FULL PRODUCT VERSION :
java version "1.5.0_05"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_05-b05)
Java HotSpot(TM) Client VM (build 1.5.0_05-b05, mixed mode, sharing)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows 2000 [Version 5.00.2195]

A DESCRIPTION OF THE PROBLEM :
any pattern like (x|y)* (an alternative wrapped in a star) is implemented recursively by Pattern. Each matched alternative uses about 5 method calls on the stack.

This makes that kind of pattern useless on any reasonably-sized input. Is there any chance you can make the Pattern implementation non-recursive in this case?

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
see example code

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
matched? true
ACTUAL -
java.lang.StackOverflowError

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.StackOverflowError
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
at java.util.regex.Pattern$Single.match(Pattern.java:3004)
at java.util.regex.Pattern$Branch.match(Pattern.java:3933)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:3973)
at java.util.regex.Pattern$Loop.match(Pattern.java:4100)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4032)
Exception in thread "main"


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class RegexpFun {
    public static void main(String[] args) {

        CharSequence largeString = makeLargeString();
        Pattern p = Pattern.compile("(x|y)*");
        Matcher m = p.matcher(largeString);
        System.out.println("matches? " + m.matches()); // throws StackOverflowError
    }

    private static CharSequence makeLargeString() {
        final int size = 1000;
        StringBuffer largeString = new StringBuffer(size);
        for (int i = 0; i < size/2; i++) {
            largeString.append("xy");
        }
        return largeString;
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
no workaround