Tcl was born three years earlier. The AOLServer, which was heavily multithreaded and based on Tcl, was developed in 1995: https://en.wikipedia.org/wiki/AOLserv

Tcl was born three years earlier. The AOLServer, which was heavily multithreaded and based on Tcl, was developed in 1995: https://en.wikipedia.org/wiki/AOLserver https://en.wikipedia.org/wiki/AOLserver You also can easily guess who of these two get i18n right earlier. The AOLServer was made possible by the decisions to have an API to have specific versions of interpreters (including highly constrained safe ones), by forcing extensions to have per-interpreter state and make interpreters communicate by messaging on Tcl level. This resulted that if your extension worked with several interpreters in single thread execution, it would work with several threads ruunning in parallel. The same is for just Tcl code, which does not even know which thread it gets executed on. Thus, Python developers did not do any looking around.