Local fork of element-hq/synapse with carried patches. Upstream: https://github.com/element-hq/synapse
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Joerg Ziefle 3b6fe4570d Fix worker_lock busy loop in WaitingLock and WaitingMultiLock
`_get_next_retry_interval` was returning the OLD `_retry_interval`
value before doubling, instead of the new doubled value. Because
the returned value is what the lock-acquisition retry loop actually
sleeps on (via `timeout_deferred`), the actual sleep never grew
beyond its starting point of `0.1s`, producing a busy loop on the
very first iteration. The internal `_retry_interval` doubling
progressed normally, so the warning at >600s fired against an
exponentially-large value while the actual sleeps stayed tiny.

This is the cause of upstream issue #19588: under E2E one-time-key
upload contention (e.g., a misbehaving client repeatedly uploading
an OTK with a key id that already exists with a different value),
hundreds of waiters spin at ~0.1s polling intervals against the
lock store, pinning a single CPU at 100% and starving the HTTP
listener. Observed in production with v1.151.0 on a small server:
~1430 retry-loop occurrences in 10 minutes, ~70% CPU on synapse,
HTTP listener health checks timing out at 10s.

The fix is symmetric for both copies of the function (one in
`WaitingLock`, one in `WaitingMultiLock`): use `self._retry_interval`
consistently after doubling, both for the warning and for the
returned sleep duration. With this change the first sleep is
`max(5, 0.1*2) * jitter ≈ 5s`, growing 5 → 10 → 20 → 40 → 80 →
160 → 320 → 640 s, which is the intended exponential back-off.
2026-04-27 12:55:37 +00:00
.ci Hide successful, skipped Complement tests in the CI (#19590) 2026-03-23 15:16:23 +00:00
.github Bump dorny/paths-filter from 3.0.2 to 4.0.1 (#19625) 2026-03-31 10:20:36 +00:00
changelog.d 1.151.0 2026-04-07 14:15:50 +02:00
complement Allow Synapse to start up even when discovery fails for an OpenID Connect provider. (#19509) 2026-03-24 17:39:21 +00:00
contrib Remove the optional systemd-python dependency (#19491) 2026-03-09 15:11:04 +00:00
debian 1.151.0 2026-04-07 14:15:50 +02:00
demo Fix small comment typo in config output from the demo/start.sh script (#19538) 2026-03-30 11:14:25 -05:00
docker Allow Synapse to start up even when discovery fails for an OpenID Connect provider. (#19509) 2026-03-24 17:39:21 +00:00
docs Allow using HTTP/2 over plaintext when introspecting tokens with MAS (#19586) 2026-03-18 19:47:17 +01:00
rust Fix KNOWN_ROOM_VERSIONS.__contains__ raising TypeError for non-string keys (#19649) 2026-04-07 12:12:01 +00:00
schema 1.151.0rc1 2026-03-31 14:24:05 +02:00
scripts-dev complement.sh: ensure old complement checkout files are deleted; remove -N wget flag (#19592) 2026-03-20 16:30:03 +00:00
stubs Write union types as X | Y where possible (#19111) 2025-11-06 14:02:33 -06:00
synapse Fix worker_lock busy loop in WaitingLock and WaitingMultiLock 2026-04-27 12:55:37 +00:00
synmark Port Clock functions to use Duration class (#19229) 2025-12-01 13:55:06 +00:00
tests Fix KNOWN_ROOM_VERSIONS.__contains__ raising TypeError for non-string keys (#19649) 2026-04-07 12:12:01 +00:00
.codecov.yml Disable codecov reports to GH comments. 2019-07-31 10:56:02 +01:00
.coveragerc Fix coverage in sytest and use plugins for buildkite (#5922) 2019-08-29 22:19:57 +10:00
.dockerignore Fix pinning Rust deps in docker images (#14129) 2022-10-11 10:53:34 +00:00
.editorconfig Apply correct editorconfig to .pyi files (#14526) 2022-11-22 18:33:28 +00:00
.git-blame-ignore-revs Ignore Python language refactors (.git-blame-ignore-revs) (#19150) 2025-11-10 22:34:30 +00:00
.gitignore Add .zed/ to .gitignore (#18623) 2025-07-08 11:57:23 +01:00
.rustfmt.toml Prevent dirty Cargo.lock changes from install (#18693) 2025-07-18 10:28:10 -05:00
AUTHORS.rst Automatically delete empty groups/communities (#6453) 2019-12-16 12:12:40 +00:00
book.toml Bump mdbook from 0.4.17 -> 0.5.2 and remove custom table-of-contents plugin (#19356) 2026-01-07 18:46:03 +00:00
build_rust.py Drop Python 3.9, bump tests/builds to Python 3.10 (#19099) 2025-10-29 12:15:00 -05:00
Cargo.lock Bump once_cell from 1.21.3 to 1.21.4 in the patches group (#19623) 2026-03-31 11:45:52 +00:00
Cargo.toml Fix building rust with nightly (#15906) 2023-07-10 16:24:04 +01:00
CHANGES.md Fix the changelog 2026-04-07 14:30:11 +02:00
CONTRIBUTING.md Update the contributing guide after reliecensing (#16772) 2024-01-03 11:31:03 +00:00
flake.lock Fix nix flake 2024-11-20 15:01:56 +00:00
flake.nix Replace PyICU with Rust icu_segmenter crate (#18553) 2025-07-03 11:12:12 +01:00
INSTALL.md Update book location 2023-12-13 16:15:22 +00:00
LICENSE-AGPL-3.0 make dual licensing explicit (#18134) 2025-02-05 13:40:10 +00:00
LICENSE-COMMERCIAL make dual licensing explicit (#18134) 2025-02-05 13:40:10 +00:00
mypy.ini Migrate dev dependencies to PEP 735 dependency groups (#19490) 2026-03-17 14:45:28 +00:00
poetry.lock Bump phonenumbers from 9.0.25 to 9.0.26 in the minor-and-patches group (#19627) 2026-03-31 11:33:34 +00:00
pyproject.toml 1.151.0 2026-04-07 14:15:50 +02:00
README.rst Update Element logo to be an absolute URL, so it will render on PyPI (#19368) 2026-01-13 12:03:34 +00:00
sytest-blacklist Use full GitHub links instead of bare issue numbers. (#16637) 2023-11-15 08:02:11 -05:00
tox.ini Drop Python 3.9, bump tests/builds to Python 3.10 (#19099) 2025-10-29 12:15:00 -05:00
UPGRADE.rst Update book location 2023-12-13 16:15:22 +00:00

