I have finally decided to solve my problem in a different way. I chopped up pymc source code to pieces in a way that segmented the calculations. At first, prior samples are generated and written to txt files as inputs for external software, which has the role of the simulator → all of these inputs are calculated parallely by the external software → then a different python input collects the simulator results, does the resampling, mutation, and writes proposal in txt file as inputs for external software → inputs are calculated parallely by the external software → the cycle is repeated until the end of the computations. This gives both the possibility to restart caculations from any point and to parallelize calculations on a cluster.
Cheers!