Hello,

Am 21.09.2014 um 18:57 schrieb S. Razi Alavizadeh:
> Hello again,
> 
>> No, there are several search tasks running but all of their calls to the
>> DjVuLibre API are serialized, so they are not really running in parallel
>> but rather interleaved. And this is then also true for rendering which
>> is not an acceptable limitation.
> 
> 
> OK, then I think a workaround is using a threadpool with max thread count
> set to one on Windows.
> But I think for now we can leave it because there are no lots of Windows
> users. (maybe just me :D )

As a workaround, yes. But this will have the same implication that all
searching is interleaved even though if you use a different thread pool
than for rendering it will not limit the concurrency of that.

What would probably be most useful in this situation is filing a bug
report with the DjVuLibre project or at least discussing the issue on
their mailing list. (Because maybe it is an API usage error after all.)

Best regards, Adam.

> Thanks,
> Razi.
> 
> 
> 2014-09-21 20:09 GMT+03:30 Adam Reichold <email address hidden>:
> 
> Hello again,
> 
> Am 21.09.2014 um 18:29 schrieb S. Razi Alavizadeh:
>> Hello Adam,
>>
>>> your change fixes the symptom because all DjVu API access is serialize
>>> as if there was only a single thread
>>
>>
>> No, maybe I explain it badly, with changes that I pushed yesterday, search
>> works as expected, i.e. there are parallel searches started on all opened
>> document without crash.
> 
> No, there are several search tasks running but all of their calls to the
> DjVuLibre API are serialized, so they are not really running in parallel
> but rather interleaved. And this is then also true for rendering which
> is not an acceptable limitation.
> 
> Best regards, Adam.
> 
>> Best Regards,
>> Razi.
>>
>> 2014-09-21 19:33 GMT+03:30 Adam Reichold <email address hidden>:
>>
>>> Hello Razi,
>>>
>>> your change fixes the symptom because all DjVu API access is serialize
>>> as if there was only a single thread, but not the issue since the
>>> problem is most likely within the Windows of DjVuLibre as other
>>> platforms can happily render or search pages of different documents and
>>> hence contexts in parallel which is a performance improvement I would
>>> not miss because of one problematic port. My suggestion was in any case
>>> meant to isolate the problem so that we now know that the Windows
>>> implemenation of DjVuLibre has a threading problem for text extraction
>>> which the POSIX port does not seem to have. (Or our usage of the API is
>>> wrong and it works on Linux by pure luck which have no indication for so
>>> far.)
>>>
>>> Best regards, Adam.
>>>
>>> --
>>> You received this bug notification because you are subscribed to the bug
>>> report.
>>> https://bugs.launchpad.net/bugs/1370540
>>>
>>> Title:
>>>   Search within multiple DjVu files.
>>>
>>> Status in qpdfview:
>>>   Incomplete
>>>
>>> Bug description:
>>>   Steps to reproduce:
>>>   1- Open more than two DjVu that you know have the text you trying to
>>> search.
>>>   2- Write the string you want to search if search-line edit and use
>>> SHIFT+Enter to start search within all opened documents.
>>>   3- Crash!!
>>>   4- There's no problem when at most one DjVu document is opened.
>>>
>>>   Call stack from WinDbg:
>>>   ntdll!RtlpNtSetValueKey+0x12b
>>>   ntdll!RtlpNtSetValueKey+0x2914
>>>   ntdll!RtlpNtSetValueKey+0x31c5
>>>   ntdll!LdrSetAppCompatDllRedirectionCallback+0x11442
>>>   MSVCR100!free+0x1c
>>>   libdjvulibre!DJVU::GExceptionHandler::operator=+0x5e
>>>   libdjvulibre!miniobj_t::destroy+0xc
>>>   libdjvulibre!miniexp_symbol+0x564
>>>   libdjvulibre!ddjvu_document_get_outline+0x39b
>>>   libdjvulibre!ddjvu_document_get_outline+0x43d
>>>   libdjvulibre!ddjvu_document_get_outline+0x43d
>>>   libdjvulibre!ddjvu_document_get_pagetext+0x1c9
>>>   qpdfview_djvu!qt_plugin_instance+0x24b4
>>>   ntdll!RtlAllocateHeap+0xc6
>>>   QtCore4!QAbstractEventDispatcher::QAbstractEventDispatcher+0x39
>>>   qpdfview+0x18a16
>>>   QtCore4!QThread::setPriority+0x3a3
>>>   QtCore4!QString::toStdWString+0x1b3b
>>>   MSVCR100!endthreadex+0xe4
>>>   ntdll!RtlCreateMemoryZone+0x9b
>>>   ntdll!RtlCaptureContext+0xeb
>>>
>>> To manage notifications about this bug go to:
>>> https://bugs.launchpad.net/qpdfview/+bug/1370540/+subscriptions
>>>
>>
>>
> 
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1370540
> 
> Title:
>   Search within multiple DjVu files.
> 
> Status in qpdfview:
>   Incomplete
> 
> Bug description:
>   Steps to reproduce:
>   1- Open more than two DjVu that you know have the text you trying to
> search.
>   2- Write the string you want to search if search-line edit and use
> SHIFT+Enter to start search within all opened documents.
>   3- Crash!!
>   4- There's no problem when at most one DjVu document is opened.
> 
>   Call stack from WinDbg:
>   ntdll!RtlpNtSetValueKey+0x12b
>   ntdll!RtlpNtSetValueKey+0x2914
>   ntdll!RtlpNtSetValueKey+0x31c5
>   ntdll!LdrSetAppCompatDllRedirectionCallback+0x11442
>   MSVCR100!free+0x1c
>   libdjvulibre!DJVU::GExceptionHandler::operator=+0x5e
>   libdjvulibre!miniobj_t::destroy+0xc
>   libdjvulibre!miniexp_symbol+0x564
>   libdjvulibre!ddjvu_document_get_outline+0x39b
>   libdjvulibre!ddjvu_document_get_outline+0x43d
>   libdjvulibre!ddjvu_document_get_outline+0x43d
>   libdjvulibre!ddjvu_document_get_pagetext+0x1c9
>   qpdfview_djvu!qt_plugin_instance+0x24b4
>   ntdll!RtlAllocateHeap+0xc6
>   QtCore4!QAbstractEventDispatcher::QAbstractEventDispatcher+0x39
>   qpdfview+0x18a16
>   QtCore4!QThread::setPriority+0x3a3
>   QtCore4!QString::toStdWString+0x1b3b
>   MSVCR100!endthreadex+0xe4
>   ntdll!RtlCreateMemoryZone+0x9b
>   ntdll!RtlCaptureContext+0xeb
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qpdfview/+bug/1370540/+subscriptions
> 
> 
>