Re: [Plplot-devel] --with-pthreads: Use pthreads with the xwin driver!

[<jc...@fe...>]

On Wednesday 05 March 2003 00:06, Joao Cardoso wrote:
| Hi,
|
| The xwin driver has been plagued for ages with a severe problem:
| whenever the user program goes to lengthly calculations, without
| doing any calls to PLplot, the plot window couldn't be refreshed if
| obscured by other windows. Nor resized.
|
| You can quickly watch this behavior if you insert a getchar()
| statement just before plend() in x01c.c. The getchar() call simulates
| the user program doing other jobs and not calling any plplot API. If
| you now obscure the plot window you will see that it is not redrawn
| (of course).
|
| This behaviour is most inconvenient for interactive languages like
| Octave or python, where the same behaviour is observed while the user
| is typing commands at the prompt.
|
| The obvious solution would be to write a xwin server or daemon, like
| the tk driver plserver, but that means a lot of work. Instead, I have
| implemented, and cvs commit, a threaded xwin driver. It updates and
| resizes the plot window, if needed.
|
| This feature is disabled by default at configure time.
|
| For most compiled programs, it can be safely turned on, even if the
| host program is not threads aware.
| For already build programs that somehow use PLplot, usually loading
| it as an extension, as Octave or python or tk does, things are a bit
| complicated, as those programs must themself be linked with the
| pthread library, even if not thread aware!
|
| For example, in my system Octave is build by default without being
| linked with pthreads, because Octave is not threads aware. To use the
| new threads enabled xwin driver, I have to *relink* (only) octave
| with -lpthread, and after that all goes well.
|
| Python, by contrary, is already linked with the pthreads library, so
| nothing special needs to be done -- the threads enabled xwin driver
| works without a problem with python.
|
| This is the reason why --with-pthreads=no by default, and should not
| be turned on.

Perhaps in a future development it will be enabled  by default at 
configure time but disabled by default at run-time. To enable it at 
run-time one could use a driver-specific option, like -drvopt pthreads.
This would be the best of both words.

Joao