added lock around run... may not be needed in the future, only relevant when multiple threads use 1 execution object
added lock around run... may not be needed in the future, only relevant when multiple threads use 1 execution object

maartenbreddels/vaex,maartenbreddels/vaex,maartenbreddels/vaex,maartenbreddels/vaex,maartenbreddels/vaex,maartenbreddels/vaex