serial ports, threads and windows

[H J van Rooyen]

 "Tom Brown" <brown at esteem.com>


| Hey people,
|
| I've written a python app that r/w eight serial ports to control eight devices
| using eight threads. This all works very nicely in Linux. I even put a GUI on
| it using PyQt4. Still works nicely.
|
| Then I put the app on on a virtual Windows machine running inside of vmware on
| the same Linux box.  Vmware only lets me have four serial ports so I run the
| app against four serial ports using four threads. The app did not respond
| quick enough to data from the serial ports and eventually hung.
|
| So, I tried one serial port and the app still did not respond quick enough to
| the single serial port. It eventually hangs.
|
| When the app hung, in each case, it was not hogging the cpu nor reading any
| data off the serial ports. The task manager didn't show it was doing anything
| at all.
|
| When it runs on Windows, could it be:
|
| 1) Just struggling to run inside of VMware?
|
| 2) Using threads with Qt on Windows is a problem?
|
| 3) Threads in python on Windows is a problem?
|
| Any ideas?
|
| Thanks,
| Tom

I cant help you really, but I can put what little weight I have behind you - I
am also struggling with serial port implementation - I posted here some time ago
and got some answers - and my intermittent failure is now down to about once a
week.

I found that while python's file handling and the GUI stuff works seamlessly
across platforms, the serial port handling seems quirky and platform dependant :

It is extraordinarly difficult to write non blocking reads that will work 'out
of the box' across platforms - in fact I dont know if it is possible..

And making a pipe non blocking is poison...

- Hendrik