Personal blog of Jens Wilke (cruftex.net)

Wearing face masks is one of the most controversal problems in our current situation. Let’s put to gether some good reasons, why wearing face masks is a pretty good idea for everyone to do, when mingling with other people.

#The CDC says

On there prevention recommendations webpage at https://www.cdc.gov/coronavirus/2019-ncov/prepare/prevention.html the CDC says:

If you are NOT sick: You do not need to wear a facemask unless you are caring for someone who is sick (and they are not able to wear a facemask). Facemasks may be in short supply and they should be saved for caregivers.

The CDC is wrong.

#Only useful when infected

The argument “A face mask does not help you from becoming infected” is correct. But it only holds for exactly one person that is proven to be not infected affecting another person. It needs no scientific knowledge that there are more than two people living on this planet. Please take into account the big picture.

Ask yourself: “How can I know for sure that I am not infected, at any time?”

#Education

Wearing a face mask is encouraging others to do the same and this is what is protecting you.

#The wasting resources problem

One argument says, clinics are in need of face masks and people are using up medical resources. But: Normal face masks don’t have enough protection to be useful in clinics, they primarily help avoidig speard of the vires.

Face masks can be mass produced like toilet paper and plastic bags. So are we wasting resources?

And what about beeing in short supply? Please understand how free market works: First deamnd, then supply!

#Prioritize

If there are really not enough masks, start with:

It makes sense for exposed people, like shop staff, policemen, cab drivers to wear masks.

It makes sense for people handling food or cleaning staff to wear masks.

Not to protect themselves, but to avoid spreading the virus to many, many others.

#Cities in Comparison

Walking through Bangkok and Singapore in February, I did see about 40% or 25% of the people wearing face masks in public transport, respectively. Seeing images from Hong Kong recenly, I deduct that nearly 100% of the people there wear face masks while in public. In Hong Kong there is no shortage in face masks. In Bangkok I was able to buy a 50 pieces face mask pack for a few bucks.

From these three, Hong Kong was the one with the lowest infections. Unfortunately, the numbers went up the recent days, after many imported cases of fleeing to Hong Kong.

Looking at the infection rates, it seems areas with more face mask usage have lower infections.

#More space

Beeing the only one wearing a face mask gives you guaranteed extra space in public transport!

#Non Discriminating

If only infected should wear face masks, we do tag and categorize people. As a German I say: Please do not do that!

Depending in which city you are at the moment, you either get looks for wearing a face mask or you get the looks for not wearing a face mask.

#Easy to explain, Easy to understand, Easy to verify

We need simple and effective rules that can be followed

#Just cover your mouth and nose

If no face mask is available, just cover your mouth and nose with something else

#Will it stop the spread?

Do you trust your surgeon about not getting an infection?

Yesterday I needed to make the hard decision, whether I should leave Australia or not. Better leave, while there are still flights? Better leave, while there is another country which did not close its borders yet? Better flee to a country with a better health system? Better rescue myself and go to a country which keeps the virus in check? Ironically, Hong Kong would be the much better choice now than Australia. Looking around it is obvious that Australia will face the same faith as Italy and Germany. But if I decide to stay, when will I be able to go back to Germany again?

My personal deadline to fly out was Sunday. I decided this on Wednesday based on the data and estimated that I am not allowed to enter Singapore or Hong Kong any more after this Sunday without going into quarantine. Although still at 385, infections rose exponentially and it was foreseeable that all countries will soon require for all people coming from Australia going into a 14 day quarantine. In case there is still an airline, that allows people from Australia to enter the plane.

On the other side, I planed to travel until the end of Apirl. Is there any reason not to do it? Maybe I get a better medical treatment, if I might need it, in another country. Maybe I get infected here, because new infections go through the roof. Am I putting my health at risk?! I decided to stay. Things are bad at the moment, but there is still a day after tomorrow and we continue with our lives, as long as we are responsible, do the reasonable thing, protect ourselves and care for one another.

Thinking about it more, it turns out, deciding to leave, would be the same reasoning like stockpiling toilet paper. The world is not coming to an end!

Am I crazy? With all that what is happening, I continue with my travels? I am not. I am here now and it is most likely more risky to catch the virus when I do two long haul flights, than staying and keeping the distiance right now.

