glog/docs/log_stripping.md

Strip Logging Messages

Strings used in log messages can increase the size of your binary and present a privacy concern. You can therefore instruct glog to remove all strings which fall below a certain severity level by using the GOOGLE_STRIP_LOG macro:

If your application has code like this:

#define GOOGLE_STRIP_LOG 1    // this must go before the #include!
#include <glog/logging.h>

The compiler will remove the log messages whose severities are less than the specified integer value. Since VLOG logs at the severity level INFO (numeric value 0), setting GOOGLE_STRIP_LOG to 1 or greater removes all log messages associated with VLOGs as well as INFO log statements.