gdb hangs when it calls tcsetpgrp.

Christopher Faylor
Thu Jun 27 17:52:00 GMT 2013

On Fri, Jun 28, 2013 at 02:30:42AM +0900, jojelino wrote:
>I was using gdb for debugging ffmpeg raising SIGFPE. but gdb hangs after 
>entering command among of s,n,si,ni.
>gdb has same pgrp over pgrp of debuggee. when tcsetpgrp is called in 
>gdb, you already know it sends __SIGSETPGRP signal to suspended 
>debuggee. but the debugger already suspended all thread of debuggee 
>without distinguishing whether the victim thread is wait_sig or not. so 
>the suspend process doesn't wake up until debugger handles debug event. 
>which is the cause of hang.
>Although it seems that cygwin developers have already aware of sort of 
>this issue according to, so, it would be good if 
>cygwin can defer sending signal that would block for sure.

Yep.  I've mentioned this issue here several times.  You should use
mintty for debugging.  It does not have this problem.


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