1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>Understanding Synapse Through Grafana Graphs - Synapse</title>
<!-- Custom HTML head -->
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#ffffff" />
<link rel="icon" href="../../favicon.svg">
<link rel="shortcut icon" href="../../favicon.png">
<link rel="stylesheet" href="../../css/variables.css">
<link rel="stylesheet" href="../../css/general.css">
<link rel="stylesheet" href="../../css/chrome.css">
<link rel="stylesheet" href="../../css/print.css" media="print">
<!-- Fonts -->
<link rel="stylesheet" href="../../FontAwesome/css/font-awesome.css">
<link rel="stylesheet" href="../../fonts/fonts.css">
<!-- Highlight.js Stylesheets -->
<link rel="stylesheet" href="../../highlight.css">
<link rel="stylesheet" href="../../tomorrow-night.css">
<link rel="stylesheet" href="../../ayu-highlight.css">
<!-- Custom theme stylesheets -->
<link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
<link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
<link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
</head>
<body>
<!-- Provide site root to javascript -->
<script type="text/javascript">
var path_to_root = "../../";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script type="text/javascript">
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') && theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
</script>
<!-- Set the theme before any content is loaded, prevents flash -->
<script type="text/javascript">
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('light')
html.classList.add(theme);
html.classList.add('js');
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script type="text/javascript">
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div class="sidebar-scrollbox">
<ol class="chapter"><li class="chapter-item expanded affix "><li class="part-title">Introduction</li><li class="chapter-item expanded "><a href="../../welcome_and_overview.html">Welcome and Overview</a></li><li class="chapter-item expanded affix "><li class="part-title">Setup</li><li class="chapter-item expanded "><a href="../../setup/installation.html">Installation</a></li><li class="chapter-item expanded "><a href="../../postgres.html">Using Postgres</a></li><li class="chapter-item expanded "><a href="../../reverse_proxy.html">Configuring a Reverse Proxy</a></li><li class="chapter-item expanded "><a href="../../setup/forward_proxy.html">Configuring a Forward/Outbound Proxy</a></li><li class="chapter-item expanded "><a href="../../turn-howto.html">Configuring a Turn Server</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../setup/turn/coturn.html">coturn TURN server</a></li><li class="chapter-item expanded "><a href="../../setup/turn/eturnal.html">eturnal TURN server</a></li></ol></li><li class="chapter-item expanded "><a href="../../delegate.html">Delegation</a></li><li class="chapter-item expanded affix "><li class="part-title">Upgrading</li><li class="chapter-item expanded "><a href="../../upgrade.html">Upgrading between Synapse Versions</a></li><li class="chapter-item expanded affix "><li class="part-title">Usage</li><li class="chapter-item expanded "><a href="../../federate.html">Federation</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/index.html">Configuration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../usage/configuration/config_documentation.html">Configuration Manual</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/homeserver_sample_config.html">Homeserver Sample Config File</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/logging_sample_config.html">Logging Sample Config File</a></li><li class="chapter-item expanded "><a href="../../structured_logging.html">Structured Logging</a></li><li class="chapter-item expanded "><a href="../../templates.html">Templates</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/user_authentication/index.html">User Authentication</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../usage/configuration/user_authentication/single_sign_on/index.html">Single-Sign On</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../openid.html">OpenID Connect</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/user_authentication/single_sign_on/saml.html">SAML</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/user_authentication/single_sign_on/cas.html">CAS</a></li><li class="chapter-item expanded "><a href="../../sso_mapping_providers.html">SSO Mapping Providers</a></li></ol></li><li class="chapter-item expanded "><a href="../../password_auth_providers.html">Password Auth Providers</a></li><li class="chapter-item expanded "><a href="../../jwt.html">JSON Web Tokens</a></li><li class="chapter-item expanded "><a href="../../usage/configuration/user_authentication/refresh_tokens.html">Refresh Tokens</a></li></ol></li><li class="chapter-item expanded "><a href="../../CAPTCHA_SETUP.html">Registration Captcha</a></li><li class="chapter-item expanded "><a href="../../application_services.html">Application Services</a></li><li class="chapter-item expanded "><a