Quill

Ultra-Low-Latency Asynchronous C++17 Logging and Metrics Library

🔬 Try It Online · 🚀 Benchmarks · 📚 Documentation · ⚡ Recipes · ❓ FAQ
🐛 Report Bug · 💡 Request Feature

🧭 Table of Contents

Introduction
Quick Start
Features
Performance
Usage
Design
Caveats
License

✨ Introduction

Quill is an asynchronous logging and metrics library for C++17 and later. It keeps formatting and I/O away from latency-sensitive application threads by encoding log arguments on the frontend and processing them on a dedicated backend worker.

Low Frontend Latency: Log arguments are encoded and queued for asynchronous processing, minimizing work on the calling thread. See the latency benchmarks for measured results and methodology.
Deferred Formatting: Expensive formatting is performed by the backend worker instead of the calling thread.
Logging and Metrics: Publish pre-registered metrics through the same asynchronous backend. The bundled Prometheus sink handles common metric types, while custom sinks can route samples to StatsD, OpenTelemetry, or other collectors. See the Metrics guide.
Highly Customizable: Tune frontend queues and memory policy at compile time; configure backend idle behaviour, CPU affinity, buffering, timestamp handling, flushing, and callbacks at runtime; and compose loggers from built-in or custom sinks with per-sink filters. See Frontend Options, Backend Options, and Sinks.
Production-Focused Testing: Continuously tested across Linux, macOS, Windows, and BSD, with sanitizers and fuzzing.

Using Quill? Click Star at the top of the GitHub repository to help other C++ developers discover it.

⏩ Quick Start

Getting started is easy and straightforward. Follow these steps to integrate the library into your project:

Installation

You can install Quill using the package manager of your choice:

Package Manager	Installation Command
vcpkg	`vcpkg install quill`
Conan	`conan install quill`
Homebrew	`brew install quill`
Meson WrapDB	`meson wrap install quill`
Conda	`conda install -c conda-forge quill`
Bzlmod	`bazel_dep(name = "quill", version = "x.y.z")`
xmake	`xrepo install quill`
nix	`nix-shell -p quill-log`
build2	`libquill`

Setup

Quickest Setup

For the shortest path from zero to working logs, use simple_logger():

#include "quill/SimpleSetup.h"
#include "quill/LogMacros.h"

int main()
{
  // log to the console
  auto* logger = quill::simple_logger();
  LOG_INFO(logger, "Hello from {}!", "Quill");

  // log to a file
  auto* logger2 = quill::simple_logger("test.log");
  LOG_WARNING(logger2, "This message goes to a file");
}

Console output:

20:07:18.423476231 [48917] main.cpp:8                    LOG_INFO      Hello from Quill!

Detailed Setup

If you want explicit control over backend options, logger names, sinks, or formatters, use the Backend and Frontend APIs directly:

#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/ConsoleSink.h"
#include <string_view>

int main()
{
  quill::Backend::start();

  quill::Logger* logger = quill::Frontend::create_or_get_logger(
    "root", quill::Frontend::create_or_get_sink<quill::ConsoleSink>("sink_id_1"));

  LOG_INFO(logger, "Hello from {}!", std::string_view{"Quill"});
}

Output:

20:07:18.423476231 [48917] main.cpp:15                   LOG_INFO      root         Hello from Quill!

You can also use the macro-free mode. The macro API (LOG_INFO) is the lowest-latency path. The function API (quill::info) reads more like ordinary code but is slightly slower. See here for the trade-offs.

#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogFunctions.h"
#include "quill/Logger.h"
#include "quill/sinks/ConsoleSink.h"
#include <string_view>

int main()
{
  quill::Backend::start();

  quill::Logger* logger = quill::Frontend::create_or_get_logger(
    "root", quill::Frontend::create_or_get_sink<quill::ConsoleSink>("sink_id_1"));

  quill::info(logger, "Hello from {}!", std::string_view{"Quill"});
}

Publishing Metrics

Register MetricMetadata once, then publish double samples from hot threads through the same asynchronous backend used for logs. The bundled PrometheusSink handles counters, gauges, histograms, and summaries; custom sinks can route samples to StatsD, OpenTelemetry, or any in-process collector via Sink::write_metric().

