I.) Internal charset cache will be corrupted in theoretical race conditions:
Startpoint:
cache1 --> Charset1
cache2 --> Charset2
Scenario 1:
- Thread1 asks for Charset2 via Charset.forName("Charset2").
- If Thread1 is interrupted after code line: cache2 = cache1
in method lookup2(String charsetName) we have:
cache1 --> Charset1
cache2 --> Charset1
If now thread2 asks for Charset2, it can't find it in cache, so it invokes
an expensive lookup via registered providers.
Scenario 2:
- Thread1 asks for Charset2.
- Thread1 is interupted before cache2 = cache1;
- If now thread2 asks for Charset2 we have after completing lookup2():
cache1 --> Charset2
cache2 --> Charset1
- Now thread1 resumes; after completing lookup2() we have:
cache1 --> Charset2
cache2 --> Charset2
In the end we can see, that Charset1 is lost in cache.
II.) Endless loop, if VM's default charset (called by Charset.defaultCharset())
needs to load mapping data via Class.getResourceAsStream():
- Invoking Class.getResourceAsStream(), again calls for
Charset.defaultCharset(),
so we are in endless loop.
Note: The error condition, described in
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6795536
is fixed since Bug ID 6797688, but the endless loop, getting the default
charset, remains.
See my patches here: https://bugs.openjdk.java.net/show_bug.cgi?id=100107
-Ulf