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.. image:: https://github.com/element-hq/synapse/raw/develop/docs/element_logo_white_bg.svg
   :height: 60px

**Element Synapse - Matrix homeserver implementation**

|support| |development| |documentation| |license| |pypi| |python|

Synapse is an open source `Matrix <https://matrix.org>`__ homeserver
implementation, written and maintained by `Element <https://element.io>`_.
`Matrix <https://github.com/matrix-org>`__ is the open standard for secure and
interoperable real-time communications. You can directly run and manage the
source code in this repository, available under an AGPL license (or
alternatively under a commercial license from Element).

There is no support provided by Element unless you have a subscription from
Element.

🚀 Getting started
==================

This component is developed and maintained by `Element <https://element.io>`_.
It gets shipped as part of the **Element Server Suite (ESS)** which provides the
official means of deployment.

ESS is a Matrix distribution from Element with focus on quality and ease of use.
It ships a full Matrix stack tailored to the respective use case.

There are three editions of ESS:

- `ESS Community <https://github.com/element-hq/ess-helm>`_ - the free Matrix
  distribution from Element tailored to small-/mid-scale, non-commercial
  community use cases
- `ESS Pro <https://element.io/server-suite>`_ - the commercial Matrix
  distribution from Element for professional use
- `ESS TI-M <https://element.io/server-suite/ti-messenger>`_ - a special version
  of ESS Pro focused on the requirements of TI-Messenger Pro and ePA as
  specified by the German National Digital Health Agency Gematik


🛠️ Standalone installation and configuration
============================================

The Synapse documentation describes `options for installing Synapse standalone
<https://element-hq.github.io/synapse/latest/setup/installation.html>`_. See
below for more useful documentation links.

