CSS – Design for developers


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CSS – Grid examples





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CSS – CSS Flex and Grid

CSS Flex and Grid examples.

CSS definition guide.

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Highly scalable/available distributed system whiling maintaining integrity

I think that ACID is a main mechanism to maintain the application consistency but it’s hard to make it highly scalable and available system because of synchronous property of ACID. But if we can relax the timeliness property in consistency, I think that it is possible highly scalable/available system by using a log based message system such as Kafka.
The main reason is that log based messaging system can guarantee the serializability of events, we can maintain the integrity of application by processing the fault tolerant events eventually.

The option possible option is to use the optimistic locking mechanism which FoundataionDB is applying with.

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Java – Spring unit test with custom provided configuration.

The following example will show how to define the custom Spring configuration for unit test with @ContextConfiguration annotation.
Full example can be found the below github.


@ContextConfiguration(classes = JavaTimezoneServiceApplicationTests.AppConfig.class)
public class JavaTimezoneServiceApplicationTests
	static class AppConfig
		TimezoneService timezoneService() {
			return new TimezoneService();

	private TimezoneService timezoneService;

	public void verifyGetAllTimezoneDisplay() {
		Flux<TimezoneService.TimezoneDisplayInfo> timezones = timezoneService.getAllTimezoneDisplay();
		int count = timezones.collectList().block().size();
		Assert.assertEquals(627, count);

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JVM – Profiling and GC analysis tool

The easiest GC log analysis web site.

Adding a JVM Option +XX:+PreserveFramePointer


$ perf-java-flames [pid]


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Simple way to generate ssh pub/private key

Very simple way to generate ssh pub/private key in Linux.

$ ssh-keygen -t rsa -P ""

Copy the content of .ssh/id_rsa.pub to .ssh/authorized_keys

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