NGX_INVALID_PID   584 core/nginx.c           return NGX_INVALID_PID;
NGX_INVALID_PID   638 core/nginx.c           return NGX_INVALID_PID;
NGX_INVALID_PID   643 core/nginx.c       if (pid == NGX_INVALID_PID) {
NGX_INVALID_PID   106 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   119 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   132 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   140 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   148 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   155 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   163 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   171 os/unix/ngx_process.c             return NGX_INVALID_PID;
NGX_INVALID_PID   192 os/unix/ngx_process.c         return NGX_INVALID_PID;
NGX_INVALID_PID   620 os/unix/ngx_process_cycle.c                     == NGX_INVALID_PID)