// One-time registration — returns a stable pointer valid for program lifetime.
quill::MetricMetadata const* requests_total = quill::Frontend::create_metric(
  "requests_total_post_200", "requests_total", {{"method", "POST"}, {"status", "200"}});

// Hot path — no label serialization, just a pointer and a double.
logger->publish_metric(requests_total, 1.0);

See the Metrics guide for sink setup, custom sinks, and Prometheus integration.

🎯 Features

High-Performance: Ultra-low latency performance.
Asynchronous Processing: Background thread handles formatting and I/O, keeping your main thread responsive.
Metric Publishing: Publish pre-registered metric samples to Prometheus, StatsD, OpenTelemetry, or any in-process collector through the same asynchronous backend. See Metrics.
Minimal Header Includes:
- Frontend: Only Logger.h and LogMacros.h needed for logging. Lightweight with minimal dependencies.
- Backend: Single .cpp file inclusion. No backend code injection into other translation units.
Compile-Time Optimization: Eliminate specific log levels at compile time.
Custom Formatters: Define your own log output patterns. See Formatters.
Cross-Thread Timestamp Handling: The backend compares available events across frontend queues by timestamp, with a configurable grace window for delayed producers and optional sink-visible monotonic timestamp correction. See Timestamp Types.
Flexible Timestamps: Support for rdtsc, chrono, or custom clocks - ideal for simulations and more.
Backtrace Logging: Store messages in a ring buffer for on-demand display. See Backtrace Logging
Multiple Output Sinks: Console (with color), files (with rotation), JSON, ability to create custom sinks and more.
Log Filtering: Process only relevant messages. See Filters.
JSON Logging: Structured log output. See JSON Logging
Mapped Diagnostic Context (MDC): Thread-local key/value context attached automatically to subsequent log lines. See MDC.
Rate-Limited Macros: LOG_*_LIMIT / LOGV_*_LIMIT emit at most once per configured interval per call site.
Configurable Queue Modes: bounded/unbounded and blocking/dropping options with monitoring on dropped messages, queue reallocations, and blocked hot threads.
Crash Handling: Built-in signal handler for log preservation during crashes.
Huge Pages Support (Linux): Leverage huge pages on the hot path for optimized performance.
Wide Character Support (Windows): Logs wide strings by converting them to UTF-8 on the backend, with support for STL containers consisting of wide strings.
Exception-Free Option: Configurable builds with or without exception handling.
Clean Codebase: Maintained to high standards, warning-free even at strict levels.
Type-Safe API: Built on {fmt} library.

🚀 Performance

System Configuration

OS: Linux RHEL 9.4
CPU: Intel Core i5-12600 (12th Gen) @ 4.8 GHz
Compiler: GCC 14.2
Build: Release with -march=x86-64-v3
Benchmark-Tuned System: The system is specifically tuned for benchmarking.

Command Line Parameters:

$ cat /proc/cmdline
BOOT_IMAGE=(hd0,gpt2)/vmlinuz-5.14.0-427.13.1.el9_4.x86_64 root=/dev/mapper/rhel-root ro crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet nohz=on nohz_full=1-5 rcu_nocbs=1-5 isolcpus=1-5 mitigations=off transparent_hugepage=never intel_pstate=disable nosoftlockup irqaffinity=0 processor.max_cstate=1 nosoftirqd sched_tick_offload=0 spec_store_bypass_disable=off spectre_v2=off iommu=pt

You can find the benchmark code on the logger_benchmarks repository.

Latency

The results presented in the tables below are measured in nanoseconds (ns).

The tables are sorted by the 90th percentile (lower is better).

Logging Numbers

LOG_INFO(logger, "Logging int: {}, int: {}, double: {}", i, j, d).

