普通线程中调用bthread_start_background100次，在函数中打印对应的stack 100次执行的都是一个值，对应的cur_tid都是0，我打印前是取出来对应的值赋值局部变量打印的

并且打印的is_main_task都是true，这种是什么情况呢，这是在同一个bthread中执行的？

Start with the bthread_start_background call path and reproduce the reported 100-call case from an ordinary thread. Trace how cur_tid and is_main_task are obtained inside the started function, then establish whether the calls share a bthread or why the printed values are identical; done means the behavior is explained and any required correction is covered by a reproducible check.

Written by the indexing model from the issue text.