HAProxy - Load balancer
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Willy Tarreau ca275d99ce BUG/MEDIUM: queue: make sure never to queue when there's no more served conns
Since commit 53f52e67a0 ("BUG/MEDIUM: queue: always dequeue the backend when
redistributing the last server"), we've got two reports again still showing
the theoretically impossible condition in pendconn_add(), including a single
threaded one.

Thanks to the traces, the issue could be tracked down to the redispatch part.
In fact, in non-determinist LB algorithms (RR, LC, FAS), we don't perform the
LB if there are pending connections in the backend, since it indicates that
previous attempts already failed, so we directly return SRV_STATUS_FULL. And
contrary to a previous belief, it is possible to meet this condition with
be->served==0 when redispatching (and likely with maxconn not greater than
the number of threads).

The problem is that in this case, the entry is queued and then the
pendconn_must_try_again() function checks if any connections are currently
being served to detect if we missed a race, and tries again, but that
situation is not caused by a concurrent thread and will never fix itself,
resulting in the loop.

All that part around pendconn_must_try_again() is still quite brittle, and
a safer approach would involve a sequence counter to detect new arrivals
and dequeues during the pendconn_add() call. But it's more sensitive work,
probably for a later fix.

This fix must be backported wherever the fix above was backported. Thanks
to Patrick Hemmer, as well as Damien Claisse and Basha Mougamadou from
Criteo for their help on tracking this one!
2024-10-16 18:08:39 +02:00
.github CI: QUIC Interop: use different artifact names for uploading logs 2024-08-26 11:19:41 +02:00
addons BUG/MEDIUM: promex: Wait to have the request before sending the response 2024-09-16 22:56:28 +02:00
admin CLEANUP: assorted typo fixes in the code and comments 2024-09-03 17:49:21 +02:00
dev DEV: flags/applet: decode appctx flags 2024-09-24 18:26:36 +02:00
doc DOC: design-thoughts: add diagrams illustrating an rx win groth 2024-10-12 16:38:36 +02:00
examples MEDIUM: protocol: add MPTCP per address support 2024-08-30 18:53:49 +02:00
include BUG/MEDIUM: server: server stuck in maintenance after FQDN change 2024-10-16 14:26:57 +02:00
reg-tests REGTESTS: fix a reload race in abns_socket.vtc 2024-10-14 19:15:21 +02:00
scripts SCRIPTS: create-release: no more need to skip architecture.txt 2024-07-10 15:38:45 +02:00
src BUG/MEDIUM: queue: make sure never to queue when there's no more served conns 2024-10-16 18:08:39 +02:00
tests MAJOR: import: update mt_list to support exponential back-off (try #2) 2024-07-09 16:46:38 +02:00
.cirrus.yml CI: cirrus-ci: bump FreeBSD image to 14-1 2024-10-14 14:28:26 +02:00
.gitattributes MINOR: Configure the cpp userdiff driver for *.[ch] in .gitattributes 2021-02-22 18:17:57 +01:00
.gitignore CONTRIB: Add vi file extensions to .gitignore 2023-06-02 18:14:34 +02:00
.mailmap DOC: update Tim's address in .mailmap 2021-09-16 09:14:14 +02:00
.travis.yml CI: travis-ci: temporarily disable arm64 builds 2021-08-07 07:28:15 +02:00
BRANCHES DOC: fix some spelling issues over multiple files 2021-01-08 14:53:47 +01:00
BSDmakefile BUILD: makefile: commit the tiny FreeBSD makefile stub 2023-05-24 17:17:36 +02:00
CHANGELOG [RELEASE] Released version 3.1-dev9 2024-10-03 17:47:33 +02:00
CONTRIBUTING CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
INSTALL DOC: install: don't reference removed CPU arg 2024-07-16 20:06:06 +02:00
LICENSE LICENSE: add licence exception for OpenSSL 2012-09-07 13:52:26 +02:00
MAINTAINERS MAJOR: spoe: Let the SPOE back into the game 2024-05-22 09:04:38 +02:00
Makefile REORG: buffers: move some of the heavy functions from buf.h to buf.c 2024-10-12 16:29:15 +02:00
README.md DOC: change the link to the FreeBSD CI in README.md 2024-06-03 15:21:29 +02:00
SUBVERS BUILD: use format tags in VERDATE and SUBVERS files 2013-12-10 11:22:49 +01:00
VERDATE [RELEASE] Released version 3.1-dev9 2024-10-03 17:47:33 +02:00
VERSION [RELEASE] Released version 3.1-dev9 2024-10-03 17:47:33 +02:00

HAProxy

alpine/musl AWS-LC openssl no-deprecated Illumos NetBSD FreeBSD VTest

HAProxy logo

HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.

Installation

The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.

Getting help

The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.

The issue tracker is only for bug reports or feature requests.

Documentation

The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.

Please refer to the following files depending on what you're looking for:

  • INSTALL for instructions on how to build and install HAProxy
  • BRANCHES to understand the project's life cycle and what version to use
  • LICENSE for the project's license
  • CONTRIBUTING for the process to follow to submit contributions

The more detailed documentation is located into the doc/ directory:

License

HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.