1 Thread Logging

Library	50th	75th	90th	95th	99th	99.9th
Quill Unbounded Queue	6	6	6	7	8	10
fmtlog	6	6	6	7	8	10
Quill Bounded Dropping Queue	6	6	6	7	9	10
XTR	6	6	6	7	9	11
PlatformLab NanoLog	8	8	9	10	10	11
MS BinLog	18	18	19	19	73	119
Quill Unbounded Queue (Log Functions)	25	26	27	28	29	34
Reckless	26	28	31	33	35	47
BqLog	124	132	138	141	153	186
Iyengar NanoLog	106	116	154	163	386	477
spdlog	273	283	299	314	338	360
g3log	1063	1078	1091	1100	1115	1134
Boost.Log	3072	3132	3334	3367	3535	3706

4 Threads Logging Simultaneously

Library	50th	75th	90th	95th	99th	99.9th
Quill Unbounded Queue	8	8	8	8	12	20
Quill Bounded Dropping Queue	8	8	8	8	17	19
XTR	8	8	8	15	17	20
fmtlog	8	9	9	9	11	15
PlatformLab NanoLog	14	15	15	15	16	22
MS BinLog	29	30	31	33	253	450
Quill Unbounded Queue (Log Functions)	33	35	39	42	48	57
Reckless	27	37	44	47	59	89
Iyengar NanoLog	72	77	261	279	354	1406
BqLog	110	391	407	416	445	621
spdlog	562	590	619	643	711	1050
g3log	1175	1295	1397	1476	1600	1762
Boost.Log	1624	2795	3146	3194	4249	5358

Logging Large Strings

Logging std::string over 35 characters to prevent the short string optimization.

LOG_INFO(logger, "Logging int: {}, int: {}, string: {}", i, j, large_string).

1 Thread Logging

Library	50th	75th	90th	95th	99th	99.9th
fmtlog	8	8	9	10	11	13
XTR	7	8	9	10	12	16
PlatformLab NanoLog	11	11	12	13	14	15
Quill Bounded Dropping Queue	9	10	12	13	16	19
Quill Unbounded Queue	10	11	13	15	16	19
MS BinLog	19	20	22	23	77	122
Quill Unbounded Queue (Log Functions)	29	31	32	33	35	38
Reckless	87	102	110	113	120	135
BqLog	127	136	143	150	163	189
Iyengar NanoLog	105	115	154	162	383	455
spdlog	234	242	250	255	267	281
g3log	833	842	850	855	866	885
Boost.Log	2879	3110	3149	3179	3278	3485

4 Threads Logging Simultaneously

Library	50th	75th	90th	95th	99th	99.9th
fmtlog	9	9	13	14	19	25
Quill Bounded Dropping Queue	8	9	14	16	23	34
Quill Unbounded Queue	9	9	15	16	22	26
XTR	9	10	16	17	21	27
PlatformLab NanoLog	15	17	19	21	23	32
MS BinLog	30	30	33	36	254	452
Quill Unbounded Queue (Log Functions)	36	40	45	49	55	68
Reckless	37	74	127	140	159	180
Iyengar NanoLog	74	88	279	294	475	1457
BqLog	118	395	413	426	475	642
spdlog	531	555	583	608	671	992
g3log	940	1045	1103	1224	1355	1476
Boost.Log	1340	2563	2923	2963	4078	5107

Logging Complex Types

Logging std::vector<std::string> containing 16 large strings, each ranging from 50 to 60 characters.

Note: some of the previous loggers do not support passing a std::vector as an argument.

LOG_INFO(logger, "Logging int: {}, int: {}, vector: {}", i, j, v).

