PLplot is not threadsafe. When run with PThreads, it can be made to produce bad output. I've attached a simple script that creates said bad output. The solution is to add the NoPThreads flag to the PLplot bindings.
A script that causes PLplot trouble.
Example of output with PThreads disabled.
Example of bad output with PThreads enabled.
Output of pdl -V
Marking this as critical as it is a showstopper for PLplot users
and the new multicore support feature.
Bug fixed in Git.
Thanks for reporting the problem!
I have submitted something that I believe solves the problem in the latest git repo. I cannot test it, however, Somebody who has PLplot installed needs to confirm that the update does indeed solve the problem.