should be both a subtype of `A` *and* `AnyRef`. Is this possible?

How do I setup multiple type bounds in Scala?

Is there any way to run command prompt commands from within a C# application?  If so how would I do the following:

    copy /b Image1.jpg + Archive.rar Image2.jpg

This basically embeds an RAR file within JPG image.  I was just wondering if there was a way to do this automatically in C#.

Run Command Prompt Commands

I&#39;m trying to create a right-click context menu command for compressing JavaScript files with YUI compressor. My ultimate goal is to try to get this to run on a context menu:

    java.exe -jar yuicompressor-2.4.2.jar -o &lt;filename&gt;.min.js &lt;filename&gt;.js

I know I can use the variable `%1` to reference the file name being opened. I can&#39;t figure out how to get this command into a batch file syntax and haven&#39;t been able to find any answers online.

**Update:**  
Jeremy&#39;s answer (+comments) worked. For anyone who stumbles upon this, here is what I had to do:

In the action I created for the JavaScript file, I used this as the command:

    minify.bat &quot;%1&quot;

Which calls my batch script, which looks like this:

    java.exe -jar yuicompressor-2.4.2.jar -o &quot;%~dpn1.min.js&quot; %1

For the batch script, keep in mind that the code above assumes the directories for java.exe &amp; yuicompressor are both added to your `PATH` variables. If you don&#39;t add these to your path, you&#39;ll have to use the full path for the files.

The sequence `%~dpn` is used to get:

 1. `%~d` - The drive
 2. `%~p` - The path
 3. `%~n` - The file name



Getting the file name without extension in a Windows Batch Script

Inside my bash script, I would like to parse zero, one or two parameters (the script can recognize them), then forward the remaining parameters to a command invoked in the script. How can I do that?


How do I forward parameters to other command in bash script?

I&#39;m looking to be able to run a single query on a remote server in a scripted task.

For example, intuitively, I would imagine it would go something like:

    mysql -uroot -p -hslavedb.mydomain.com mydb_production &quot;select * from users;&quot;



How do you run a single query through mysql from the command line?

Is it possible to catch the &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;C&lt;/kbd&gt; signal in a java command-line application? I&#39;d like to clean up some resources before terminating the program.

Catching Ctrl+C in Java

I need to check if some option that can be passed to JVM is explicitly set or has its default value.

To be more specific:
I need to create one specific thread with higher native stack size than the default one, but in case the user wants to take care of such things by himself by specifying the `-Xss` option I want to create all threads with default stack size (which will be specified by user in -Xss option).

I&#39;ve checked classes like `java.lang.System` and `java.lang.Runtime`, but these aren&#39;t giving me any useful information about VM arguments.

Is there any way to get the information I need?


How to get VM arguments from inside of Java application?

Is there some way to see the native code produces by the JIT in a JVM?

How to see JIT-compiled code in JVM?

I&#39;m reading [this article][1] about how JVM invokes methods, and I think I got most of it. However, I&#39;m still having trouble understanding the need for `invokeinterface`.

The way I understand it, a class basically has a virtual table of methods and when calling a method with either `invokevirtual` or `invokeinterface` this virtual table is consulted.

What is the difference, then, between a method that&#39;s defined on an interface and a method defined on a base class? Why the different bytecodes?

The [description of the instructions][2] also looks very similar.

The article seems to claim that the method table of an interface can have &quot;different offsets&quot; every time a method is called. What I don&#39;t understand is why an interface would have a method table at all, since no object can have the interface as its actual type.

What am I missing?

  [1]: http://www.javaworld.com/javaworld/jw-06-1997/jw-06-hood.html?page=1
  [2]: http://java.sun.com/docs/books/jvms/second_edition/html/Instructions2.doc6.html

What is the point of invokeinterface?

I have already read various accounts of Clojure vs. Scala and while I realize that both have their place.  There are a few considerations that I haven&#39;t acquired a complete explanation on when it comes to comparing both Clojure with Scala:

1.) Which of the two languages is generally *faster*?  I realize that this will vary from one language feature to another but an general assessment of performance would be helpful.  For example: I know that Python dictionaries are really fast.  But as a whole, it is a *much* slower language than Java.  I don&#39;t want to go with Clojure and run into this problem down the road.

2.) How is interoperability with Java?  All I have read so far is that Scala has native collections types that make it a bit clumsy to integrate with a large Java code-base, whereas Clojure follows a simple Iterable/Iterator-centric way to inter-operate with Java classes.  Any more thoughts/details on this?

Ultimately, if it is a close enough draw between clojure and scala, I might try them both.  One thing about Clojure is the language seems *very* simple.  But then again, Scala has a very flexible type system.  But, I know that Scala is fast (based on multiple personal accounts).  So, if Clojure is significantly slower: I&#39;d like to know sooner rather than later.

On Performance and Java Interoperability: Clojure vs. Scala

Sometimes, I&#39;ll run a program that accidentally contains an infinite loop or something. Eclipse will let me continue editing the program, but be super slow. How can I stop it? (Do I want to restart the JVM?) Restarting eclipse itself always works, but that breaks my workflow.

Eclipse: stop code from running (java)

I am working on a Windows 2003 server (64-bit) with 8 GB RAM. How can I increase the heap memory maximum? I am using the `-Xmx1500m` flag to increase the heap size to 1500 Mb. Can I increase the heap memory to 75% of physical memory (6 GB Heap)?
 

Increase heap size in Java

I am getting the following error on execution of a multi-threading program

    java.lang.OutOfMemoryError: Java heap space

The above error occured in one of the threads.

1. Upto my knowledge, Heap space is occupied by instance variables only. If this is correct, then why this error occurred after running fine for sometime as space for instance variables are alloted at the time of object creation.

2. Is there any way to increase the heap space?

3. What changes should I made to my program so that It will grab less heap space?

 

java.lang.OutOfMemoryError: Java heap space

Why are the runtime heap used for dynamic memory allocation in C-style languages and [the data structure][1] both called &quot;the heap&quot;? Is there some relation?


  [1]: http://en.wikipedia.org/wiki/Heap_(data_structure)

Why are two different concepts both called &quot;heap&quot;?

I think I increased my heap size to 1 GB in NetBeans since I changed the config to look like this:


    netbeans_default_options=&quot;-J-Xmx1g ......


After I restarted NetBeans, can I be sure that my app is given 1 GB now?

Is there a way to verify this?

How to view the current heap size that an application is using?

List your favorite heap analysis tools (e.g. jprofiler, jmap, ...).
Let&#39;s keep it one tool per answer, with a short list of pros and cons for each tool.

Content Type	Original Author	Original Content on Stackoverflow
Question	Jay Conrod	View Question on Stackoverflow
Solution 1 - Scala	Geoffrey Irving	View Answer on Stackoverflow
Solution 2 - Scala	Synesso	View Answer on Stackoverflow
Solution 3 - Scala	Jay Conrod	View Answer on Stackoverflow
Solution 4 - Scala	Daniel C. Sobral	View Answer on Stackoverflow
Solution 5 - Scala	Joe	View Answer on Stackoverflow

Increase JVM heap size for Scala?

Scala Problem Overview

Scala Solutions

Solution 1 - Scala

Solution 2 - Scala

Solution 3 - Scala

Solution 4 - Scala

Solution 5 - Scala

likely/unlikely equivalent for MSVC

Nose unable to find tests in ubuntu

Attributions