[3.5.3] Application gets into WAIT MODE with error from sig_send signaling error from cygwin1.dll

[Abinash Mohanty (amohanty)]

Hi,

Problem Statement
Our application is getting into wait mode after running for some time and Cygwin continues to throw the below  Exception Error:
1599350352 [sig] my_app 741 sig_send: error sending signal 11, pid 741, pipe handle 0x130, nb 0, packsize 176, Win32 error 0

Problem Description
We have initialized and used SIGUSR1, SIGALARAM and SIGPIPE signals in our code. We are using below Cygwin APIs for initializing or adding the signals
     sigset_t signal_set;

     sigemptyset(&signal_set);
     sigaddset(&signal_set, SIGUSR1);
     sigaddset(&signal_set, SIGALRM);
     sigaddset(&signal_set, SIGPIPE);


Masking the signals using  pthread_sigmask()

Catch the signals and process them
void HandleSignals()
{
    int sig_number;

    for(;;) {

        sig_wait(signal_set,sig_number);

        switch(sig_number) {
        case SIGUSR1:
            {
            pthread_mutex_lock(&m_mutex);

            //Handing the SIGUSR1 signals
            pthread_mutex_unlock(&m_mutex);
            }
            break;
        case SIGALRM:
            //Handing the SIGALRM signals
            break;
        default:
            break;
        } /* end switch */

    }
}

However after running my application multiple times which makes use of Cygwin Signaling our application goes into WAIT MODE(probably waiting for signals) and we get the  below error message continuously in our console.
1599350352 [sig] my_app 741 sig_send: error sending signal 11, pid 741, pipe handle 0x130, nb 0, packsize 176, Win32 error 0

Our application is blocked due to this error and we are unable to proceed further.
Attaching strace logs and adding few error log here as well:-

  165 46400560 [main] my_app 6964 select_stuff::wait: m 4, us 100000, wmfo_timeout -1
   81 46400641 [socksel] my_app 6964 SetThreadName: SetThreadDescription() failed. 00000000 10000000
  100 46400741 [socksel] my_app 6964 thread_socket: stuff_start 0x7FFFFB198, timeout 4294967295
   58 46400799 [socksel] my_app 6964 peek_socket: read_ready: 0, write_ready: 0, except_ready: 0
76569 46477368 [sig] my_app 6964 sigpacket::process: signal 30 processing
   86 46477454 [sig] my_app 6964 init_cygheap::find_tls: sig 30
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
  162 46477616 [sig] my_app 6964 exception::handle: In cygwin_except_handler exception 0xC0000005 at 0x7FFB486AAFFA sp 0x289C990
   36 46477652 [sig] my_app 6964 exception::handle: In cygwin_except_handler signal 11 at 0x7FFB486AAFFA
   53 46477705 [sig] my_app 6964 break_here: break here
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa
--- Process 5016 (pid: 6964), exception c0000005 at 00007ffb486aaffa

Also attaching the output of cygcheck -s -v -r > cygcheck.out

As this is a blocker issue for our application , quick resolution would really help to proceed further.
Please let us know if you need more information.

Thanks and Regards,
Abinash Mohanty




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