Fixing cpu hog with all upstream servers marked "down". The following configuration causes nginx to hog cpu due to infinite loop in ngx_http_upstream_get_peer(): upstream backend { server 127.0.0.1:8080 down; server 127.0.0.1:8080 down; } server { ... location / { proxy_pass http://backend; } } Make sure we don't loop infinitely in ngx_http_upstream_get_peer() but stop after resetting peer weights once. Return 0 if we are stuck. This is guaranteed to work as peer 0 always exists, and eventually ngx_http_upstream_get_round_robin_peer() will do the right thing falling back to backup servers or returning NGX_BUSY.

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>


#if (NGX_CRYPT)

ngx_int_t
ngx_libc_crypt(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted)
{
    /* STUB: a plain text password */

    *encrypted = key;

    return NGX_OK;
}

#endif /* NGX_CRYPT */