href="../../server_notices.html">Server Notices</a></li><li class="chapter-item expanded "><a href="../../consent_tracking.html">Consent Tracking</a></li><li class="chapter-item expanded "><a href="../../user_directory.html">User Directory</a></li><li class="chapter-item expanded "><a href="../../message_retention_policies.html">Message Retention Policies</a></li><li class="chapter-item expanded "><a href="../../modules/index.html">Pluggable Modules</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../modules/writing_a_module.html">Writing a module</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../modules/spam_checker_callbacks.html">Spam checker callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/third_party_rules_callbacks.html">Third-party rules callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/presence_router_callbacks.html">Presence router callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/account_validity_callbacks.html">Account validity callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/password_auth_provider_callbacks.html">Password auth provider callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/background_update_controller_callbacks.html">Background update controller callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/account_data_callbacks.html">Account data callbacks</a></li><li class="chapter-item expanded "><a href="../../modules/porting_legacy_module.html">Porting a legacy module to the new interface</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../../workers.html">Workers</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../synctl_workers.html">Using synctl with Workers</a></li><li class="chapter-item expanded "><a href="../../systemd-with-workers/index.html">Systemd</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../../usage/administration/index.html">Administration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../usage/administration/admin_api/index.html">Admin API</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../admin_api/account_validity.html">Account Validity</a></li><li class="chapter-item expanded "><a href="../../usage/administration/admin_api/background_updates.html">Background Updates</a></li><li class="chapter-item expanded "><a href="../../admin_api/event_reports.html">Event Reports</a></li><li class="chapter-item expanded "><a href="../../admin_api/experimental_features.html">Experimental Features</a></li><li class="chapter-item expanded "><a href="../../admin_api/media_admin_api.html">Media</a></li><li class="chapter-item expanded "><a href="../../admin_api/purge_history_api.html">Purge History</a></li><li class="chapter-item expanded "><a href="../../admin_api/register_api.html">Register Users</a></li><li class="chapter-item expanded "><a href="../../usage/administration/admin_api/registration_tokens.html">Registration Tokens</a></li><li class="chapter-item expanded "><a href="../../admin_api/room_membership.html">Manipulate Room Membership</a></li><li class="chapter-item expanded "><a href="../../admin_api/rooms.html">Rooms</a></li><li class="chapter-item expanded "><a href="../../admin_api/server_notices.html">Server Notices</a></li><li class="chapter-item expanded "><a href="../../admin_api/statistics.html">Statistics</a></li><li class="chapter-item expanded "><a href="../../admin_api/user_admin_api.html">Users</a></li><li class="chapter-item expanded "><a href="../../admin_api/version_api.html">Server Version</a></li><li class="chapter-item expanded "><a href="../../usage/administration/admin_api/federation.html">Federation</a></li></ol></li><li class="chapter-item expanded "><a href="../../manhole.html">Manhole</a></li><li class="chapter-item expanded "><a href="../../metrics-howto.html">Monitoring</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../usage/administration/monitoring/reporting_homeserver_usage_statistics.html">Reporting Homeserver Usage Statistics</a></li></ol></li><li class="chapter-item expanded "><a href="../../usage/administration/monthly_active_users.html">Monthly Active Users</a></li><li class="chapter-item expanded "><a href="../../usage/administration/understanding_synapse_through_grafana_graphs.html" class="active">Understanding Synapse Through Grafana Graphs</a></li><li class="chapter-item expanded "><a href="../../usage/administration/useful_sql_for_admins.html">Useful SQL for Admins</a></li><li class="chapter-item expanded "><a href="../../usage/administration/database_maintenance_tools.html">Database Maintenance Tools</a></li><li class="chapter-item expanded "><a href="../../usage/administration/state_groups.html">State Groups</a></li><li class="chapter-item expanded "><a href="../../usage/administration/request_log.html">Request log format</a></li><li class="chapter-item expanded "><a href="../../usage/administration/admin_faq.html">Admin FAQ</a></li><li class="chapter-item expanded "><div>Scripts</div></li></ol></li><li class="chapter-item expanded "><li class="part-title">Development</li><li class="chapter-item expanded "><a