[boost] [log] filtering performance

From: Igor Nazarenko (igor.n.nazarenko_at_[hidden])
Date: 2008-09-01 01:59:17

It seems that the library does quite a bit of work before filtering
away a record, unless the logging is turned off entirely. There's at
least two mutex locks, some memory allocation, etc. Callgrind claims
~2500 instructions when the record is thrown away by the global
severity filter. Shortened callgrind output is in-line below; full
output and the test program attached. Compiled by gcc 4.2.3 using
boost.build variant=release threading=multi.

 7      BOOST_LOG_SEV(slg, normal) << "A normal severity message, will
not pass to the output (global filter)";
99,557  => bool basic_severity_logger::open_record() (1x)
 7      BOOST_LOG_SEV(slg, normal) << "A normal severity message, will
not pass to the output (global filter)";
2,530   => bool basic_severity_logger::open_record() (1x)
 7      BOOST_LOG_SEV(slg, normal) << "A normal severity message, will
not pass to the output (global filter)";
2,530   => bool basic_severity_logger::open_record() (1x)

 7      BOOST_LOG_SEV(slg, warning) << "An warning severity message,
will not pass to the output (sink filter)";
5,212   => bool basic_severity_logger::open_record() (1x)
 7      BOOST_LOG_SEV(slg, warning) << "An warning severity message,
will not pass to the output (sink filter)";
3,904   => bool basic_severity_logger::open_record() (1x)
 7      BOOST_LOG_SEV(slg, warning) << "An warning severity message,
will not pass to the output (sink filter)";
3,904   => bool basic_severity_logger::open_record() (1x)
 .
10      BOOST_LOG_SEV(slg, error) << "An error severity message, will
be printed";
218,306 => record_pump::~record_pump() (1x)
24,144  => bool basic_severity_logger::open_record() (1x)
10      BOOST_LOG_SEV(slg, error) << "An error severity message, will
be printed";
28,963  => record_pump::~record_pump() (1x)
5,074   => bool basic_severity_logger::open_record() (1x)
11      BOOST_LOG_SEV(slg, error) << "An error severity message, will
be printed";
28,644  => record_pump::~record_pump() (1x)
5,074   => bool basic_severity_logger::open_record() (1x)