1 Thread Logging

Library	50th	75th	90th	95th	99th	99.9th
Quill Bounded Dropping Queue	49	53	57	60	66	101
MS BinLog	61	63	65	67	73	369
Quill Unbounded Queue	117	127	136	140	149	157
XTR	760	802	839	861	908	980
fmtlog	785	823	858	879	921	969
Boost.Log	4191	4302	4374	4463	4633	4968
spdlog	6825	6942	7090	7291	7696	8110

4 Threads Logging Simultaneously

Library	50th	75th	90th	95th	99th	99.9th
Quill Bounded Dropping Queue	65	73	86	96	111	125
MS BinLog	72	78	87	98	305	549
Quill Unbounded Queue	77	86	99	108	125	143
fmtlog	677	704	730	745	774	806
XTR	684	728	777	802	844	873
Boost.Log	2679	3616	4639	4823	5826	7855
spdlog	6954	7158	7388	7599	8369	9896

The benchmark methodology involves logging 20 messages in a loop, calculating and storing the average latency for those 20 messages, then waiting around ~2 milliseconds, and repeating this process for a specified number of iterations.

In the Quill Bounded Dropping benchmarks, the dropping queue size is set to 262,144 bytes, which is double the default size of 131,072 bytes.

Throughput

Throughput is measured by calculating the maximum number of log messages the backend logging thread can write to a log file per second (higher is better).

The tests were run on the same system used for the latency benchmarks.

Although Quill’s primary focus is not on maximizing throughput, it efficiently manages log messages across multiple threads. Benchmarking throughput of asynchronous logging libraries presents certain challenges. Some libraries may drop log messages, leading to smaller-than-expected log files, while others only provide asynchronous flushing, making it difficult to verify when the backend thread has fully processed all messages.

For comparison, we benchmark against other asynchronous logging libraries that offer guaranteed logging with a flush-and-wait mechanism.

Note that MS BinLog writes log data to a binary file, which requires offline formatting with an additional program—this makes it an unfair comparison, but it is included for reference.

Similarly, BqLog (binary log) uses the compressed binary log appender, and its log files are not human-readable unless processed offline. However, it is included for reference. The other version of BqLog is using a text appender and produces human-readable log files.

In the same way, Platformlab Nanolog also outputs binary logs and is expected to deliver high throughput. However, for reasons unexplained, the benchmark runs significantly slower (10x longer) than the other libraries, so it is excluded from the table.

XTR uses FMT_COMPILE for message formatting in this benchmark. Quill does not currently use that optimisation: decoded arguments are formatted through the runtime fmt APIs, and the final log line then passes through Quill's runtime-configurable PatternFormatter.

Logging 4 million times the message "Iteration: {} int: {} double: {}"

Library	million msg/second	elapsed time
MS BinLog (binary log)	63.39	63 ms
BqLog (binary log)	13.16	303 ms
XTR	7.68	521 ms
BqLog	5.45	733 ms
Quill	4.97	804 ms
spdlog	2.66	1504 ms
fmtlog	2.65	1510 ms
Reckless	2.58	1551 ms
Quill - Macro Free Mode	2.33	1717 ms
Boost.Log	0.33	12212 ms

Compilation Time

Compile times are measured on the system above using clean Release builds of BENCHMARK_quill_compile_time, which compiles 2000 auto-generated log statements with varied argument types.

The measurements below were taken with -march=x86-64-v3 for Release, running one clean build at a time with -j4. Clang builds additionally enable -ftime-trace.

Quill intentionally keeps call-site metadata such as file, line, format string, and tags out of the frontend template identity. In the common macro-based path, that information is stored in a MacroMetadata object and passed as a regular function argument. As a result, multiple log statements with the same argument type pack can reuse the same log_statement instantiation; changing only the call-site metadata does not create a new frontend template instantiation.