href="../../development/contributing_guide.html">Contributing Guide</a></li><li class="chapter-item expanded "><a href="../../code_style.html">Code Style</a></li><li class="chapter-item expanded "><a href="../../development/reviews.html">Reviewing Code</a></li><li class="chapter-item expanded "><a href="../../development/releases.html">Release Cycle</a></li><li class="chapter-item expanded "><a href="../../development/git.html">Git Usage</a></li><li class="chapter-item expanded "><div>Testing</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../development/demo.html">Demo scripts</a></li></ol></li><li class="chapter-item expanded "><a href="../../opentracing.html">OpenTracing</a></li><li class="chapter-item expanded "><a href="../../development/database_schema.html">Database Schemas</a></li><li class="chapter-item expanded "><a href="../../development/experimental_features.html">Experimental features</a></li><li class="chapter-item expanded "><a href="../../development/dependencies.html">Dependency management</a></li><li class="chapter-item expanded "><div>Synapse Architecture</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../development/synapse_architecture/cancellation.html">Cancellation</a></li><li class="chapter-item expanded "><a href="../../log_contexts.html">Log Contexts</a></li><li class="chapter-item expanded "><a href="../../replication.html">Replication</a></li><li class="chapter-item expanded "><a href="../../development/synapse_architecture/streams.html">Streams</a></li><li class="chapter-item expanded "><a href="../../tcp_replication.html">TCP Replication</a></li><li class="chapter-item expanded "><a href="../../development/synapse_architecture/faster_joins.html">Faster remote joins</a></li></ol></li><li class="chapter-item expanded "><a href="../../development/internal_documentation/index.html">Internal Documentation</a></li><li><ol class="section"><li class="chapter-item expanded "><div>Single Sign-On</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../development/saml.html">SAML</a></li><li class="chapter-item expanded "><a href="../../development/cas.html">CAS</a></li></ol></li><li class="chapter-item expanded "><a href="../../development/room-dag-concepts.html">Room DAG concepts</a></li><li class="chapter-item expanded "><div>State Resolution</div></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../auth_chain_difference_algorithm.html">The Auth Chain Difference Algorithm</a></li></ol></li><li class="chapter-item expanded "><a href="../../media_repository.html">Media Repository</a></li><li class="chapter-item expanded "><a href="../../room_and_user_statistics.html">Room and User Statistics</a></li></ol></li><li class="chapter-item expanded "><div>Scripts</div></li><li class="chapter-item expanded affix "><li class="part-title">Other</li><li class="chapter-item expanded "><a href="../../deprecation_policy.html">Dependency Deprecation Policy</a></li><li class="chapter-item expanded "><a href="../../other/running_synapse_on_single_board_computers.html">Running Synapse on a Single-Board Computer</a></li></ol>
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
</nav>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar-hover-placeholder"></div>
<div id="menu-bar" class="menu-bar sticky bordered">
<div class="left-buttons">
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</button>
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
<i class="fa fa-paint-brush"></i>
</button>
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
</ul>
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
<i class="fa fa-search"></i>
</button>
</div>
<h1 class="menu-title">Synapse</h1>
<div class="right-buttons">
<a href="../../print.html" title="Print this book" aria-label="Print this book">
<i id="print-button" class="fa fa-print"></i>
</a>
<a href="https://github.com/matrix-org/synapse" title="Git repository" aria-label="Git repository">
<i id="git-repository-button" class="fa fa-github"></i>
</a>
<a href="https://github.com/matrix-org/synapse/edit/develop/docs/usage/administration/understanding_synapse_through_grafana_graphs.md" title="Suggest an edit" aria-label="Suggest an edit">
<i id="git-edit-button" class="fa fa-edit"></i>
</a>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
</form>
<div id="searchresults-outer" class="searchresults-outer hidden">
<div id="searchresults-header" class="searchresults-header"></div>
<ul id="searchresults">
</ul>
</div>
</div>
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
<script type="text/javascript">
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
</script>
<div id="content" class="content">
<main>
<!-- Page table of contents -->
<div class="sidetoc">
<nav class="pagetoc"></nav>
</div>
<h2 id="understanding-synapse-through-grafana-graphs"><a class="header" href="#understanding-synapse-through-grafana-graphs">Understanding Synapse through Grafana graphs</a></h2>
<p>It is possible to monitor much of the internal state of Synapse using <a href="https://prometheus.io">Prometheus</a>
metrics and <a href="https://grafana.com/">Grafana</a>.
