RFR(M) 8242165: SA sysprops support fails to dump all system properties

[Chris Plummer]

Hi Yasumasa,

On 4/5/20 11:56 PM, Yasumasa Suenaga wrote:
> Hi Chris,
>
> On 2020/04/06 15:46, Chris Plummer wrote:
>> Hi Yasumasa,
>>
>> I'm not sure what you mean by "conflict some keys". Can you explain?
>
> System properties stores in ConcurrentHashMap. `next` field would be 
> used when hashcode of key string is conflicted.
Yes, but are referring to how System Properties are stored, which is 
determined by the implementation of java.lang.System. SA cannot control 
that, but it must mimic the java.lang.System implementation. That means 
when SA fetches the System::_props field, it needs to know what type of 
data structure it points to. It thought it pointed to a hash table that 
used a rehash function (which maybe it did at one point), but it 
actually points to a hash table that uses chains (link lists) instead of 
rehashing.
> I think it would be better if we can add key strings which are 
> different and have same hashcode.
That's what it does. The property Nodes are chained when more than one 
property hashes to the same hast table index. The problem was that SA 
didn't realize they were chained so only saw the first property in the 
chain.

thanks,

Chris
>
>
> Thanks,
>
> Yasumasa
>
>
>> thanks,
>>
>> Chris
>>
>> On 4/5/20 11:41 PM, Yasumasa Suenaga wrote:
>>> Hi Chris,
>>>
>>> Almost your change looks good, but I have a question in 
>>> TestSysProps.java.
>>> Can we conflict some keys in sysprops always? It is better if we can 
>>> do so, but it is very difficult.
>>>
>>>
>>> Thanks,
>>>
>>> Yasumasa
>>>
>>>
>>> On 2020/04/06 14:49, Chris Plummer wrote:
>>>> Hello,
>>>>
>>>> Please help review the following:
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-8242165
>>>> http://cr.openjdk.java.net/~cjplummer/8242165/webrev.03
>>>>
>>>> Please see the CR for an explanation of the bug and the fix. If you 
>>>> need some help with the SA code, let me know and I'll provide some 
>>>> details. It was pretty much all new to me, so I tried to put the 
>>>> needed details in the CR.
>>>>
>>>> For the test, I compare the list of properties dumped using 3 
>>>> different methods to make sure the same set is dumped for each:
>>>>
>>>> 1. jhsdb jinfo --sysprops
>>>> 2. jinfo -sysprops
>>>> 3. Simple app (LingeredAppSysProps) that calls 
>>>> System.getProperties().list(System.out)
>>>>
>>>> The app output is considered the master list that is compared 
>>>> against the others, and I also make sure each list has the same 
>>>> number of properties.
>>>>
>>>> thanks,
>>>>
>>>> Chris
>>