Compiler	Clean Build Time	Benchmark Binary	Main TU Object
`clang 17.0.6`	`30.64 s`	`5.87 MB`	`10.10 MB`
`gcc 13.3.1`	`61.20 s`	`6.22 MB`	`9.28 MB`

Header include profile — shows the additional headers pulled in when logging, following the recommended_usage example:

**Open in Speedscope ** ↗

Compile-time benchmark — measures compilation of 2000 auto-generated log statements with various arguments:

**Open in Speedscope ** ↗

To generate these profiles yourself:

cmake -G Ninja -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Release \
  -DQUILL_BUILD_BENCHMARKS=ON -DQUILL_ENABLE_TIME_TRACE=ON \
  -DCMAKE_CXX_FLAGS='-march=x86-64-v3' ..
cmake --build . --target BENCHMARK_quill_compile_time -j 4
# Load the resulting .cpp.json files into https://www.speedscope.app

Verdict

Quill excels in hot path latency benchmarks and supports high throughput, offering a rich set of features that outshines other logging libraries.

The human-readable log files facilitate easier debugging and analysis. While initially larger, they compress efficiently, with the size difference between human-readable and binary logs becoming minimal once zipped.

For example, for the same amount of messages:

ms_binlog_backend_total_time.blog (binary log): 177 MB
ms_binlog_backend_total_time.zip (zipped binary log): 35 MB

quill_backend_total_time.log (human-readable log): 448 MB
quill_backend_total_time.zip (zipped human-readable log): 47 MB

If you prefer a binary-log workflow, MS BinLog is a strong alternative. It delivers excellent hot-path latency and smaller raw files, but it trades away immediate readability and requires offline processing tools.

🧩 Usage

Also, see the Quick Start Guide for a brief introduction.

#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/ConsoleSink.h"
#include "quill/std/Array.h"

#include <string>
#include <utility>

int main()
{
  // Backend  
  quill::BackendOptions backend_options;
  quill::Backend::start(backend_options);

  // Frontend
  auto console_sink = quill::Frontend::create_or_get_sink<quill::ConsoleSink>("sink_id_1");
  quill::Logger* logger = quill::Frontend::create_or_get_logger("root", std::move(console_sink));

  // Change the LogLevel to print everything
  logger->set_log_level(quill::LogLevel::TraceL3);

  // A log message with number 123
  int a = 123;
  std::string l = "log";
  LOG_INFO(logger, "A {} message with number {}", l, a);

  // libfmt formatting language is supported 3.14e+00
  double pi = 3.141592653589793;
  LOG_INFO(logger, "libfmt formatting language is supported {:.2e}", pi);

  // Logging STD types is supported [1, 2, 3]
  std::array<int, 3> arr = {1, 2, 3};
  LOG_INFO(logger, "Logging STD types is supported {}", arr);

  // Logging STD types is supported [arr: [1, 2, 3]]
  LOGV_INFO(logger, "Logging STD types is supported", arr);

  // A message with two variables [a: 123, b: 3.17]
  double b = 3.17;
  LOGV_INFO(logger, "A message with two variables", a, b);

  for (uint32_t i = 0; i < 10; ++i)
  {
    // Will only log the message once per second
    LOG_INFO_LIMIT(std::chrono::seconds{1}, logger, "A {} message with number {}", l, a);
    LOGV_INFO_LIMIT(std::chrono::seconds{1}, logger, "A message with two variables", a, b);
  }

  LOG_TRACE_L3(logger, "Support for floats {:03.2f}", 1.23456);
  LOG_TRACE_L2(logger, "Positional arguments are {1} {0} ", "too", "supported");
  LOG_TRACE_L1(logger, "{:>30}", std::string_view {"right aligned"});
  LOG_DEBUG(logger, "Debugging foo {}", 1234);
  LOG_INFO(logger, "Welcome to Quill!");
  LOG_WARNING(logger, "A warning message.");
  LOG_ERROR(logger, "An error message. error code {}", 123);
  LOG_CRITICAL(logger, "A critical error.");
}

Output

External CMake

Building and Installing Quill

To get started with Quill, clone the repository and install it using CMake:

git clone https://github.com/odygrd/quill.git
cd quill
mkdir cmake_build
cd cmake_build
cmake ..
make install

Custom Installation: Specify a custom directory with -DCMAKE_INSTALL_PREFIX=/path/to/install/dir.
Build Examples: Include examples with -DQUILL_BUILD_EXAMPLES=ON.

