system() function returns an error ECHILD on execution of a oracle client based program on RHEL-5

Issue

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Issue

• system() function returns an error ECHILD on execution of a oracle client based program on Red Hat Enterprise Linux 5
• The same program behaves correctly on Red Hat Enterprise Linux 4

Environment

• Red Hat Enterprise Linux 5
• Red Hat Enterprise Linux 4
• Oracle 11.2g database client

Resolution

• Add the clause "bequeath_detach=true" in sqlnet.ora
• Check with Oracle support for additional questions regarding this resolution

Root Cause

• The oracle client library 11.2g modifies the SIGCHLD handler and adds SA_NOCLDWAIT to the sa_flags for the signal. The effect of this is that any child process end thereafter does not result in a zombie process and any wait() or waitpid() call returns in an ECHILD.
• This behaviour new in oracle 11.2g and is not present in oracle 10.2g

Diagnostic Steps

The sample program below demonstrates the system() function behaviour in the presence of the SA_NOCLDWAIT flag:

#include <signal.h>
#include <stdio.h>

int main()
{
        struct sigaction dfl;
        sigset_t set;
        sigset_t oset;

        sigemptyset(&set);
        sigaddset(&set, SIGCHLD);

        dfl.sa_handler  = SIG_DFL;
        dfl.sa_flags    = SA_RESTART|SA_SIGINFO|SA_NOCLDWAIT;

        if (system("echo 1")<0)
                perror("system return1");

        sigprocmask(SIG_BLOCK, &set, NULL);
        sigaction(SIGCHLD, &dfl, NULL);
        sigprocmask(SIG_UNBLOCK, &set, NULL);

        if (system("echo 2") < 0)
                perror("system return2");
}