RFR: 7113878: LogManager - namedLoggers should be ConcurrentHashMap instead of Hashtable

[Daniel Fuchs]

On 26/03/15 14:43, Peter Levart wrote:
> On 03/26/2015 01:28 PM, David Holmes wrote:
>> Hi Daniel,
>>
>> On 26/03/2015 10:08 PM, Daniel Fuchs wrote:
>>> Please find below a trivial fix for
>>>
>>>
>>> 7113878: LogManager - namedLoggers should be ConcurrentHashMap
>>>           instead of Hashtable
>>
>> As you say in the bug report, now that the map is always accessed
>> within synchronized code this serves no purpose. The map not only
>> doesn't need to be concurrent, it doesn't even need to be thread-safe!
>> So why not replace with a simple HashMap?
>>
>> David
>
> Hi Daniel,
>
> ...or, if you keep CHM, you might be able to use it for a benefit.
>
> You say that retrieving a logger by name is the most frequent operation.
> If you can prove that moving a statement in addLocalLogger method that
> publishes the Logger via CHM to the end of synchronized block without
> hurting the logic that exists in-between and initializes the Logger
> instance, then you can implement the findLogger method in a way that
> almost never needs to enter synchronized block:
>
> http://cr.openjdk.java.net/~plevart/jdk9-dev/LogManager.CHM/webrev.01/

Right. I was also thinking that there may be a way to
use computeIfAbsent to rewrite some of the old logic - but I'd
rather do that in a separate change set.
This is partly why I didn't want to go much more beyond
the simple switch here. I'll keep your idea above in mind though.

Synchronization in LogManager is something that has always proved
to require careful thinking ;-)
Is it OK with you if I log a follow up RFE instead?

best regards

-- daniel
>
> Regards, Peter
>
>>
>>> https://bugs.openjdk.java.net/browse/JDK-7113878
>>>
>>> http://cr.openjdk.java.net/~dfuchs/webrev_7113878/webrev.00
>>>
>>> best regards,
>>>
>>> -- daniel
>