RFR 8080911: sun/security/krb5/auto/UseCacheAndStoreKey.java timed out intermittently

[Weijun Wang]

On 5/26/2015 9:22 AM, Xuelei Fan wrote:
> On 5/26/2015 9:06 AM, Weijun Wang wrote:
>> On 5/26/2015 7:59 AM, Xuelei Fan wrote:
>>> synchronized on class looks a little bit unsafe to me.
>>
>> Why? Isn't it the same as making a static method synchronized? [1]
>>
> Other code may be also able to lock on class.
>
> Code 1:
> lock on MyClass.class
>
> Code 2:
> lock on MyClass.class
>
> Code 1 and 2 know nothing about each other.  The behavior may be weird.
>   I don't think it is a good practice.

So you are not a fan of all synchronized methods? :-)

I thought it's quite common to use synchronized static methods to 
prevent simultaneous access to a static field. While a method in another 
class can lock on thisClass.class (in this case the class is internal), 
I don't see why it wants to do this. This is not casual, it's just evil.

>
>>> As singleton is
>>> a static variable, creating the instance during initialization looks
>>> safer.
>>>
>>> -   private static Config singleton = null;
>>> +   private static Config singleton = new Config();
>>
>> This line might throw an exception. Also, do you intend to make
>> getInstance() simply returning singleton? This means if the first call
>> to new Config() throws an exception, getInstance() will not try to
>> reconstruct it. This might not be common in production, but I don't want
>> to make any behavior change.
>>
> I see you point.  Maybe, you can lock on a object.

A private static final Object? Yes I can, but is it worth doing?

Thanks
Max

>
> Xuelei
>
>> --Max
>>
>> [1]
>> https://docs.oracle.com/javase/specs/jls/se7/html/jls-8.html#jls-8.4.3.6
>>
>>>
>>> Xuelei
>>>
>>> On 5/25/2015 10:16 PM, Weijun Wang wrote:
>>>> Hi All
>>>>
>>>> Please review a code change at
>>>>
>>>>     http://cr.openjdk.java.net/~weijun/8080911/webrev.00/
>>>>
>>>> I've limit the synchronized block to Config creation only and therefore
>>>> won't deadlock with EType's class initialization.
>>>>
>>>> Noreg-hard. The EType call is at class initialization and only run once
>>>> in a VM session, which is extremely difficult to catch.
>>>>
>>>> Thanks
>>>> Max
>>>
>