Mercurial > hg > nginx-quic
view src/os/unix/ngx_posix_config.h @ 4667:d05ab8793a69 stable-1.2
Merge of r4622, r4623: balancing changes.
*) Upstream: smooth weighted round-robin balancing.
For edge case weights like { 5, 1, 1 } we now produce { a, a, b, a, c, a, a }
sequence instead of { c, b, a, a, a, a, a } produced previously.
Algorithm is as follows: on each peer selection we increase current_weight
of each eligible peer by its weight, select peer with greatest current_weight
and reduce its current_weight by total number of weight points distributed
among peers.
In case of { 5, 1, 1 } weights this gives the following sequence of
current_weight's:
a b c
0 0 0 (initial state)
5 1 1 (a selected)
-2 1 1
3 2 2 (a selected)
-4 2 2
1 3 3 (b selected)
1 -4 3
6 -3 4 (a selected)
-1 -3 4
4 -2 5 (c selected)
4 -2 -2
9 -1 -1 (a selected)
2 -1 -1
7 0 0 (a selected)
0 0 0
To preserve weight reduction in case of failures the effective_weight
variable was introduced, which usually matches peer's weight, but is
reduced temporarily on peer failures.
This change also fixes loop with backup servers and proxy_next_upstream
http_404 (ticket #47), and skipping alive upstreams in some cases if there
are multiple dead ones (ticket #64).
*) Upstream: fixed ip_hash rebalancing with the "down" flag.
Due to weight being set to 0 for down peers, order of peers after sorting
wasn't the same as without the "down" flag (with down peers at the end),
resulting in client rebalancing for clients on other servers. The only
rebalancing which should happen after adding "down" to a server is one
for clients on the server.
The problem was introduced in r1377 (which fixed endless loop by setting
weight to 0 for down servers). The loop is no longer possible with new
smooth algorithm, so preserving original weight is safe.
| author | Maxim Dounin <mdounin@mdounin.ru> |
|---|---|
| date | Mon, 04 Jun 2012 11:21:58 +0000 |
| parents | b13419459a50 |
| children | 489839d07b38 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_POSIX_CONFIG_H_INCLUDED_ #define _NGX_POSIX_CONFIG_H_INCLUDED_ #if (NGX_HPUX) #define _XOPEN_SOURCE #define _XOPEN_SOURCE_EXTENDED 1 #endif #if (NGX_TRU64) #define _REENTRANT #endif #ifdef __CYGWIN__ #define timezonevar /* timezone is variable */ #define NGX_BROKEN_SCM_RIGHTS 1 #endif #include <sys/types.h> #include <sys/time.h> #if (NGX_HAVE_UNISTD_H) #include <unistd.h> #endif #if (NGX_HAVE_INTTYPES_H) #include <inttypes.h> #endif #include <stdarg.h> #include <stddef.h> /* offsetof() */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <signal.h> #include <pwd.h> #include <grp.h> #include <dirent.h> #include <glob.h> #include <time.h> #if (NGX_HAVE_SYS_PARAM_H) #include <sys/param.h> /* statfs() */ #endif #if (NGX_HAVE_SYS_MOUNT_H) #include <sys/mount.h> /* statfs() */ #endif #if (NGX_HAVE_SYS_STATVFS_H) #include <sys/statvfs.h> /* statvfs() */ #endif #if (NGX_HAVE_SYS_FILIO_H) #include <sys/filio.h> /* FIONBIO */ #endif #include <sys/ioctl.h> /* FIONBIO */ #include <sys/uio.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/wait.h> #include <sys/mman.h> #include <sys/resource.h> #include <sched.h> #include <sys/socket.h> #include <netinet/in.h> #include <netinet/tcp.h> /* TCP_NODELAY */ #include <arpa/inet.h> #include <netdb.h> #include <sys/un.h> #if (NGX_HAVE_LIMITS_H) #include <limits.h> /* IOV_MAX */ #endif #ifdef __CYGWIN__ #include <malloc.h> /* memalign() */ #endif #if (NGX_HAVE_CRYPT_H) #include <crypt.h> #endif #ifndef IOV_MAX #define IOV_MAX 16 #endif #include <ngx_auto_config.h> #if (NGX_HAVE_POSIX_SEM) #include <semaphore.h> #endif #if (NGX_HAVE_POLL) #include <poll.h> #endif #if (NGX_HAVE_KQUEUE) #include <sys/event.h> #endif #if (NGX_HAVE_DEVPOLL) #include <sys/ioctl.h> #include <sys/devpoll.h> #endif #if (NGX_HAVE_FILE_AIO) #include <aio.h> typedef struct aiocb ngx_aiocb_t; #endif #define NGX_LISTEN_BACKLOG 511 #define ngx_debug_init() #if (__FreeBSD__) && (__FreeBSD_version < 400017) #include <sys/param.h> /* ALIGN() */ /* * FreeBSD 3.x has no CMSG_SPACE() and CMSG_LEN() and has the broken CMSG_DATA() */ #undef CMSG_SPACE #define CMSG_SPACE(l) (ALIGN(sizeof(struct cmsghdr)) + ALIGN(l)) #undef CMSG_LEN #define CMSG_LEN(l) (ALIGN(sizeof(struct cmsghdr)) + (l)) #undef CMSG_DATA #define CMSG_DATA(cmsg) ((u_char *)(cmsg) + ALIGN(sizeof(struct cmsghdr))) #endif extern char **environ; #endif /* _NGX_POSIX_CONFIG_H_INCLUDED_ */