c++ - pthread_join() fail on ios -

i working on multithread project on ios. in project pthread joining failing sometime.

pthread_join(thread_id, null) == 0 

note: occurring on ios , random. can reason failing join operation.

man page says:

errors pthread_join() fail if:

 [edeadlk]          deadlock detected or value of thread speci-                     fies calling thread.   [einval]           implementation has detected value speci-                     fied thread not refer joinable thread.   [esrch]            no thread found corresponding speci-                     fied given thread id, thread.