Valgrind with signal handling - c++

Question

In this code, I am trying to ipc with signals. Parent process will send SIGUSR1 signal to his children and waits for a SIGUSR1 signal for conformation of the signal arrive at the child end.
So I have;
Parent --> SIGUSR1 --> CHILD[i]
Parent <--- SIGUSR1 <--- CHILD[i]
this kind of communication between parent child processes. In normal executing, I have never face with a deadlock scenario. But when I run with valgrind, sometimes child process canot receive SIGUSR1 signal from parent process, which is start signal for communication.
Is the valgrind uses some mechanisms to avoid signal communication between processes ?
Parent process :
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <errno.h>
#define CHILD_SIZE 80
sigset_t sigusr_mask;
pid_t children[CHILD_SIZE];
void SIGUSR1_handler(int sig)
{
write(1,"test.\n",6);
}
void init_signal()
{
sigset_t blck_msk;
sigemptyset(&blck_msk);
sigaddset(&blck_msk, SIGUSR1);
sigfillset(&sigusr_mask);
sigdelset(&sigusr_mask, SIGUSR1);
struct sigaction usr1_act;
memset(&usr1_act, 0, sizeof(usr1_act));
usr1_act.sa_handler = &SIGUSR1_handler;
sigaction(SIGUSR1, &usr1_act, NULL);
if(-1== sigprocmask(SIG_BLOCK, &blck_msk,NULL))
exit(-1);
}
void create_children(const char* processPath, int round_)
{
for(int i = 0; i < CHILD_SIZE; ++i)
{
pid_t pid_c = fork();
if(pid_c > 0) {
children[i] = pid_c;
}
else if(pid_c == 0)
{
char* arg[1024] = {"childProcess", (char*)0};
execve(processPath, arg, NULL);
}
}
}
// for the synchronization
void wait_childs()
{
for (int i = 0; i < CHILD_SIZE; ++i)
{
// send SIGUSR1 to the children.
kill(children[i], SIGUSR1);
printf("%d : %s\n", children[i],strerror(errno));
// wait until children reply by SIGUSR1
sigsuspend(&sigusr_mask);
}
}
int main(int argc, char const *argv[])
{
init_signal();
create_children("childProcess", 1);
wait_childs();
return (0);
}
Child process :
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include "utils.h"
sigset_t sigusr_mask;
void SIGUSR1_handler(int sig) {
write(1,"usr1\n",4);
}
void init_signal()
{
sigfillset(&sigusr_mask);
sigdelset(&sigusr_mask, SIGUSR1);
struct sigaction usr1_act;
memset(&usr1_act, 0, sizeof(usr1_act));
usr1_act.sa_handler = &SIGUSR1_handler;
sigaction(SIGUSR1, &usr1_act, NULL);
}
int main(int argc, char const *argv[])
{
init_signal();
printf("child %d waiting \n",getpid());
// wait until parent starts the communication.
sigsuspend(&sigusr_mask);
// after parent sends SIGUSR1, send reply.
kill(getppid(), SIGUSR1);
return 0;
}