A guide for configuring Synapse to provide metrics is available <a href="../../metrics-howto.html">here</a>
and information on setting up Grafana is <a href="https://github.com/matrix-org/synapse/tree/master/contrib/grafana">here</a>.
In this setup, Prometheus will periodically scrape the information Synapse provides and
store a record of it over time. Grafana is then used as an interface to query and
present this information through a series of pretty graphs.</p>
<p>Once you have grafana set up, and assuming you're using <a href="https://github.com/matrix-org/synapse/blob/master/contrib/grafana/synapse.json">our grafana dashboard template</a>, look for the following graphs when debugging a slow/overloaded Synapse:</p>
<h2 id="message-event-send-time"><a class="header" href="#message-event-send-time">Message Event Send Time</a></h2>
<p><img src="https://user-images.githubusercontent.com/1342360/82239409-a1c8e900-9930-11ea-8081-e4614e0c63f4.png" alt="image" /></p>
<p>This, along with the CPU and Memory graphs, is a good way to check the general health of your Synapse instance. It represents how long it takes for a user on your homeserver to send a message.</p>
<h2 id="transaction-count-and-transaction-duration"><a class="header" href="#transaction-count-and-transaction-duration">Transaction Count and Transaction Duration</a></h2>
<p><img src="https://user-images.githubusercontent.com/1342360/82239985-8d392080-9931-11ea-80d0-843ab2f22e1e.png" alt="image" /></p>
<p><img src="https://user-images.githubusercontent.com/1342360/82240050-ab068580-9931-11ea-98f1-f94671cbac9a.png" alt="image" /></p>
<p>These graphs show the database transactions that are occurring the most frequently, as well as those are that are taking the most amount of time to execute.</p>
<p><img src="https://user-images.githubusercontent.com/1342360/82240192-e86b1300-9931-11ea-9aac-3e2c9bfa6fdc.png" alt="image" /></p>
<p>In the first graph, we can see obvious spikes corresponding to lots of <code>get_user_by_id</code> transactions. This would be useful information to figure out which part of the Synapse codebase is potentially creating a heavy load on the system. However, be sure to cross-reference this with Transaction Duration, which states that <code>get_users_by_id</code> is actually a very quick database transaction and isn't causing as much load as others, like <code>persist_events</code>:</p>
<p><img src="https://user-images.githubusercontent.com/1342360/82240467-62030100-9932-11ea-8db9-917f2d977fe1.png" alt="image" /></p>
<p>Still, it's probably worth investigating why we're getting users from the database that often, and whether it's possible to reduce the amount of queries we make by adjusting our cache factor(s).</p>
<p>The <code>persist_events</code> transaction is responsible for saving new room events to the Synapse database, so can often show a high transaction duration.</p>
<h2 id="federation"><a class="header" href="#federation">Federation</a></h2>
<p>The charts in the "Federation" section show information about incoming and outgoing federation requests. Federation data can be divided into two basic types:</p>
<ul>
<li>PDU (Persistent Data Unit) - room events: messages, state events (join/leave), etc. These are permanently stored in the database.</li>
<li>EDU (Ephemeral Data Unit) - other data, which need not be stored permanently, such as read receipts, typing notifications.</li>
</ul>
<p>The "Outgoing EDUs by type" chart shows the EDUs within outgoing federation requests by type: <code>m.device_list_update</code>, <code>m.direct_to_device</code>, <code>m.presence</code>, <code>m.receipt</code>, <code>m.typing</code>.</p>
<p>If you see a large number of <code>m.presence</code> EDUs and are having trouble with too much CPU load, you can disable <code>presence</code> in the Synapse config. See also <a href="https://github.com/matrix-org/synapse/issues/3971">#3971</a>.</p>
<h2 id="caches"><a class="header" href="#caches">Caches</a></h2>
<p><img src="https://user-images.githubusercontent.com/1342360/82240572-8b239180-9932-11ea-96ff-6b5f0e57ebe5.png" alt="image" /></p>
<p><img src="https://user-images.githubusercontent.com/1342360/82240666-b8703f80-9932-11ea-86af-9f663988d8da.png" alt="image" /></p>
