FCGX_Accept_r fails with -88 return code

I am writing a fastcgi app in c++ and am struggling with FCGX_Accept_r() exiting without blocking with return value of "-88". After doing lots of googling I found out that you have to properly init FCGX structs, correct umask on the uds socket, don't forget to FCGX_Init() and check return code of FCGX_Init() and FCGX_InitRequest().

I've done all above for my program and still result is the same.

So i have tried to build the example C app from fcgi site here: http://www.fastcgi.com/devkit/examples/threaded.c and it exited immediately.

The strange thing is that they don't have any sockets open there. So i have added a couple of lines - print out FCGX_Accept_() return value and open a uds socket.

Here is the resulting code:

/*
 * threaded.c -- A simple multi-threaded FastCGI application.
 */

#ifndef lint
static const char rcsid[] = "$Id: threaded.c,v 1.9 2001/11/20 03:23:21 robs Exp $";
#endif /* not lint */

#include "fcgi_config.h"

#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <stdio.h>
#include "fcgiapp.h"


#define THREAD_COUNT 20

static int counts[THREAD_COUNT];

static void *doit(void *a)
{
    int rc, i, thread_id = (int)a;
    pid_t pid = getpid();
    FCGX_Request request;
    char *server_name;

    FCGX_InitRequest(&request, 0, 0);

    for (;;)
    {
        static pthread_mutex_t accept_mutex = PTHREAD_MUTEX_INITIALIZER;
        static pthread_mutex_t counts_mutex = PTHREAD_MUTEX_INITIALIZER;

        /* Some platforms require accept() serialization, some don't.. */
        pthread_mutex_lock(&accept_mutex);
        rc = FCGX_Accept_r(&request);
        pthread_mutex_unlock(&accept_mutex);

        if (rc < 0) {
        printf("failed accept: %d\n", rc);
            break;
    }

        server_name = FCGX_GetParam("SERVER_NAME", request.envp);

        FCGX_FPrintF(request.out,
            "Content-type: text/html\r\n"
            "\r\n"
            "<title>FastCGI Hello! (multi-threaded C, fcgiapp library)</title>"
            "<h1>FastCGI Hello! (multi-threaded C, fcgiapp library)</h1>"
            "Thread %d, Process %ld<p>"
            "Request counts for %d threads running on host <i>%s</i><p><code>",
            thread_id, pid, THREAD_COUNT, server_name ? server_name : "?");

        sleep(2);

        pthread_mutex_lock(&counts_mutex);
        ++counts[thread_id];
        for (i = 0; i < THREAD_COUNT; i++)
            FCGX_FPrintF(request.out, "%5d " , counts[i]);
        pthread_mutex_unlock(&counts_mutex);

        FCGX_Finish_r(&request);
    }

    return NULL;
}

int main(void)
{
    int i;
    pthread_t id[THREAD_COUNT];

    FCGX_Init();

    umask(0);
    FCGX_OpenSocket("/tmp/fcgi.sock", 10);

    for (i = 1; i < THREAD_COUNT; i++)
        pthread_create(&id[i], NULL, doit, (void*)i);

    doit(0);

    return 0;
}

And guess what:

# gcc fcgi.c -lpthread -lfcgi         
# ./a.out
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -88
failed accept: -failed accept: -88

Could anyone please point out what am I doint wrong? Thank you!

Update:

Interesting thing is that example from here https://habrahabr.ru/post/154187/ works. And I don't see much difference.

The problem was that in the example they use

FCGX_InitRequest(&request, 0, 0);

while the second argument must be socket id. Nice examples, guys.