PROBLEM:
 On Multi-processor environment (linux), the attached sample code(A.java)
 outputs the attached exception strace.


TEST PROGRAM:
==== A.java ===
public class A {
    public static void main(String arg[]) throws Exception {
Thread t1 = new Test();
Thread t2 = new Test();

t1.start();
t2.start();
    }

    static class Test extends Thread {
public void run() {
while (!interrupted()) {
try {
"a".getBytes("ASCII");
"a".getBytes("EUC-JP-LINUX");
} catch (Exception e) {
e.printStackTrace();
}
}
}
    }
}
===============

LOG DATA:
==== log ===
java.lang.Error: java.nio.charset.UnsupportedCharsetException: EUC-JP-LINUX
        at java.lang.StringCoding.lookupCharset(StringCoding.java:84)
        at java.lang.StringCoding.encode(StringCoding.java:361)
        at java.lang.StringCoding.encode(StringCoding.java:378)
        at java.lang.String.getBytes(String.java:608)
        at java.io.UnixFileSystem.canonicalize(Native Method)
        at java.io.File.getCanonicalPath(File.java:513)
        at java.io.FilePermission$1.run(FilePermission.java:209)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.io.FilePermission.init(FilePermission.java:203)
        at java.io.FilePermission.<init>(FilePermission.java:253)
        at sun.net.www.protocol.file.FileURLConnection.getPermission(FileURLConn
ection.java:193)
        at sun.net.www.protocol.jar.JarFileFactory.getPermission(JarFileFactory.
java:111)
        at sun.net.www.protocol.jar.JarFileFactory.getCachedJarFile(JarFileFacto
ry.java:81)
        at sun.net.www.protocol.jar.JarFileFactory.get(JarFileFactory.java:50)
        at sun.net.www.protocol.jar.JarURLConnection.connect(JarURLConnection.ja
va:85)
        at sun.net.www.protocol.jar.JarURLConnection.getInputStream(JarURLConnec
tion.java:105)
        at java.net.URL.openStream(URL.java:960)
        at sun.misc.Service.parse(Service.java:203)
        at sun.misc.Service.access$100(Service.java:111)
        at sun.misc.Service$LazyIterator.hasNext(Service.java:257)
        at java.nio.charset.Charset$1.getNext(Charset.java:301)
        at java.nio.charset.Charset$1.hasNext(Charset.java:316)
        at java.nio.charset.Charset$2.run(Charset.java:359)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.nio.charset.Charset.lookupViaProviders(Charset.java:356)
        at java.nio.charset.Charset.lookup(Charset.java:383)
        at java.nio.charset.Charset.isSupported(Charset.java:405)
        at java.lang.StringCoding.lookupCharset(StringCoding.java:80)
        at java.lang.StringCoding.encode(StringCoding.java:361)
        at java.lang.String.getBytes(String.java:591)
        at A$Test.run(A.java:27)
Caused by: java.nio.charset.UnsupportedCharsetException: EUC-JP-LINUX
        at java.nio.charset.Charset.forName(Charset.java:428)
        at java.lang.StringCoding.lookupCharset(StringCoding.java:82)
        ... 30 more
============


CONFIGRATION:
 
 - MPU: Pentium III 800MHz X 2
 - OS : Turbo Linux 8 (kernel 2.4.18-5smp)
 - JRE: JDK1.4.1_01, 1.4.2(b15)


REPORT:
 
They suspect this is caused when several threads tried to modify the cache
in Charset.
Specifically speaking, java.nio.Charset#isSupported and java.nio.Charset#forName
should be atomic, but they are not.

The followings are the possible senario. Thread-A, B are created in the
test program.

Thread-A Cache Thread-B
-------- ------- ---------
  
              ASCII
    
   (1)
                              (2)
             EUC-JP-LINUX
   (3)
                              (4)
               ASCII
   (5)


(1) In thread-A, "a".getBytes("EUC-JP-LINUX") runs as follows.

  "a".getBytes("EUC-JP-LINUX")
     -> StringCoding#lookupCharset
      -> Charset#isSupported("EUC-JP-LINUX")
       -> Charset#lookup("EUC-JP-LINUX")
  
  At this stage, Charset.cache is "ASCII", cache-miss occurs and
  calls Charset#lookupViaProviders.

(2) A sequence of "a".getBytes("EUC-JP-LINUX") finishes in threda-B.
    Here, Cache is set to "EUC-JP-LINUX".

(3) During the execution in (1), StringCoding#lookupCharset is called.
    (This is from the information in the above log.)
    In lookupCharset, Charset#isSupported("EUC-JP-LINUX") is called again
    and returns true because of cahce-hit (cahche is set to "EUC-JP-LINUX"
    at (2))

(4) A sequence of "a".getBytes("ASCII") finishes.
    Here, Cache is set to "ASCII".

(5) Charset#forName("EUC-JP-LINUX") is called after
    Charset#isSupported("EUC-JP-LINUX") at (3).
    Here, cache-miss occurs and Charset#lookupViaProviders is called.
    However, lookupViaProviders is not re-entrant and returns null.
    As the result, UnsupportedCharsetException seems to happen.

===========================================================================