tree: a89e9014712f94fa04157e341c9dfecc35905690 [path history] [tgz]
  1. .gitignore
  2. CMakeLists.txt
  7. cmake/
  8. include/


Very fast, header only, C++ logging library. Build Status  Build status


Just copy the headers:

  • Copy the source folder to your build tree and use a C++11 compiler.

Or use your favourite package manager:

  • Ubuntu: apt-get install libspdlog-dev
  • Homebrew: brew install spdlog
  • FreeBSD: cd /usr/ports/devel/spdlog/ && make install clean
  • Fedora: yum install spdlog
  • Arch Linux: pacman -S spdlog-git
  • vcpkg: vcpkg install spdlog


  • Linux, FreeBSD, Solaris
  • Windows (vc 2013+, cygwin/mingw)
  • Mac OSX (clang 3.5+)
  • Android


  • Very fast - performance is the primary goal (see benchmarks below).
  • Headers only, just copy and use.
  • Feature rich call style using the excellent fmt library.
  • Extremely fast asynchronous mode (optional) - using lockfree queues and other tricks to reach millions of calls/sec.
  • Custom formatting.
  • Conditional Logging
  • Multi/Single threaded loggers.
  • Various log targets:
    • Rotating log files.
    • Daily log files.
    • Console logging (colors supported).
    • syslog.
    • Windows debugger (OutputDebugString(..))
    • Easily extendable with custom log targets (just implement a single function in the sink interface).
  • Severity based filtering - threshold levels can be modified in runtime as well as in compile time.


Below are some benchmarks comparing popular log libraries under Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz

Synchronous mode

Time needed to log 1,000,000 lines in synchronous mode (in seconds, the best of 3 runs):

threadsboost log 1.54glogeasyloggingspdlog

Asynchronous mode

Time needed to log 1,000,000 lines in asynchronous mode, i.e. the time it takes to put them in the async queue (in seconds, the best of 3 runs):

threadsg2log async loggerspdlog async mode

Usage Example

#include "spdlog/spdlog.h" #include <iostream> #include <memory> void async_example(); void syslog_example(); void user_defined_example(); void err_handler_example(); namespace spd = spdlog; int main(int, char*[]) { try { // Console logger with color auto console = spd::stdout_color_mt("console"); console->info("Welcome to spdlog!"); console->error("Some error message with arg{}..", 1); // Conditional logging example auto i = 2; console->warn_if(i != 0, "an important message"); // Formatting examples console->warn("Easy padding in numbers like {:08d}", 12); console->critical("Support for int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}", 42); console->info("Support for floats {:03.2f}", 1.23456); console->info("Positional args are {1} {0}..", "too", "supported"); console->info("{:<30}", "left aligned"); spd::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name) function"); // Create basic file logger (not rotated) auto my_logger = spd::basic_logger_mt("basic_logger", "logs/basic.txt"); my_logger->info("Some log message"); // Create a file rotating logger with 5mb size max and 3 rotated files auto rotating_logger = spd::rotating_logger_mt("some_logger_name", "logs/mylogfile", 1048576 * 5, 3); for (int i = 0; i < 10; ++i) rotating_logger->info("{} * {} equals {:>10}", i, i, i*i); // Create a daily logger - a new file is created every day on 2:30am auto daily_logger = spd::daily_logger_mt("daily_logger", "logs/daily", 2, 30); // trigger flush if the log severity is error or higher daily_logger->flush_on(spd::level::err); daily_logger->info(123.44); // Customize msg format for all messages spd::set_pattern("*** [%H:%M:%S %z] [thread %t] %v ***"); rotating_logger->info("This is another message with custom format"); // Runtime log levels spd::set_level(spd::level::info); //Set global log level to info console->debug("This message shold not be displayed!"); console->set_level(spd::level::debug); // Set specific logger's log level console->debug("This message shold be displayed.."); // Compile time log levels // define SPDLOG_DEBUG_ON or SPDLOG_TRACE_ON SPDLOG_TRACE(console, "Enabled only #ifdef SPDLOG_TRACE_ON..{} ,{}", 1, 3.23); SPDLOG_DEBUG(console, "Enabled only #ifdef SPDLOG_DEBUG_ON.. {} ,{}", 1, 3.23); // Asynchronous logging is very fast.. // Just call spdlog::set_async_mode(q_size) and all created loggers from now on will be asynchronous.. async_example(); // syslog example. linux/osx only syslog_example(); // android example. compile with NDK android_example(); // Log user-defined types example user_defined_example(); // Change default log error handler err_handler_example(); // Apply a function on all registered loggers spd::apply_all([&](std::shared_ptr<spd::logger> l) { l->info("End of example."); }); // Release and close all loggers spd::drop_all(); } // Exceptions will only be thrown upon failed logger or sink construction (not during logging) catch (const spd::spdlog_ex& ex) { std::cout << "Log init failed: " << ex.what() << std::endl; return 1; } } void async_example() { size_t q_size = 4096; //queue size must be power of 2 spd::set_async_mode(q_size); auto async_file = spd::daily_logger_st("async_file_logger", "logs/async_log.txt"); for (int i = 0; i < 100; ++i) async_file->info("Async message #{}", i); } //syslog example void syslog_example() { #ifdef SPDLOG_ENABLE_SYSLOG std::string ident = "spdlog-example"; auto syslog_logger = spd::syslog_logger("syslog", ident, LOG_PID); syslog_logger->warn("This is warning that will end up in syslog.."); #endif } // user defined types logging by implementing operator<< struct my_type { int i; template<typename OStream> friend OStream& operator<<(OStream& os, const my_type &c) { return os << "[my_type i="<<c.i << "]"; } }; #include <spdlog/fmt/ostr.h> // must be included void user_defined_example() { spd::get("console")->info("user defined type: {}", my_type { 14 }); } // //custom error handler // void err_handler_example() { spd::set_error_handler([](const std::string& msg) { std::cerr << "my err handler: " << msg << std::endl; }); // (or logger->set_error_handler(..) to set for specific logger) }


Documentation can be found in the wiki pages.