- `Synapse configuration options <https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html>`_
- `Synapse configuration for federation <https://element-hq.github.io/synapse/latest/federate.html>`_
- `Using a reverse proxy with Synapse <https://element-hq.github.io/synapse/latest/reverse_proxy.html>`_
- `Upgrading Synapse <https://element-hq.github.io/synapse/develop/upgrade.html>`_


🎯 Troubleshooting and support
==============================

🚀 Professional support
-----------------------

Enterprise quality support for Synapse including SLAs is available as part of an
`Element Server Suite (ESS) <https://element.io/pricing>`_ subscription.

If you are an existing ESS subscriber then you can raise a `support request <https://ems.element.io/support>`_
and access the `Element product documentation <https://docs.element.io>`_.

🤝 Community support
--------------------

The `Admin FAQ <https://element-hq.github.io/synapse/latest/usage/administration/admin_faq.html>`_
includes tips on dealing with some common problems. For more details, see
`Synapse's wider documentation <https://element-hq.github.io/synapse/latest/>`_.

For additional support installing or managing Synapse, please ask in the community
support room |room|_ (from a matrix.org account if necessary). We do not use GitHub
issues for support requests, only for bug reports and feature requests.

.. |room| replace:: ``#synapse:matrix.org``
.. _room: https://matrix.to/#/#synapse:matrix.org

.. |docs| replace:: ``docs``
.. _docs: docs


🛠️ Development
==============

We welcome contributions to Synapse from the community!
The best place to get started is our
`guide for contributors <https://element-hq.github.io/synapse/latest/development/contributing_guide.html>`_.
This is part of our broader `documentation <https://element-hq.github.io/synapse/latest>`_, which includes
information for Synapse developers as well as Synapse administrators.

Developers might be particularly interested in:

* `Synapse's database schema <https://element-hq.github.io/synapse/latest/development/database_schema.html>`_,
* `notes on Synapse's implementation details <https://element-hq.github.io/synapse/latest/development/internal_documentation/index.html>`_, and
* `how we use git <https://element-hq.github.io/synapse/latest/development/git.html>`_.

Alongside all that, join our developer community on Matrix:
`#synapse-dev:matrix.org <https://matrix.to/#/#synapse-dev:matrix.org>`_, featuring real humans!

Copyright and Licensing
=======================

  | Copyright 20142017 OpenMarket Ltd
  | Copyright 2017 Vector Creations Ltd
  | Copyright 20172025 New Vector Ltd
  | Copyright 2025 Element Creations Ltd

This software is dual-licensed by Element Creations Ltd (Element). It can be
used either:

(1) for free under the terms of the GNU Affero General Public License (as
    published by the Free Software Foundation, either version 3 of the License,
    or (at your option) any later version); OR

(2) under the terms of a paid-for Element Commercial License agreement between
    you and Element (the terms of which may vary depending on what you and
    Element have agreed to).

Unless required by applicable law or agreed to in writing, software distributed
under the Licenses is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied. See the Licenses for the
specific language governing permissions and limitations under the Licenses.

Please contact `licensing@element.io <mailto:licensing@element.io>`_ to purchase
an Element commercial license for this software.


.. |support| image:: https://img.shields.io/badge/matrix-community%20support-success
  :alt: (get community support in #synapse:matrix.org)
  :target: https://matrix.to/#/#synapse:matrix.org

.. |development| image:: https://img.shields.io/matrix/synapse-dev:matrix.org?label=development&logo=matrix
  :alt: (discuss development on #synapse-dev:matrix.org)
  :target: https://matrix.to/#/#synapse-dev:matrix.org

.. |documentation| image:: https://img.shields.io/badge/documentation-%E2%9C%93-success
  :alt: (Rendered documentation on GitHub Pages)
  :target: https://element-hq.github.io/synapse/latest/

.. |license| image:: https://img.shields.io/github/license/element-hq/synapse
  :alt: (check license in LICENSE file)
  :target: LICENSE

.. |pypi| image:: https://img.shields.io/pypi/v/matrix-synapse
  :alt: (latest version released on PyPi)
  :target: https://pypi.org/project/matrix-synapse

.. |python| image:: https://img.shields.io/pypi/pyversions/matrix-synapse
  :alt: (supported python versions)
  :target: https://pypi.org/project/matrix-synapse