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authorSiri Hansen <[email protected]>2018-12-14 13:05:32 +0100
committerSiri Hansen <[email protected]>2019-01-16 09:59:24 +0100
commit6211cead7be6f0871cfcccccdfc00dbeb466bcf2 (patch)
tree887402465f8a581a83006df906d44668a1baa7ab /lib/kernel/doc/src/logger_chapter.xml
parent2c63eda781ccf12c2f35a94bc07b1b1013232483 (diff)
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[logger] Add API function for configuring logger proxy
Diffstat (limited to 'lib/kernel/doc/src/logger_chapter.xml')
-rw-r--r--lib/kernel/doc/src/logger_chapter.xml55
1 files changed, 53 insertions, 2 deletions
diff --git a/lib/kernel/doc/src/logger_chapter.xml b/lib/kernel/doc/src/logger_chapter.xml
index 458e61cef5..5ed7397135 100644
--- a/lib/kernel/doc/src/logger_chapter.xml
+++ b/lib/kernel/doc/src/logger_chapter.xml
@@ -693,8 +693,10 @@ logger:debug(#{got => connection_request, id => Id, state => State},
with <seealso marker="#logger_sasl_compatible">
<c>logger_sasl_compatible</c></seealso>.</p>
<p>With this parameter, you can modify or disable the default
- handler, add custom handlers and primary logger filters, and
- set log levels per module.</p>
+ handler, add custom handlers and primary logger filters, set
+ log levels per module, and modify
+ the <seealso marker="#proxy">proxy</seealso>
+ configuration.</p>
<p><c>Config</c> is any (zero or more) of the following:</p>
<taglist>
<tag><c>{handler, default, undefined}</c></tag>
@@ -746,6 +748,14 @@ logger:debug(#{got => connection_request, id => Id, state => State},
<p>for each <c>Module</c>.</p>
<p>Multiple entries of this type are allowed.</p>
</item>
+ <tag><c>{proxy, ProxyConfig}</c></tag>
+ <item>
+ <p>Sets the proxy configuration, equivalent to calling</p>
+ <pre><seealso marker="logger#set_proxy_config/1">
+ logger:set_proxy_config(ProxyConfig)
+ </seealso></pre>
+ <p>Only one entry of this type is allowed.</p>
+ </item>
</taglist>
<p>See
section <seealso marker="#config_examples">Configuration
@@ -1334,9 +1344,50 @@ logger:add_handler(my_disk_log_h, logger_disk_log_h,
</section>
<section>
+ <marker id="proxy"/>
+ <title>Logger Proxy</title>
+ <p>The Logger proxy is an Erlang process which is part of the
+ Kernel application's supervision tree. During startup, the proxy
+ process registers itself as the <c>system_logger</c>, meaning
+ that log events produced by the emulator are sent to this
+ process.</p>
+ <p>When a log event is issued on a process which has its group
+ leader on a remote node, Logger automatically forwards the log
+ event to the group leader's node. To achieve this, it first
+ sends the log event as an Erlang message from the original
+ client process to the proxy on the local node, and the proxy in
+ turn forwards the event to the proxy on the remote node.</p>
+ <p>When receiving a log event, either from the emulator or from a
+ remote node, the proxy calls the Logger API to log the event.</p>
+ <p>The proxy process is overload protected in the same way as
+ described in
+ section <seealso marker="#overload_protection">Protecting the
+ Handler from Overload</seealso>, but with the following default
+ values:</p>
+ <code>
+ #{sync_mode_qlen => 500,
+ drop_mode_qlen => 1000,
+ flush_qlen => 5000,
+ burst_limit_enable => false,
+ overload_kill_enable => false}</code>
+ <p>For log events from the emulator, synchronous message passing
+ mode is not applicable, since all messages are passed
+ asynchronously by the emulator. Drop mode is achieved by setting
+ the <c>system_logger</c> to <c>undefined</c>, forcing the
+ emulator to drop events until it is set back to the proxy pid
+ again.</p>
+ <p>The proxy uses <seealso marker="erts:erlang#send_nosuspend/2">
+ <c>erlang:send_nosuspend/2</c></seealso> when sending log
+ events to a remote node. If the message could not be sent
+ without suspending the sender, it is dropped. This is to avoid
+ blocking the proxy process.</p>
+ </section>
+
+ <section>
<title>See Also</title>
<p>
<seealso marker="disk_log"><c>disk_log(3)</c></seealso>,
+ <seealso marker="erts:erlang"><c>erlang(3)</c></seealso>,
<seealso marker="error_logger"><c>error_logger(3)</c></seealso>,
<seealso marker="logger"><c>logger(3)</c></seealso>,
<seealso marker="logger_disk_log_h"><c>logger_disk_log_h(3)</c></seealso>,