Question

I am embedding JRuby using Red Bridge into an app and seem to have problems setting out and err. My tests use a PrintStream that writes to a StringBuilder, after doing some stuff with the JRuby, I then check the stuff printed to out with puts. The problem is only the first setOutput works everyting gets printed to that.

The simple sample below demonstrates the problem. It is using PrintStreams that write to different files to demonstrate the problem. Looking at your file system will show that everything goes to the first “file” when one would expect files 2 and 3 to also be written.

package XXX.jruby;

import java.io.PrintStream;

import org.jruby.embed.LocalContextScope;
import org.jruby.embed.LocalVariableBehavior;
import org.jruby.embed.ScriptingContainer;

public class JRubyShellPutsProblem {

    public static void main(String[] args) throws Exception {
        for (int i = 0; i < 3; i++) {
            final ScriptingContainer container = new ScriptingContainer(LocalContextScope.CONCURRENT, LocalVariableBehavior.PERSISTENT);
            // container.resetWriter();
            // container.resetErrorWriter();

            final PrintStream printStream = new PrintStream("d:\\out" + i + ".txt");
            container.setOutput(printStream);
            container.setError(printStream);

            container.runScriptlet("puts \"hello" + i + "\"\n");
            printStream.flush();
            container.terminate();
        }
    }
}

I’ve tried ScriptingContainer.resetWriter but that does not work as one would expect. Sometimes stuff gets written to files 1 and 2 but nothing to 3.

Answer 1

I changed LocalContextScope to THREADSAFE from CONCURRENT and this seemed to fix the problem.