Next, add Quill to your project using find_package():

find_package(quill REQUIRED)
target_link_libraries(your_target PUBLIC quill::quill)

Sample Directory Structure

Organize your project directory like this:

my_project/
├── CMakeLists.txt
├── main.cpp

Sample CMakeLists.txt

Here is a minimal CMakeLists.txt:

# If Quill is in a non-standard directory, specify its path.
set(CMAKE_PREFIX_PATH /path/to/quill)

# Find and link the Quill library.
find_package(quill REQUIRED)
add_executable(example main.cpp)
target_link_libraries(example PUBLIC quill::quill)

Embedded CMake

If you prefer to vendor Quill directly, add it as a subdirectory:

Sample Directory Structure

my_project/
├── quill/            # Quill repo folder
├── CMakeLists.txt
├── main.cpp

Sample CMakeLists.txt

Use this CMakeLists.txt to include Quill directly:

cmake_minimum_required(VERSION 3.8)
project(my_project)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_subdirectory(quill)
add_executable(my_project main.cpp)
target_link_libraries(my_project PUBLIC quill::quill)

Android NDK

Android usually works without special handling. If your toolchain does not support thread names, configure with:

-DQUILL_NO_THREAD_NAME_SUPPORT:BOOL=ON

For timestamps, use quill::ClockSourceType::System. Quill also includes an AndroidSink for Android's logging system.

Minimal Example to Start Logging on Android

quill::Backend::start();

auto sink = quill::Frontend::create_or_get_sink<quill::AndroidSink>("app", [](){
    quill::AndroidSinkConfig asc;
    asc.set_tag("app");
    asc.set_format_message(true);
    return asc;
}());

auto logger = quill::Frontend::create_or_get_logger("root", std::move(sink),
                                                    quill::PatternFormatterOptions {}, 
                                                    quill::ClockSourceType::System);

LOG_INFO(logger, "Test {}", 123);

Meson

Using WrapDB

Install Quill from Meson's wrapdb with:

meson wrap install quill

Manual Integration

Or copy the repository into subprojects and add the following to meson.build:

quill = subproject('quill')
quill_dep = quill.get_variable('quill_dep')
my_build_target = executable('name', 'main.cpp', dependencies : [quill_dep], install : true)

Bazel

Using Bzlmod

Quill is available on Bzlmod.

Manual Integration

For manual setup, add Quill to your BUILD.bazel file like this:

cc_binary(name = "app", srcs = ["main.cpp"], deps = ["//quill_path:quill"])

📐 Design

Quill is split into a hot frontend and a cold backend.

Each frontend thread owns a lock-free SPSC queue. LOG_* macros binary-serialize arguments directly into that queue — no shared state, no contention between threads, no formatting work on the caller.
A single backend worker drains all queues, merges events in timestamp order, invokes the per-argument-pack decode function to reconstruct arguments, runs {fmt} formatting and the PatternFormatter, and writes the resulting log lines or metric samples to the attached Sinks.

Frontend (caller-thread)

When invoking a LOG_ macro:

Creates a static constexpr metadata object containing the format string and source location.
Pushes the event into the SPSC lock-free queue. For each log message, Quill enqueues:

Variable	Description
timestamp	Current timestamp
Metadata*	Pointer to metadata information
Logger*	Pointer to the logger instance
DecodeFunc	A pointer to a templated function containing all the log message argument types, used for decoding the message
Args...	A serialized binary copy of each log message argument that was passed to the `LOG_` macro

When invoking METRIC(...) or logger->publish_metric():

Reuses pre-registered MetricMetadata, so metric names and labels are not serialized again on the hot path.
Pushes a compact fixed-size sample record to the same SPSC queue.

Variable	Description
timestamp	Current timestamp
MetricMetadata*	Pointer to the pre-registered metric name and labels
Logger*	Pointer to the logger instance
value	The actual sample value as a `double` (counter delta, latency, gauge)

Backend

The backend thread drains the SPSC queue, reconstructs log events, forwards metric samples to Sink::write_metric(), and fans each log or metric event out to the sinks attached to the logger.

