向子进程发送信号的问题

Question

I have a server that sets up a console handler with the SetConsoleCtrlHandler() function at startup and creates a number of child processes.
My goal is this:

• the server receives the CTRL+C signal

• the server generates the same signal to all active child processes of the same group

• the child processes manage the signal and correctly complete their execution

This is my code:

//handler for server.c
BOOL WINAPI CtrlHandler( DWORD fdwCtrlType ) 
{ 

    //CTRL_C_EVENT
    if(fdwCtrlType == CTRL_BREAK_EVENT)
    {
        newConf=1;
        return TRUE;
    }
    else if(fdwCtrlType == CTRL_C_EVENT)
    {
        //send CTRL+C to all process with the same groupId of calling process
        GenerateConsoleCtrlEvent(0,0);//
        return FALSE;     
    }
}

// server.c main
int main(int argc, char *argv[]) {
    ...
    ...
    if(!SetConsoleCtrlHandler(CtrlHandler, TRUE))
    {
        getLastError("SetConsoleCtrlHandler failed");//function written by me
        exit(EXIT_FAILURE);
    }
    ... 
    ...
    //This is how I create child processes (in a for loop)
    STARTUPINFO info;
    GetStartupInfo(&info);
    WSAPROTOCOL_INFO protInfo;
    PROCESS_INFORMATION processInfo;
    if(!CreateProcess("workerProcess.exe",command, NULL, NULL,0,CREATE_NEW_PROCESS_GROUP, NULL, NULL, &info, &processInfo))
    {
        fprintf(stderr, "could not create process.\n");
        return -1;
    }
    ...
    ...
}


//handler for child process(workerProcess.c)
BOOL WINAPI CtrlWorkerHandler( DWORD fdwCtrlType ) 
{ 

    //CTRL_C_EVENT
    if(fdwCtrlType == CTRL_C_EVENT)
    {
        printf("\nCLOSING WORKER\n");
        return FALSE;  
    }
    return TRUE; 
}

//workerProcess.c main
int main(int argc, char *argv[]) {
    ...
    ...
    if(!SetConsoleCtrlHandler(CtrlWorkerHandler, TRUE))
    {
        fprintf(stderr,"setConsoleCtrlHandler failed\n");
        exit(EXIT_FAILURE);
    }
    ...
    ...
}

The server correctly handles the CTRL + C signal, the GenerateConsoleCtrlEvent function does not fail so I assume it can send the signal to all processes that have the same groupid as the calling process, but unfortunately the workerProcess.exe process does not seem to handle the CTRL+C signal received from the parent process

Answer 1

Not sure and not able test right now, but I give it shot: by specifying CREATE_NEW_PROCESS_GROUP ( The new process is the root process of a new process group. ) for each worker process you basically create a new process group for each worker process.

Then, however, the call to GenerateConsoleCtrlEvent(0, 0) , where the second 0 says the signal is generated in all processes that share the console of the calling process. seems to be futile. All the worker processes are not even in the same process group as the calling process.

Probably, you should remove the CREATE_NEW_PROCESS_GROUP flag when creating the worker processes, or remember the lpProcessInformation.dwProcessId value for each worker process and invoke GenerateConsoleCtrlEvent for each.