diff options
Diffstat (limited to 'lib/kernel/doc/src/error_logger.xml')
| -rw-r--r-- | lib/kernel/doc/src/error_logger.xml | 48 |
1 files changed, 19 insertions, 29 deletions
diff --git a/lib/kernel/doc/src/error_logger.xml b/lib/kernel/doc/src/error_logger.xml index c9fe9484e4..e91fc734a4 100644 --- a/lib/kernel/doc/src/error_logger.xml +++ b/lib/kernel/doc/src/error_logger.xml @@ -36,41 +36,31 @@ <p>In OTP-21, a new API for logging was added to Erlang/OTP. The old <c>error_logger</c> module can still be used by legacy code, but new code should use the new API instead.</p> + <p><c>error_logger</c> is no longer started by default, but is + automatically started when an event handler is added + with <c>error_logger:add_report_handler/1,2</c>. The <c>error_logger</c> + module is then also added as a handler to the new logger.</p> <p>See <seealso marker="logger"><c>logger(3)</c></seealso> and the <seealso marker="logger_chapter">Logging</seealso> chapter - in the user's guide for more information.</p> + in the User's Guide for more information.</p> </note> <p>The Erlang <em>error logger</em> is an event manager (see <seealso marker="doc/design_principles:des_princ">OTP Design Principles</seealso> and <seealso marker="stdlib:gen_event"><c>gen_event(3)</c></seealso>), - registered as <c>error_logger</c>. Errors, warnings, and info events - are sent to the error logger from the Erlang runtime system and - the different Erlang/OTP applications. The events are, by default, - logged to the terminal. Notice that an event from a process <c>P</c> is - logged at the node of the group leader of <c>P</c>. This means - that log output is directed to the node from which a process was - created, which not necessarily is the same node as where it is - executing.</p> - <p>Initially, <c>error_logger</c> has only a primitive event - handler, which buffers and prints the raw event messages. During - system startup, the Kernel application replaces this with a - <em>standard event handler</em>, by default one that writes - nicely formatted output to the terminal. Kernel can also be - configured so that events are logged to a file instead, or not logged at all, - see <seealso marker="kernel_app"><c>kernel(6)</c></seealso>.</p> - <p>Also the SASL application, if started, adds its own event - handler, which by default writes supervisor, crash, and progress - reports to the terminal. See - <seealso marker="sasl:sasl_app"><c>sasl(6)</c></seealso>.</p> - <p>It is recommended that user-defined applications report - errors through the error logger to get uniform reports. - User-defined event handlers can be added to handle application-specific - events, see - <seealso marker="#add_report_handler/1"><c>add_report_handler/1,2</c></seealso>. - Also, a useful event handler is provided in STDLIB for multi-file - logging of events, see - <seealso marker="stdlib:log_mf_h"><c>log_mf_h(3)</c></seealso>.</p> + registered as <c>error_logger</c>.</p> + <p>Error logger is no longer started by default, but is + automatically started when an event handler is added + with <seealso marker="#add_report_handler/1"> + <c>add_report_handler/1,2</c></seealso>. The <c>error_logger</c> + module is then also added as a handler to the new logger, + causing log events to be forwarded from logger to error logger, + and consequently to all installed error logger event + handlers.</p> + <p>User-defined event handlers can be added to handle application-specific + events.</p> + <p>Existing event handlers provided by STDLIB and SASL are still + available, but are no longer used by OTP.</p> <p>Warning events were introduced in Erlang/OTP R9C and are enabled by default as from Erlang/OTP 18.0. To retain backwards compatibility with existing user-defined event handlers, the warning events can be @@ -191,7 +181,7 @@ ok</pre> <p>The <c>error_logger_format_depth</c> variable is <seealso marker="kernel_app#deprecated-configuration-parameters"> deprecated</seealso> since - the <seealso marker="logger">Logger API</seealso> was + the <seealso marker="logger">logging API</seealso> was introduced in OTP-21. The variable, and this function, are kept for backwards compatibility since they still might be used by legacy report handlers.</p> |