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Re: [Plplot-devel] setlocale
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From: Hazen B. <hba...@ma...> - 2023-06-13 12:32:02
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Hi Phil, I don't think (1) is a good idea. It seems like this only effects somewhat extreme plotting situations? Some of the examples also use plshade() and they don't seem to be particularly slow. Alan I think was concerned that the libraries that come with a driver might change the locale. The cairo driver for example has a rather large library behind it. This library might not change the locale, but it would be hard to be sure, and this might change as the library changes. Also it seems that the overhead of setting and restoring the locale would affect any situation with a complicated plot, perhaps most easily created using plshades, but if you tried to dray 1M lines you might see something similar? So perhaps there are some optimizations that could be made instead? For example we could check if the locale was already "C" before setting it to "C" and then restoring? We could change saved_lc_numerical_locale to a static variable (and not free it in plrestore_locale) to reduce the amount of memory churn? We could add a compiler flag that makes plsave_set_locale() and plrestore_locale() into nops for those who are okay with this? best, -Hazen On 6/2/23 05:55, Phil Rosenberg wrote: > Hi Hazen, Arjen > Thanks for the detective work - Alan has used that feature to help me in > the past and I had totally forgotten about it. > > I can see Alan's intention here. In the wxWidgets driver I did similar > things with other properties. For example I ensure the device context > pen and brush are always set and reset during calls to the driver. This > is so that if the user draws to the device context between calls, then > plPlot does not cause problems for the user and visa-versa. > > Setting and resetting the brush was also an expensive operation, so to > avoid those calls I have added an escape for starting and stopping > plshade. I know that between these escapes there is no need to worry > about setting and restoring the state. > > I think there are a few options, from most intrusive to least intrusive. > 1. Undo Alan's work and make it the responsibility of the driver to > restore the locale. This is what wxWidgets does with device context brushes. > 2. Find where we think the locale might need saving and restoring and > only do it for these calls. I'm not sure I like this, as it makes > responsibility a grey area. Also I just tried 'ack locale' and 'ack > LC_NUMERIC in the src directory and found references only in plargs.c, > plcore.c and plctrl.c. So I don't think any drivers do actually change > the locale. > 3. I can add a variable to the PLStream which records when we enter and > leave a plshade call. This can be checked during plfill calls so that > only direct plfill calls save and restore the locale. > > My preference is for 1 or 3, does anyone else have a preference or other > thought? 3 is certainly an easier change, but I'm happy to go down > another route if people think it will be an improvement. > > Just to give an idea of the overall benefits here. I'm plotting data on > a grid with millions of points. The wxWidgets driver changes I mentioned > above and the removal of the locale save/restore and the changes I > mentioned a few weeks ago with buffer memory, mean that instead of > giving up after plPlot had been rendering for a few hours, the plot is > rendered in under 2 minutes. So that's around two orders of magnitude > speed increase at least. > > Phil > ------------------------------------------------------------------------ > *From:* Arjen Markus <Arj...@de...> > *Sent:* Friday, June 2, 2023 7:47:08 AM > *To:* Hazen Babcock <hba...@ma...>; > plp...@li... <plp...@li...> > *Subject:* Re: [Plplot-devel] setlocale > Hi Hazen, Phil, > > If the setting and restoring of the locale takes so much time, then > would it be an option to use this only on the plot functions that might > actually be affected by the locale? I have only glanced at the code and > I have no idea how much work it would be. That would preserve the > intended functionality though and get rid of the performance issue. > > Regards, > > Arjen > > -----Original Message----- > From: Hazen Babcock via Plplot-devel <plp...@li...> > Sent: Thursday, June 1, 2023 12:57 AM > To: plp...@li... > Subject: Re: [Plplot-devel] setlocale > > Caution: This message was sent from outside of Deltares. Please do not > click links or open attachments unless you recognize the source of this > email and know the content is safe. Please report all suspicious emails > to "Ser...