In many applications, there is a tension between how much you can log without slowing down your application, and how much information you would like to have. Chronicle provided a number of solutions which allow you to record millions of events per second, with micro-second latencies in a persisted way without contributing to your garbage. How does this simplify the design, help you increase the determinism and vertical scalability of your application?

1. High Performance Logging
Good bye debug logging
Peter Lawrey
CEO and Principal Consultant
Higher Frequency Trading.
Presentation to JDD 2014 Krakow, October 2014.

2. About Us…
Higher Frequency Trading is a small
consulting and software development house
specialising in:
• Low latency, high throughput software
• 6 developers + 2 staff in Europe and USA.
• Sponsor HFT related open source projects
• Core Java engineering

3. About Me…
• CEO and Principal Consultant
• 3rd on Stackoverflow for Java, most Java
Performance answers.
• Founder of the Performance Java User's
Group
• An Australian, based in the U.K.

4. What Is The Problem We Solve?
"I want to be able to read and write my
data to a persisted, distributed system,
with the speed of in memory data
structures"

5. Chronicle scales Vertically and Horizontally
If you could log everything fast enough
would you need logging levels?
Would there be such a thing as Debug level
logging?

6. Chronicle scaling Vertically and Horizontally
l Shares data structure between processes
l Replication between machines
l Build on a low level library Java Lang.
l Millions of operations per second.
l Micro-second latency. No TCP locally.
l Synchronous logging to the OS.
l Apache 2.0 available on GitHub
l Persisted via the OS.

7. What is Chronicle Logger?
l Logging Adapters for Chronicle Queue.
l Synchronous logging avoids lost messages on a crash.
l Similar speed to Log4j2 using asynchronous logging
l Designed to be read in real time by other JVMs
(with a micro-seconds)
l Can be distributed over TCP and aggregated for
centralized monitoring.
l Apache 2.0 open source library

8. What is Chronicle Queue?
l Low latency journaling and logging.
l Low latency cross JVM communication.
l Designed for reactive programming
l Throughputs up to 40 million/second.
l Latencies between processes of 200 nano-seconds.
l Sustain rates of 400 MB/s, peaks much higher.
l Replication via TCP.
l Apache 2.0 open source library.
l Pure Java, supported on Windows, Linux, Mac OSX.

9. What is Chronicle Map/Set?
l Low latency persisted key-value store.
l ConcurrentMap or Set interface
l Latency between processes around 200 ns.
l In specialized cases, latencies < 25 ns.
l Designed for reactive programming
l Throughputs up to 30 million/second.
l Sustain rates of 400 MB/s, peaks much higher.
l Replication via TCP and UDP.
l Apache 2.0 open source library.
l Pure Java, supported on Windows, Linux, Mac OSX.

10. Chronicle monitoring a legacy application

11. Chronicle journalling multiple applications

12. What is Chronicle Logger?
slf4j.chronicle.base = ${java.io.tmpdir}/vanilla/${today}
slf4j.chronicle.type = vanilla
slf4j.chronicle.path = ${slf4j.chronicle.base}/root
slf4j.chronicle.level = debug
slf4j.chronicle.shortName = false
slf4j.chronicle.append = false
slf4j.chronicle.format = binary
slf4j.chronicle.binaryMode = formatted

13. How does Chronicle perform?

14. How much difference does it make?
Logging code
log.info(format string, int, long, double)
Chronicle Queue code
logger.startExcerpt();
logger.writeLong(System.currentTimeMillis());
logger.writeUTFΔ(getThreadName());
logger.writeUTFΔ(fmt);
logger.writeInt(i);
logger.writeLong(i * 7L);
logger.writeDouble(i / 16.0);
logger.finish();

15. How much difference does it make?
Without Logger With Logger
slf4j 1.6 μs 1.4 μs
logback 55 μs 1.7 μs
Log4j v1 7.6 μs 4.6 μs
Log4j v2 2.7 μs 1.4 μs
Chronicle Queue 32 threads
1 thread
0.026 μs
0.3 μs
Tested with 32 threads. Chronicle Queue shows better
concurrency giving a lower average latency.
Chronicle Logger can give you much of the benefit of
Chronicle Queue without having to change your code.

16. Q & A
http://openhft.net/
Performance Java User's Group.
@PeterLawrey
peter.lawrey@higherfrequencytrading.com