[bt-devel] Excessive CPU consumption during module install

[Greg Hellings]

Jaak,

On Tue, Jul 7, 2009 at 2:47 PM, Jaak Ristioja<Ristioja at gmail.com> wrote:
> Hi!
>
> I've been able to reproduce this with 2.0.1. Here's part of a backtrace
> for this situation:
>
> #0  0x00007fa2a733fe2c in sword::FileDesc::getFd () from
> /usr/lib/libsword-1.5.11.so
> #1  0x00007fa2a732e9cc in sword::SWConfig::Load () from
> /usr/lib/libsword-1.5.11.so
> #2  0x00007fa2a732f5e1 in sword::SWConfig::SWConfig () from
> /usr/lib/libsword-1.5.11.so
> #3  0x00007fa2a7332c3e in sword::SWMgr::loadConfigDir () from
> /usr/lib/libsword-1.5.11.so
> #4  0x00007fa2a7339fae in sword::SWMgr::Load () from
> /usr/lib/libsword-1.5.11.so
> #5  0x00000000004e6bcc in CSwordBackend::initModules ()
>
> #6  0x000000000055957e in instbackend::backend ()
>
> #7  0x0000000000560209 in BtInstallThread::BtInstallThread ()
>
> #8  0x0000000000562049 in
> BtInstallProgressDialog::BtInstallProgressDialog ()
>
> #9  0x0000000000564fea in BtSourceWidget::slotInstallAccepted ()
>
>
> It appears that the BtInstallProgressDialog constructor creates a
> BtInstallThread for every work selected to be installed. The
> BtInstallThread constructor calls instbackend::backend, which calls
> CSwordBackend::initModules(), which calls sword::SWMgr::Load(). The
> latter method takes most CPU time. Multiply that time with the number of
> works selected and you got a huge delay.

That definitely sounds like it is the source of the problem.  I'm
guessing that is done so that the download and install can be executed
in parallel.  Someone more familiar with that... is there a reason why
we can't use a single thread to do the installs while another updates
the GUI?  Is parallel downloading and installing actually what's going
on, and it is worth the performance increase?  It sure doesn't seem
that it is, to me!

--Greg

>
> Unfortunately I'm not familiar with the code, so I have been unable to
> produce a fix. I hope you'll figure this out before 2.1. :)
>
> Blessings!
> Jaak
>
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