FULL PRODUCT VERSION :
build 1.6.0_02-ea-b02

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
Dual Core Pentium Dell Latitude D620

A DESCRIPTION OF THE PROBLEM :
Compiling multiple .java files that use unboxing syntax in parallel using the 1.6 compiler fails with perplexing errors such as "Fatal Error: Unable to find method doubleValue," "Fatal Error: Unable to find method intValue," and "Fatal Error: Unable to find method booleanValue."

We have successfully compiled our application using JDK 1.5. When we tried compiling using JDK 1.6 we encountered many of the above errors. We narrowed the issue down to our use of the <parallel> ant task -- our build compiles multiple modules in parallel, taking advantage of multiple core/processor machines. When we remove the <parallel> task, forcing each module to compile in series, the problem goes away. However, this solution increases our build time by 50%. The problem also disappears when we invoke javac with fork="true." A better solution, but it seems wasteful to fork for every compile and some tasks (e.g., jasper2) don't provide forking as an option.

This issue is easily reproducible with simple test cases on a dual-core Windows XP PC using JDK 1.6.0_01 and 1.6.0_02. We've demonstrated the problem both using ant and calling com.sun.tools.javac.Main.compile() directly from multiple Java threads.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a directory with the six files listed below on a dual-core PC with JDK 1.6. Attempt to build the test files using build.xml:

     ant test

Or by compiling and running CompilerTest.java:

     test



EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The test files should compile without error.
ACTUAL -
Exact compiler output changes from run to run, but the compile always fails. One example:

Test2.java:7: cannot find symbol
symbol : method doubleValue()
location: class java.lang.Double
        double d = d0;
                   ^
Test3.java:7: cannot find symbol
symbol : method doubleValue()
location: class java.lang.Double
        double d = d0;
                   ^
Fatal Error: Unable to find method doubleValue
Fatal Error: Unable to find method doubleValue

ERROR MESSAGES/STACK TRACES THAT OCCUR :
See above

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
Below are:

- Three test files (Test1.java, Test2.java, Test3.java)
- An ant build script that attempts to build the test files in series & parallel
- A java class + shell script that build the test files in series & parallel by invoking the compiler from multiple java threads

== Test1.java ==

public class Test1
{
    private Double d0 = 0.0;

    public void test()
    {
        double d = d0;
    }
}

== Test2.java ==

public class Test2
{
    private Double d0 = 0.0;

    public void test()
    {
        double d = d0;
    }
}

== Test3.java ==

public class Test3
{
    private Double d0 = 0.0;

    public void test()
    {
        double d = d0;
    }
}

== build.xml ==

<?xml version="1.0" encoding="ISO-8859-1"?>

<project name="JDK Bug" default="test" basedir=".">
    <target name="test">
        <antcall target="series"/>
        <antcall target="fork"/>
        <antcall target="parallel"/>
    </target>

    <target name="clean">
        <delete>
            <fileset dir="." includes="*.class"/>
        </delete>
    </target>

    <target name="series" depends="clean">
        <echo>===== Testing in series =====</echo>
        <property name="fork" value="false"/>
     <antcall target="test1"/>
     <antcall target="test2"/>
     <antcall target="test3"/>
    </target>

    <target name="fork" depends="clean">
        <echo>===== Testing in parallel using fork="true" =====</echo>
        <property name="fork" value="true"/>
        <parallel threadCount="3">
            <antcall target="test1"/>
            <antcall target="test2"/>
            <antcall target="test3"/>
        </parallel>
    </target>

    <target name="parallel" depends="clean">
        <echo>===== Testing in parallel using fork="false" =====</echo>
        <property name="fork" value="false"/>
        <parallel threadCount="3">
            <antcall target="test1"/>
            <antcall target="test2"/>
            <antcall target="test3"/>
        </parallel>
    </target>

    <target name="test1">
     <javac srcdir="." fork="${fork}" includes="Test1.java" debug="true" optimize="true" source="1.5" target="1.5"/>
    </target>

    <target name="test2">
     <javac srcdir="." fork="${fork}" includes="Test2.java" debug="true" optimize="true" source="1.5" target="1.5"/>
    </target>

    <target name="test3">
     <javac srcdir="." fork="${fork}" includes="Test3.java" debug="true" optimize="true" source="1.5" target="1.5"/>
    </target>
</project>

== CompilerTest.java ==

import java.io.PrintWriter;

public class CompilerTest
{
    public static void main(String[] args) throws InterruptedException
    {
        PrintWriter out = new PrintWriter(System.out);

        out.println("Testing in series\n");

        compile(args[0], out);
        compile(args[1], out);
        compile(args[2], out);

        out.println("\nTesting in parallel\n");

        Thread thread1 = new CompileThread(args[0], out);
        Thread thread2 = new CompileThread(args[1], out);
        Thread thread3 = new CompileThread(args[2], out);

        thread1.start();
        thread2.start();
        thread3.start();

        while(thread1.isAlive() || thread2.isAlive() || thread3.isAlive())
            Thread.sleep(100);

        out.close();
    }

    private static void compile(String file, PrintWriter out)
    {
        int retVal = com.sun.tools.javac.Main.compile(new String[]{file}, out);
        out.println("Return code for " + file + " = " + retVal);
    }

    private static class CompileThread extends Thread
    {
        private String _file;
        private PrintWriter _out;

        private CompileThread(String file, PrintWriter out)
        {
            _file = file;
            _out = out;
        }

        @Override
        public void run()
        {
            compile(_file, _out);
        }
    }
}

== test.cmd ==

javac -cp "%JAVA_HOME%/lib/tools.jar" CompilerTest.java
java -cp ".;%JAVA_HOME%/lib/tools.jar" CompilerTest Test1.java Test2.java Test3.java

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
1) Don't compile in parallel.
2) Compile in parallel, but fork the compiler.