[Kde-pim] Review Request 114341: Fix a bug in kmail that eats all cpu

[Raul Fernandes]

> On Dec. 7, 2013, 12:12 p.m., Laurent Montel wrote:
> > Do you have a trace which shows this problem ?
> > That it's call all the time ?
> > 
> > Regards

Yes.
I've profiled the kmail to see where the problem occurs.
I've saw that the QueryBuilder::exec() is called too much (and 2 functions from QueryCache class).
In a few seconds, this function is called 128.000 times.
So I put a qDebug in QueryBuilder::exec().

#else
  mStatement = statement;
#endif
  qDebug() << "QueryBuilder::exec() - Statement: " << statement;
  return true;
}

So I got the log that I upload to review.
If you do this command:

$ cat log | grep "SELECT CollectionTable.id, CollectionTable.remoteId, CollectionTable.remoteRevision, CollectionTable.name, CollectionTable.parentId, CollectionTable.resourceId, CollectionTable.subscribed, CollectionTable.cachePolicyInherit, CollectionTable.cachePolicyCheckInterval, CollectionTable.cachePolicyCacheTimeout, CollectionTable.cachePolicySyncOnDemand, CollectionTable.cachePolicyLocalParts, CollectionTable.queryString, CollectionTable.queryLanguage, CollectionTable.isVirtual FROM CollectionTable WHERE ( parentId = :0 )" | wc -l

You will get:

74972

There are 74972 statements exactly equals in a few seconds of execution.
So I see the code to find where this calls are made.
That's how I find that initFolders() is causing the bug.
To test it, I put a disconnect() in slotDefaultCollectionsChanged() and the problem disapears.


- Raul


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On Dec. 7, 2013, 11 a.m., Raul Fernandes wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/114341/
> -----------------------------------------------------------
> 
> (Updated Dec. 7, 2013, 11 a.m.)
> 
> 
> Review request for KDEPIM.
> 
> 
> Bugs: 323929
>     http://bugs.kde.org/show_bug.cgi?id=323929
> 
> 
> Repository: kdepim
> 
> 
> Description
> -------
> 
> The bug is described in https://bugs.kde.org/show_bug.cgi?id=323929.
> The bug triggers several queries to akonadi to get the same information.
> I think it is caused by the repeated connect() calls in initFolders() function (even using the Qt::UniqueConnection).
> So everytime the function slotDefaultCollectionsChanged() is called, disconnect the signal to avoid accumulate multiple signals.
> I think the right way is to rewrite the initFolders to call connect() only once.
> Split initFolders() in 2 functions. One is called by kmail and another (with the connect()) called by slotDefaultCollectionsChanged().
> For now, the disconnect() should be a good workaround for the (critical) bug.
> 
> 
> Diffs
> -----
> 
>   mailcommon/kernel/mailkernel.cpp 5b92778 
> 
> Diff: http://git.reviewboard.kde.org/r/114341/diff/
> 
> 
> Testing
> -------
> 
> Until now, it is ok here.
> 
> 
> Thanks,
> 
> Raul Fernandes
> 
>

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