Re: [EsiGate-devel] Webassembletool-devel Digest, Vol 2, Issue 4

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Synchronizing slows down performance unit test which fails. 
We are still investigating this solution. 

But I think that rather solving concurrent calls to this hashmap, we may prevent these call somewhere higher in the code :

If several thread are updating the same cached response, this means that we have launched at the same time several update queries  for the SAME content (url+headers). 

We may : 
 - force queries to run one after another.
 - return an old object while it is being updated. 
 - copy & replace hashmap / treeset instead of updating them.

Nicolas

Le 21 mars 2012 à 16:14, Juigne, Stephane a écrit :

> That's exactly the fix I did, but for now test fails, I'm still investigating....
> 
> Regards
> 
> -----Message d'origine-----
> De : Nicolas Richeton [mailto:nic...@gm...] 
> Envoyé : mercredi 21 mars 2012 16:13
> À : web...@li...
> Objet : Re: Webassembletool-devel Digest, Vol 2, Issue 4
> 
> Sure, I'm sending this to Stephane (watstf) so he can make the fix and send the pached package to performance environment.
> Stéphane, be sure to register to -devel list so you can reply directly :-)
> 
> Nicolas
> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Wed, 21 Mar 2012 15:23:58 +0100
>> From: Fran?ois-Xavier Bonnet 	<fra...@ce...>
>> Subject: Re: [EsiGate-devel] Thread locked under load
>> To: web...@li...
>> Message-ID: <4F6...@ce...>
>> Content-Type: text/plain; charset="iso-8859-1"
>> 
>> OK, so we should wrap the TreeSet and HashMap used in Output class using 
>> Collections.synchronizedSortedSet(...) and Collections.synchronizedMap(...)
>> Nicolas, can you check that it fixes the problem ?
>> 
>> Le 21/03/2012 15:10, Alexis Thaveau a ?crit :
>>> http://java.dzone.com/articles/concurrency-and-hashmap
>>> 
>>> Le 21/03/2012 15:08, Alexis Thaveau a ?crit :
>>>> The main bug is that headers.put is called by several threads at same 
>>>> time. As you said, thread are still runnable,  i think map is broken, 
>>>> and result is a kind of infinite loop.
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> Le 21/03/2012 14:53, Fran?ois-Xavier Bonnet a ?crit :
>>>>> This is a real problem but do you think it can explain the 100% CPU ?
>>>>> Shouldn't we have some ConcurrentModificationException ?
>>>>> Cordialement,
>>>>> 
>>>>> Fran?ois-Xavier Bonnet
>>>>> Responsable de production
>>>>> Smile - Open Source Solutions
>>>>> www.smile.fr
>>>>> T?l : +33 1 41 40 59 28
>>>>> Fax : +33 1 47 30 25 61
>>>>> GSM : +33 6 17 45 19 08
>>>>> 
>>>>> Le 21/03/2012 11:52, Alexis Thaveau a ?crit :
>>>>>> Hi,
>>>>>> 
>>>>>> Implementation of TreeSet is not synchronized => not thread safe. 
>>>>>> http://docs.oracle.com/javase/6/docs/api/java/util/TreeSet.html
>>>>>> TreeSet must be wrapped with Collections.synchronizedSortedSet || 
>>>>>> <http://docs.oracle.com/javase/6/docs/api/java/util/Collections.html#synchronizedSortedSet%28java.util.SortedSet%29>
>>>>>> 
>>>>>> 
>>>>>> Le 21/03/2012 11:44, Nicolas Richeton a ?crit :
>>>>>>> Hi all
>>>>>>> 
>>>>>>> We have an issue with with ESIGate 2.19 under load, resulting to 100% cpu usage and lock.
>>>>>>> 
>>>>>>> Please have a look to :
>>>>>>> http://sourceforge.net/apps/mantisbt/webassembletool/view.php?id=84
>>>>>>> 
>>>>>>> We have the setup show the issue, but not easy to test. Problem arises after several hours.
>>>>>>> 
>>>>>>> This seems to be linked to the new cache system because older versions of ESIGate did not show any locking under heavy load.
>>>>>>> 
>>>>>>> Andreii : any idea/comments on this issue ?
>>>>>>> 
>>>>>>> Nicolas
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>>>>>> 
>>>>>> -- 
>>>>>> Alexis Thaveau
>>>>>> Agence Nantes
>>>>>> Smile - Open Source Solutions
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>>>>>> 
>>>>>> 
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>>>> 
>>>> -- 
>>>> Alexis Thaveau
>>>> Agence Nantes
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>>> 
>>> -- 
>>> Alexis Thaveau
>>> Agence Nantes
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>>> 
>>> 
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