Avoid sharing script objects or script arrays across threads (this includes global.) Sharing script objects is asking for trouble. Share only primitive data types, or Java objects.
N. Repčić, I. Šarić, and V. Avdić. Proceedings of the 16th International Research/Expert Conference „Trends in the Development of Machinery and Associated Technology” TMT 2012, page 511-514. Dubai, United Arab Emirates, (2012)