Thread getting reply blocked procnto!!!

I have a multithreaded application that uses sftp for file transfer

After running for some time i see one of the application thread is

331802 WLAN Processing REPLY 1

can anyone tell me why is this thread reply blocked on procnto, what can casue this?

Idenfied what causes the thread to get blocked on procnto…

This is the cause…
This thread lunches sftp session thru popen() command.
sftp launches ssh process and for some reason this is getting killed abruptly and becomes a zombie…

Now the focus is to identify the cause for the ssh process to get killed abruptly??

Does any had a similar experience??