Below issue has been resolved. Root cause was related to timing issue. Overall the library works great to receive pulses
, fd data, ipc messages through one single blocking API.

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> Hello all,
> 
> Is their a mechanism to have a thread block on PPS file descriptors and QNX 
> IPC ( Message/Pulses )? My thread is not a resource manager.
> 
> I tried using dispatch library mechanism.
> 
> dispatch_create
> select_attach
> pulse_attach
> dipatch_context_alloc
> message_connect
> dispatch_block
> dispatch_handler
> 
> dispatch_block does not unblock with pulses. I am sending pulses to coid 
> returned by message_connect using MsgSendPulse.
> 
> Regards,
> Sesh