> > I checked how much extra CPU was used if the sleep was reduced from 100ms to
> > 20ms.  I found that when a sequence was not running the CPU increased from 0% to
> > 0.2% with my change.  When a sequence was running the CPU increased from 0.8% to
> > 4% with my change.  4% is a little high, though I'd say still reasonable.  I
> > found that most of the CPU usage was occuring because every call to
> > 'sequencer()' resulted in a call to db_set_record("/Sequencer/State"...).  I
> > guess that making that call 50 times causes the somewhat heavy CPU usage.
> > 
> > I would argue that it would still be worth making that change, so that the
> > sequencer can be more zippy.
> 
> The minimal time slice on most systems is 10 ms, and nothing prevents us from switching to
> that. The original 100 ms was more for the fact that you can see the sequencer statements
> executed one after the other (with the color bar). But this is more a "debugging" feature which 
> we not really need. 

OK, I made this change; sleep is now 10ms on main thread.  Seems to work fine on SL6 and MacOS.

> To do it "right" the sequencer would have to _return_ a sleep time. Like if it is in a wait loop (as
> most of the time), the sleep time could be close to 1 second, to correctly update the wait
> progress bar. If the sequencer executes ODB set statements, the wait time could be zero, so
> thousands of statements can be executed in one second. The problem we will then have of course
> that the sequencer will block the "request_mutex" almost always, which would prevent the
> mongoose server from serving anything. So this should be carefully tested. It could be (on most OS)
> that releasing the mutex by the main loop immediately switches to the mongoose thread, which would
> make the web server still quite responsive, but I'm not sure about that. So as a first change making
> the sleep time 10ms should be fine.

Hmm, yeah, I'm not sure about how to handle reducing the wait time to zero after ODB set commands.

But it does seem like it would be straight-forward to increase the sleep time for waits; I'll look into
a clean way of doing that.