Request for review: Race conditions in java.nio.charset.Charset (original) (raw)

David Holmes - Sun Microsystems David.Holmes at Sun.COM
Thu Oct 8 04:35:40 UTC 2009

Ulf,

Ulf Zibis said the following on 10/08/09 08:58:

For my better understanding: Can you explain me the real bug in http://bugs.sun.com/bugdatabase/viewbug.do?bugid=6881442. In my understanding, loading the "name" field twice is too only a performance bug. Please correct me!

Class.getName() could in theory return null and this is not allowed, hence this was a functional correctness issue.

There are a few benevolent data-races in the JDK libs. I haven't looked at the Charset code so can't comment on whether or not it is benevolent.

David Holmes

I don't think it's worth a point fix here unless an actual wrong result can be demonstrated. I do think a more sophisticated charset cache would be good, but hard to get right.

The other point is the size of the cache, see http://bugs.sun.com/bugdatabase/viewbug.do?bugid=6795535. I have logged the usage of the Charset.lookup() method from a simple test which has only called ISO-8859-1 and IBM037 . As you can see, UTF-8 and cp1252 (default encoding on German Windows) is frequently requested from the VM, so IMO size 2 is too restrictive (note the different aliases UTF-8, utf-8 and UTF8): UTF-8 utf-8 UTF-8 Cp1252 UTF-8 UTF-8 UTF-8 UTF-8 UTF-8 UTF-8 UTF8 UTF8 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 Cp1252 UTF-8 IBM037 UTF-8 UTF-8 utf-8 ISO-8859-1 UTF-8 -Ulf

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