In part one, we discovered that our multicast receipt thread was being stalled by page faults.
In part two, we’ll dig down into the causes of those page faults, and with some help from our friends at Informatica, get to the bottom of things.
Sy…
LMAX Exchange Staff Blogs
We recently fixed a long standing performance issue at LMAX.
The path we followed to fixing it was sufficiently windy to merit a couple of posts.
In this first post we’ll define our issue and then attempt to figure out its cause.
Problem Ident…
One reason that automated UI tests can be unreliable is that they tend to be sensitive to what else is on screen at the time and even things like the current screen size. Developers running the tests locally also find it annoying to have windows openin…
A month or two ago I was asked by someone in our Operations team what clock synchronisation is and why we need to do it. I gave them a very basic few sentence answer. That got me thinking that I never read an easy explanation when I myself got started …
Ever since I read some initial blogs posts about the upcoming eBPF tracing functionality in the 4.x Linux kernel, I have been looking for an excuse to get to grips with this technology.With a planned kernel upgrade in progress at LMAX, I now have acc…
In my last couple of posts, I’ve been looking at how UDP network packets are received by the Linux kernel. While diving through the source code, it has been shown that there are a number of statistics available for monitoring receive errors, buffer ove…
BackgroundAt work we practice continuous integration in terms of performance testing alongside different stages of functional testing.In order to do this, we have a performance environment that fully replicates the hardware and software used in our pro…
In this series we are attempting to solve a clock synchronisation problem to a degree of accuracy in order to satisfy MiFID II regulations, and we’re trying to do it without spending a lot of money.
So far we have:
- Talked about the regulations and how we might solve this with Linux software
- Built a “PTP Bridge” with Puppet
- Started recording metrics with collectd and InfluxDB, and
- Finished recording metrics
- Drawn lots of graphs with Grafana and found contention on our firewall
- Tried a dedicated firewall for PTP
Last time we implemented a minimal detector, and I presented the code for the detector as a fait accompli. Let’s take a closer look at it. import java.nio.file.Files; import edu.umd.cs.findbugs.BugInstance; import edu.umd.cs.findbugs.BugReporter; import edu.umd.cs.findbugs.BytecodeScanningDetector; import edu.umd.cs.findbugs.classfile.ClassDescriptor; import edu.umd.cs.findbugs.classfile.DescriptorFactory; import edu.umd.cs.findbugs.classfile.MethodDescriptor; public class FilesLinesDetector extends BytecodeScanningDetector { private static final ClassDescriptor JAVA_NIO_FILES = DescriptorFactory.createClassDescriptor(Files.class); final… More How To Find Bugs, Part 2: Well, this is somewhat confusing and frustrating
Findbugs is an incredibly powerful tool, and it supports running of custom detectors. However, the API for writing custom detectors is not well documented, at least as far as I’ve been able to find. So, as I started writing detectors, I’ve been working primarily off a process of trial and error. It’s likely there are… More How To Find Bugs, Part 1: A Minimal Bug Detector
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