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= Threading issue with PJSUA initialization and shutdown =

To use PJSIP, it is recommended to call {{{pj_init()}}} and {{{pj_shutdown()}}} from the main thread. After {{{pj_init()}}} is completed, application can continue with the initialization or create a secondary/worker thread and register the thread by calling {{{pj_thread_register()}}} (Creating a secondary thread is especially recommended, sometimes necessary, for apps that require main thread to be responsive, such as GUI apps, or apps that use video, or real-time apps). As described in [http://www.pjsip.org/docs/latest/pjsip/docs/html/group__PJSUA__LIB__BASE.htm#details PJSUA-API Basic API documentation], app needs to call {{{pjsua_create()}}}, {{{pjsua_pool_create()}}}, {{{pjsua_init()}}} to perform the initialization. Then app must call {{{pjsua_start()}}} to start PJSUA and finally after everything is done, call {{{pjsua_destroy()}}} to shut it down. Sample code:

 {{{
 int main()
 {
     pj_init();
     // Continue with PJSUA initialization here or create a secondary thread
     ....
     // After pjsua_destroy() is called
     pj_shutdown();
 }

 int worker_thread()
 {
     // Register the thread, after pj_init() is called
     pj_thread_register();

     // Create pjsua and pool
     pjsua_create();
     pjsua_pool_create();

     // Init pjsua
     pjsua_init();

     // Start pjsua
     pjsua_start();

     .........

     // Destroy pjsua
     pjsua_destroy();
 }
 }}}

When restarting the library, after {{{pjsua_destroy()}}} is completed, application needs to call {{{pj_shutdown()}}} and {{{pj_init()}}} in the main thread.
Application also needs to make sure that the number of calls to {{{pj_shutdown()}}} matches with the calls to {{{pj_init()}}}

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