man Log::Log4perl::Appender::Limit () - Limit message delivery via block period


    Log::Log4perl::Appender::Limit - Limit message delivery via block period


    use Log::Log4perl qw(:easy);

    my $conf = qq(
      log4perl.category = WARN, Limiter

          # Email appender
      log4perl.appender.Mailer          = Log::Dispatch::Email::MailSend       = drone\
      log4perl.appender.Mailer.subject  = Something's broken!
      log4perl.appender.Mailer.buffered = 0
      log4perl.appender.Mailer.layout   = PatternLayout
      log4perl.appender.Mailer.layout.ConversionPattern=%d %m %n

          # Limiting appender, using the email appender above
      log4perl.appender.Limiter              = Log::Log4perl::Appender::Limit
      log4perl.appender.Limiter.appender     = Mailer
      log4perl.appender.Limiter.block_period = 3600

    WARN("This message will be sent immediately");
    WARN("This message will be delayed by one hour.");
    WARN("This message plus the last one will be sent now");


Specifies the name of the appender used by the limiter. The appender specified must be defined somewhere in the configuration file, not necessarily before the definition of CWLog::Log4perl::Appender::Limit. Period in seconds between delivery of messages. If messages arrive in between, they will be either saved (if CWaccumulate is set to a true value) or discarded (if CWaccumulate isn't set). File name in which CWLog::Log4perl::Appender::Limit persistently stores delivery times. If omitted, the appender will have no recollection of what happened when the program restarts. Maximum number of accumulated messages. If exceeded, the appender flushes all messages, regardless if the interval set in CWblock_period has passed or not. Don't mix with CWmax_until_discarded. Maximum number of accumulated messages. If exceeded, the appender will simply discard additional messages, waiting for CWblock_period to expire to flush all accumulated messages. Don't mix with CWmax_until_flushed.

If the appender attached to CWLimit uses CWPatternLayout with a timestamp specifier, you will notice that the message timestamps are reflecting the original log event, not the time of the message rendering in the attached appender. Major trickery has applied to accomplish this (Cough!).


CWLog::Log4perl::Appender::Limit is a composite appender. Unlike other appenders, it doesn't log any messages, it just passes them on to its attached sub-appender. For this reason, it doesn't need a layout (contrary to regular appenders). If it defines none, messages are passed on unaltered.

Custom filters are also applied to the composite appender only. They are not applied to the sub-appender. Same applies to appender thresholds. This behaviour might change in the future.


Copyright 2004 by Mike Schilli, all rights reserved. This program is free software, you can redistribute it and/or modify it under the same terms as Perl itself.


2004, Mike Schilli <>