Robert Burrell Donkin ha scritto:
> On 8/9/07, Stefano Bagnara <[EMAIL PROTECTED]> wrote:
>> Bernd Fondermann ha scritto:
>>> What types of exceptions do you get? NPE?
>>>
>>> if it wasn't for a ThreadLocal, I'd say that this method's init is not
>>> atomic, if fieldInstance is NULL:
>>>
>>> static protected void setInstance(CommandStateManager conditionManager)
>>> {
>>> if (null == fieldInstance)
>>> fieldInstance = new ThreadLocal();
>>> fieldInstance.set(conditionManager);
>>> }
>>>
>>> It leaves ThreadLocal uninitialized but accessible for a little
>>> moment. if the method got interrupted in between and getInstance()
>>> gets executed, this might result in a NPE.
>> Good catch!!
>
> +1
>
> not sure that it's possible to create a good test for this but
> https://issues.apache.org/jira/browse/JSIEVE-10 demonstrates that it
> occurs in the wild. unless someone jumps in with a good idea for a
> test, i'll commit a fix without a test.
>
> - robert
Go ahead: I don't think a test can be written for similar racing
conditions as there is no way to control 2 threads in order to have them
executing that code with the specific timing needed to show the problem.
Stefano
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