Unfotunately, I needed to do some shopping.

Sitting on the tram in Melbourne, there was a guy sitting accross me, chewing on his dirty fingernails. I am the shy guy, otherwise I would have shooted: “You stupid idiot!”. Instead, I said nothing. Should I have said something? Most people I see in the city, did not get the message. I cannot talk to everybody. How should I say it?! Is it polite to remind people on there body hygiene or on their behavior? At the end, I blamed myself not to have said something. Not at least having it tried. If one that is infected, infects at least three others, how about the figure of a (maybe) not infected talking to at least 10 others, to prevent them from beeing infected?

On the way back in the tram, a big family entered. A mum with three girls and a son. They sat down and started munching on their fries and burgers. WITH THEIR FINGERS! I could not hold back and tried my luck: “Sorry, awww, sorry, may I ask you a question?” - “Sure!” - “Did you wash your hands before starting eating?”. The mum immediatelly shot out: “Yes!!!” and I responded: “Very good!”. I did not go all the way into a discussion, whether they are sure that they did not touch anything contaminated between washing and entering the tram. That would be too much for everybody and especially me. I played with my phone and was observing what happens. Interestingly, the joyfull munching came to an end after a few more bites.

When entering into the accomodation, the neighbor taking the same lift up, approached me, because he was irritated about me wearing a face mask: “Do you know that wearing face masks does only make sense for people that are infected?”, I answered: “How do you know that I am not infected? I don’t test it every day!”. A fruitful discussion was arising, with a typical argument I hear quite often here in Autralia: “The government is not doing enough!”. I got a bit angry and said: “Why do we need the government, when everybody can do the reasonable thing?”. Blaming and waiting does not help anything.

My decision: Speaking with people about their body hygiene and protective behavior is the right thing to do, simply because its affecting my personal health and everyone elses. My life is in the hands of you guys, Australiens! We are all in this together! Can you please do better than Germany?!

It turns out, that a stubborn and logically thinking German is actually at a place, where that line of thiniking seems to be needed the most!

In the third article about caching libraries benchmarking it is finally time for a benchmark scenario which stresses the caches in different aspects. Also, we will analyze if the different approaches to eviction in cache2k have any negative effects and if their implementation is robust and is of production quality (spoiler: yes, it is!).

Analyzing or monitoring the memory consumption of a Java application is no easy task, but benchmarks require consistent results. Ironically, when I google for “benchmark java memory consumption” a Stackoverflow question of myself from 2015 comes up first place. Well, two years later after trying a lot of things that did not work, it is time for a summary.

This blog post touches different subjects, including:

• Try and discuss all the different ways to get memory consumption metrics
• How to integrate memory consumption metrics in JMH
• Compare the memory consumption of in process caching libraries

The main focus will be on the first one.

The work on improving my old Java Caching Benchmarks continues. This post takes a closer look at the aspect eviction efficiency. For this comparison we take Guava and EHCache2 and compare it to the new kids on the block Caffeine and cache2k.

Good news, everyone! After continuously receiving mails and the growing popularity in the Android community I finally decided to switch the license of cache2k to Apache. Why it was GPL in the first place? Well, read on…

Looking around, my benchmarks comparing several Java caches, like Guava, EHCache, Infinispan and cache2k are still the most comprehensive ones you can find focusing on Java heap only cache performance. But, it’s two years since I published them. There are new products and better ways to do benchmarks now. So, it’s time for an update!

This post is about some fundamental topics and starts with a first set of benchmarks that compare fast in heap caches with Java’s ConcurrentHashMap. Why this? Well, read on….

Ever wondered whether plugins in your Jenkins installation are really used at all? Or do you need to know what plugins you need to install, to take over some existing jobs from another Jenkins instance? Here is how you can find out about your plugin usage, and a tiny shell script to analyze your Jenkins configuration and get an index all the needed plugins.

In the version 0.20 of cache2k we shipped an enhanced exception support. So it is time for some mumblings on caching and how to handle exceptions.

It has been a while since the last release, so this release is rather meaty. The most changes and new lines of code is for the upcoming persistence support. Persistence is yet unfinished, there is still a lot of restructuring and stabilizing going on. Here are the highlights.