@de..." as an attachment. > > > Github has an interesting feature which lets you browse the code and see > the last commit that touched a particular part of the code. Using that > it looks like saving and restoring the locale was added to the functions > in src/plcore.c by Alan on Sep 7, 2009. > > The commit message: > """ > Protect all device driver calls using the (now) reentrant plsave_set_... > ...locale > > and plrestore_locale. The former saves the fundamental PLplot LC_NUMERIC > locale and then sets the LC_NUMERIC locale to "C" for everything done by > all device drivers. Of course, any library called by a device driver > can also change the locale, but we guard against such changes affecting > the rest of PLplot by using plrestore_locale to restore the fundamental > PLplot LC_NUMERIC locale saved by plsave_set_locale. > > N.B. this logic allows the fundamental PLplot LC_NUMERIC locale (except > for the parts like the device drivers and palette file reading that are > protected by the combination of plsave_set_locale and plrestore_locale) > to be any valid locale set by any application or library that calls the > PLplot library. If that locale specifies comma decimal separators > rather than period decimal separators, for example, then the PLplot core > will automatically use those for for specifying axis labels. Those > commas for axis labels are drawn by the PLplot core for the Hershey font > device drivers or just propagate to the unicode device drivers as UCS4 > arrays. Thus, in both cases, we get a comma decimal separator for axis > labels (if that is what the fundamental PLplot LC_NUMERIC locale calls > for) independently of the logic of the present commit that sets the > LC_NUMERIC locale to "C" for all device driver code that is executed. > > > svn path=/trunk/; revision=10383 > """ > > -Hazen > > On 5/31/23 10:56, Phil Rosenberg wrote: > > Sorry, I was wrong in my last email - removing the locale calls from > plP_state as well (used to reset the width after a contour draw within > plshade) I ended up with a 2.5 times speed increase > > Phil > > On > Mon, 29 May 2023 at 00:38, Phil Rosenberg <p.d...@gm... > <mailto:p.d...@gm... <mailto:p.d...@gm...>>> wrote: > > > > Hi all > > I have been making further optimisations to the wxwidgets backen, as > > I have still been finding it painfully slow for plshade calls. > > It turned out that almost all the time within the backend (>99%) was > > spent selecting pens and brushes and allocating memory for every > > fill within the plshade call. Less that 1% was actually spent within > > the rendering call to wxWidgets. I have made some good improvements > > here. > > > > However, in addition to this, about 50% of the total execution time > > is spent in the setlocale function. This is called before and after > > each polygon fill in the core plplot code. > > > > I wondered if anyone really knows the purpose of these calls? > > Perhaps they are to ensure we have consistent numeric > > representations across regions? If so, then I don't really > > understand why they are needed for polygon fills. > > > > Any thoughts would be welcome > > Phil > > > > > > > > _______________________________________________ > > Plplot-devel mailing list > > Plp...@li... > > https://lists.sourceforge.net/lists/listinfo/plplot-devel > <https://lists.sourceforge.net/lists/listinfo/plplot-devel> > > > > On 5/31/23 10:56, Phil Rosenberg wrote: >> Sorry, I was wrong in my last email - removing the locale calls from >> plP_state as well (used to reset the width after a contour draw within >> plshade) I ended up with a 2.5 times speed increase >> >> Phil >> >> On Mon, 29 May 2023 at 00:38, Phil Rosenberg <p.d...@gm... >> <mailto:p.d...@gm... <mailto:p.d...@gm...>>> wrote: >> >> Hi all >> I have been making further optimisations to the wxwidgets backen, as >> I have still been finding it painfully slow for plshade calls. >> It turned out that almost all the time within the backend (>99%) was >> spent selecting pens and brushes and allocating memory for every >> fill within the plshade call. Less that 1% was actually spent within >> the rendering call to wxWidgets. I have made some good improvements >> here. >> >> However, in addition to this, about 50% of the total execution time >> is spent in the setlocale function. This is called before and after >> each polygon fill in the core plplot code. >> >> I wondered if anyone really knows the purpose of these calls? >> Perhaps they are to ensure we have consistent numeric >> representations across regions? If so, then I don't really >> understand why they are needed for polygon fills. >> >> Any thoughts would be welcome >> Phil >> >> >> >> _______________________________________________ >> Plplot-devel mailing list >> Plp...@li... >> https://list/ <https://list/> >> s.sourceforge.net%2Flists%2Flistinfo%2Fplplot-devel&data=05%7C01%7Carj >> en.markus%40deltares.nl%7C44980f7a89174ac2fd6a08db622a585a%7C15f3fe0ed >> 7124981bc7cfe949af215bb%7C0%7C0%7C638211706231092344%7CUnknown%7CTWFpb >> GZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0 >> %3D%7C3000%7C%7C%7C&sdata=%2FhX%2F5cUnr67tJIMuLcD1eZgofgKQONlnSgYD4QIb >> 7gY%3D&reserved=0 > > > > _______________________________________________ > Plplot-devel mailing list > Plp...@li... > https://lists.sourceforge.net/lists/listinfo/plplot-devel > <https://lists.sourceforge.net/lists/listinfo/plplot-devel> > DISCLAIMER: This message is intended exclusively for the addressee(s) > and may contain confidential and privileged information. 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