Hi Yemin,

is your tests open-source? Can you send me / create a gist / put it on 
github? That we I can try to understand what is going on.

Thanks


Am Donnerstag, 5. Mai 2016 01:19:49 UTC+2 schrieb Yemin:
>
> Hi Frank,
>   I use the java driver from ArangoDB and the network link is persistent. 
> Maybe because the collection locker? In my test case, all clients are 
> writing same collection.
>
>   
> On Wednesday, May 4, 2016 at 11:42:42 PM UTC+8, Frank Celler wrote:
>>
>> Hi Yemin,
>>
>> what kind of tests are used in the YCSB? Are you using the Java driver 
>> from ArangoDB or direct HTTP requests? Sometimes I have seen, that in 
>> various languages HTTP are not persistent (by default or at all). Could you 
>> see during your test, if there are persistent HTTP connections or not? 
>>
>> A dispatcher thread keeps active for a few milli-seconds, before waiting 
>> on a condition variable. This gives better performance on some systems 
>> comapred to directly going to sleep.
>>
>> Best
>>
>>
>> Am Mittwoch, 4. Mai 2016 17:17:17 UTC+2 schrieb Yemin:
>>>
>>> Hi, recently I'm doing perf test of ArangoDB using YCSB and found 
>>> the dispatcher threads problems.
>>> Case: pure inserting operations, measuring throughput. 10 scheduler 
>>> threads, 48 clients.
>>> For throughput and total CPU cost of dispatcher threads, one dispatcher 
>>> thread has no difference with multiple dispatcher threads. It looks like 
>>> there is some kind of "global lock".
>>> Questions:
>>> 1. Why the throughput wasn't improved by adding more dispatcher threads.
>>> 2. We found many nanosleeps in dispatcher thread, maybe it's one of 
>>> reasons? And why using nanosleep instead of wait-signal?
>>>
>>> Thx!
>>>
>>

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