However certain rules and restrictions apply. Theses rules are confusing as they have been changing from one version of the library to another and the documentation wasn't and still isn't very clear about them. Documentation pages often display notes like: "Deprecated since..." or "DRAFT IN PROGRESS...", or "Not Found 404".
Starting in Gecko 12.0 or SpiderMonkey 24, the rules are:
You may consider building a debug version of SpiderMonkey to test your integration. Try using flags:
--enable-root-analysis --enable-debug --disable-optimize
Those add assertions in the library code to help catching thread (garbage collector, and memory) related problems earlier.