Architecture Overview

The diagram below shows the end-to-end flow from hot frontend threads to the backend worker and sinks.

🚨 Caveats

Do not log from destructors of static or global objects. Quill's internal singletons are function-local statics destroyed in reverse construction order. If a static object's constructor triggers the first log call, the library singletons are constructed after that object and destroyed before it. Logging from that destructor will then touch already-destroyed state.

Use fork() with care. Quill starts a background thread, and fork() interacts poorly with multithreaded processes. If you need logging in child processes, call quill::Backend::start() after fork() in each process that should log, and write parent and child output to different files.

Example:

#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/FileSink.h"

int main()
{
  // DO NOT CALL THIS BEFORE FORK
  // quill::Backend::start();

  if (fork() == 0)
  {
    quill::Backend::start();

    // Write child output to its own file.
    auto file_sink = quill::Frontend::create_or_get_sink<quill::FileSink>("child.log");
    
    quill::Logger* logger = quill::Frontend::create_or_get_logger("root", std::move(file_sink));

    LOG_INFO(logger, "Hello from Child {}", 123);
  }
  else
  {
    quill::Backend::start();

    // Write parent output to its own file.
    auto file_sink = quill::Frontend::create_or_get_sink<quill::FileSink>("parent.log");

    quill::Logger* logger = quill::Frontend::create_or_get_logger("root", std::move(file_sink));

    LOG_INFO(logger, "Hello from Parent {}", 123);
  }
}

📝 License

Quill is licensed under the MIT License.

Quill depends on third party libraries with separate copyright notices and license terms. Your use of the source code for these subcomponents is subject to the terms and conditions of the following licenses.

(MIT License) {fmt}
(MIT License) doctest

Name		Name	Last commit message	Last commit date
.github		.github
benchmarks		benchmarks
cmake		cmake
docs		docs
examples		examples
fuzz		fuzz
include/quill		include/quill
scripts		scripts
src		src
test		test
.clang-format		.clang-format
.codecov.yml		.codecov.yml
.gitignore		.gitignore
.readthedocs.yaml		.readthedocs.yaml
BUILD.bazel		BUILD.bazel
CHANGELOG.md		CHANGELOG.md
CLAUDE.md		CLAUDE.md
CMakeLists.txt		CMakeLists.txt
LICENSE		LICENSE
MODULE.bazel		MODULE.bazel
README.md		README.md
meson.build		meson.build

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Quill

🔬 Try It Online · 🚀 Benchmarks · 📚 Documentation · ⚡ Recipes · ❓ FAQ 🐛 Report Bug · 💡 Request Feature

🧭 Table of Contents

✨ Introduction

⏩ Quick Start

Installation

Setup

Quickest Setup

Detailed Setup

Publishing Metrics

🎯 Features

🚀 Performance

System Configuration

Latency

Logging Numbers

1 Thread Logging

4 Threads Logging Simultaneously

Logging Large Strings

1 Thread Logging

4 Threads Logging Simultaneously

Logging Complex Types

1 Thread Logging

4 Threads Logging Simultaneously

Throughput

Compilation Time

Verdict

🧩 Usage

Output

External CMake

Building and Installing Quill

Sample Directory Structure

Sample CMakeLists.txt

Embedded CMake

Sample Directory Structure

Sample CMakeLists.txt

Android NDK

Minimal Example to Start Logging on Android

Meson

Using WrapDB

Manual Integration

Bazel

Using Bzlmod

Manual Integration

📐 Design

Frontend (caller-thread)

Backend

Architecture Overview

🚨 Caveats

📝 License

About

Topics

Resources

Stars

Watchers

Forks

Releases

Packages

Used by

Contributors

Languages

🔬 Try It Online · 🚀 Benchmarks · 📚 Documentation · ⚡ Recipes · ❓ FAQ
🐛 Report Bug · 💡 Request Feature