[Lazarus] Synchronize problem in linux

Giuliano Colla giuliano.colla at fastwebnet.it
Wed May 25 15:03:13 CEST 2011


michael.vancanneyt at wisa.be ha scritto:
>
>
> On Wed, 25 May 2011, Giuliano Colla wrote:
>
>> michael.vancanneyt at wisa.be ha scritto:
>>>
>>>
>>> On Wed, 25 May 2011, Vincent Snijders wrote:
>>>
>>>> 2011/5/25  <michael.vancanneyt at wisa.be>:
>>>>>>> No. You should use a TMultiReadExclusiveWriteSynchronizer object to
>>>>>>> synchronize access to your object, or use a critical section.
>>>>>>
>>>>>> Ehm, he made sure that only one thread accesses the TStringList at a
>>>>>> time.
>>>>>
>>>>> To me, this is not obvious from his mail ?
>>>>
>>>> I thought it was obvious from:
>>>> "The logic of the application itself made it sure that there was no
>>>> conflict whatsoever. "
>>>>
>>>> But maybe that was not not what Giuliano meant by "no conflict".
>>>
>>> This is what was not clear to me...
>>>
>>> If no conflict can mean 'it adds only', then there is a conflict at 
>>> a lower
>>> level, because adding can mean a reallocation of the array of strings.
>>>
>> The full picture is:
>> 1) The main thread creates the String List, and doesn't touch it any 
>> more.
>> 2) The other thread is activated and it is the only one which appends 
>> strings to the list.
>> 3) When the other thread is terminated, the main thread processes the 
>> list.
>>
>> I would expect that whatever activity occurs as an effect of 
>> appending strings (such as reallocating the array) would occur in the 
>> context of the thread performing the action, that all pertinent 
>> information is stored in fields of the object itself, and that the 
>> main thread is never involved.  Am I wrong on this aspect?
>
> No, you are right. If it is designed as described above, then it should
> work.
>
Thank you. With Kylix it didn't work, but there was no mailing list to 
ask :'( .
Now I'm going to develop something similar with Lazarus, and I felt it 
wise to ask, before bumping my head again against a brick wall.
 
Giuliano




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