bottleneck by java.lang.Class.getAnnotations()

[Joe Darcy]

On 11/1/2012 7:11 AM, Alan Bateman wrote:
> On 01/11/2012 13:17, Alexander Knöller wrote:
>> Hi there.
>>
>> java.lang.Class.getAnnotations() always enters a synchronized-block, 
>> slowing down multi core machines that heavily make use of Annotations.
>> (in our Case we use LoadTimeWeaving in the spring-framework 3.1.2)
>> We are using sun-jdk 6 which has the same performance-bottleneck.
>> openjdk7 and 8 show no fix so far, although it looks like it might be 
>> possible to build a kind of double-checked locking?
>>
>> Has this issue ever been persued?
>>
>> Special Regards
>> Alex Knöller
>>
> If you have a proposal then I suggest bringing it to core-libs-dev for 
> discussion. In addition to contention there are other issues that need 
> attention there too, particularly the potential to deadlock and the 
> overhead per Class when annotations aren't used. There's definitely 
> some useful work that could be done there.
>
>

Note that the block in question is synchronized so that getAnnotations 
returns the right result if the class has been redefined at runtime 
using an API for that purpose.

-Joe