<p>This is quite a useful graph. It shows how many times Synapse attempts to retrieve a piece of data from a cache which the cache did not contain, thus resulting in a call to the database. We can see here that the <code>_get_joined_profile_from_event_id</code> cache is being requested a lot, and often the data we're after is not cached.</p>
<p>Cross-referencing this with the Eviction Rate graph, which shows that entries are being evicted from <code>_get_joined_profile_from_event_id</code> quite often:</p>
<p><img src="https://user-images.githubusercontent.com/1342360/82240766-de95df80-9932-11ea-8c15-5acfc57c48da.png" alt="image" /></p>
<p>we should probably consider raising the size of that cache by raising its cache factor (a multiplier value for the size of an individual cache). Information on doing so is available <a href="https://github.com/matrix-org/synapse/blob/ee421e524478c1ad8d43741c27379499c2f6135c/docs/sample_config.yaml#L608-L642">here</a> (note that the configuration of individual cache factors through the configuration file is available in Synapse v1.14.0+, whereas doing so through environment variables has been supported for a very long time). Note that this will increase Synapse's overall memory usage.</p>
<h2 id="forward-extremities"><a class="header" href="#forward-extremities">Forward Extremities</a></h2>
<p><img src="https://user-images.githubusercontent.com/1342360/82241440-13566680-9934-11ea-8b88-ba468db937ed.png" alt="image" /></p>
<p>Forward extremities are the leaf events at the end of a DAG in a room, aka events that have no children. The more that exist in a room, the more <a href="https://spec.matrix.org/v1.1/server-server-api/#room-state-resolution">state resolution</a> that Synapse needs to perform (hint: it's an expensive operation). While Synapse has code to prevent too many of these existing at one time in a room, bugs can sometimes make them crop up again.</p>
<p>If a room has >10 forward extremities, it's worth checking which room is the culprit and potentially removing them using the SQL queries mentioned in <a href="https://github.com/matrix-org/synapse/issues/1760">#1760</a>.</p>
<h2 id="garbage-collection"><a class="header" href="#garbage-collection">Garbage Collection</a></h2>
<p><img src="https://user-images.githubusercontent.com/1342360/82241911-da6ac180-9934-11ea-9a0d-a311fe22acd0.png" alt="image" /></p>
<p>Large spikes in garbage collection times (bigger than shown here, I'm talking in the
multiple seconds range), can cause lots of problems in Synapse performance. It's more an
indicator of problems, and a symptom of other problems though, so check other graphs for what might be causing it.</p>
<h2 id="final-thoughts"><a class="header" href="#final-thoughts">Final Thoughts</a></h2>
<p>If you're still having performance problems with your Synapse instance and you've
tried everything you can, it may just be a lack of system resources. Consider adding
more CPU and RAM, and make use of <a href="../../workers.html">worker mode</a>
to make use of multiple CPU cores / multiple machines for your homeserver.</p>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="../../usage/administration/monthly_active_users.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="../../usage/administration/useful_sql_for_admins.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
<a rel="prev" href="../../usage/administration/monthly_active_users.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="../../usage/administration/useful_sql_for_admins.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
</nav>
</div>
<script type="text/javascript">
window.playground_copyable = true;
</script>
<script src="../../elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
<script src="../../mark.min.js" type="text/javascript" charset="utf-8"></script>
<script src="../../searcher.js" type="text/javascript" charset="utf-8"></script>
<script src="../../clipboard.min.js" type="text/javascript" charset="utf-8"></script>
<script src="../../highlight.js" type="text/javascript" charset="utf-8"></script>
<script src="../../book.js" type="text/javascript" charset="utf-8"></script>
<!-- Custom JS scripts -->
<script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
</body>
</html>
|
