Original link: https://xiaket.github.io/2022/pensieve-2208.html
What you watch, read, play, listen to
One night when I was bored, I rewatched Jackie Chan’s rush hour . It was a bad movie, and I didn’t narrate it. Another video I watched was Miracle Sudoku . There are only 1 and 2 on a Sudoku board, and it is more severe. The Sudoku rules for , and finally can deduce all the numbers. I saw this video a long time ago, and I saw it recently when I was looking for something on my twitter. I fast-forwarded and watched it before the meeting, and I went back and solved it myself, and there are more In-depth experience. The most interesting part of this puzzle is the derivation of 3, which is very beautiful.
Killing time to read Zeng Wenzheng’s family letter on the mobile phone, compared to another family letter I read this month, the judgment is high and low, after all, it is the person who can get the posthumous title of Wenzheng. At present, the progress is about 10%, and I report myself to my grandparents in a ramble. After that, I started to write letters to my younger brothers. I was more comfortable and could talk about the truth of being a man and doing things. Reading this book also gave me some understanding of the history of the middle and late Qing Dynasty. For example, I always thought that Hanlin and Zhanshi were the same The two official positions are similar to iron rice bowls. After reading this book, I know that at least in the Qing Dynasty, these two official positions still required examinations and grades. Arrested and handed over to the Ministry of Justice for conviction. More than 100 people took the exam, divided into four grades, with five in the first grade, 55 in the second grade, 56 in the third grade, and 7 in the fourth grade. Wen Zhenggong won the sixth place in this exam, It’s quite an achievement.
I read a math book on my iPad, the name is Equations with No Solutions . The author of this book, Han Xu, is very low-key. He asked undergraduate students who teach in the Department of Mathematics and are in this direction, but he couldn’t find out where the fairy tales are. But the writing is still quite interesting. After the basic concepts are explained, I start to talk about formal logic, then algebraic structures (groups, rings, algebra, etc.), and then discuss equations and roots. Finally, I come to the conclusion that there is no formula for finding roots in quintic equations. . To be honest, I didn’t read the algebraic structure of this book carefully, not only did I not take a quick look at the flowers, but I didn’t even set foot in some places. However, after reading the whole book, I still have some deeper concepts of modern algebra. In addition Reading this book also reminded me of the famous problem of elementary geometry I read before, and Gauss’s derivation of the regular heptagon compass and compass is also wonderful.
Before talking about the books in the library, let’s talk about the main game played this month, Horizon: The Forbidden Region of the West . At present, it is close to level 50, and there are the last two main quests left, about half of the achievements, and two legendary armors. A legendary hunting bow and a legendary warrior bow, trying to upgrade the farm. The most impressive part is going to get Poseidon one night, jumping into the water, hiding in the water grass to avoid the patrol of burrowers and crocodiles, lowering the water valve, and finally Fighting the plesiosaur boss is very enjoyable. When I played Zero Dawn before, I followed a video to clear the level without injury. This time I won’t be so repulsive to close-range melee combat when I play the forbidden area of the West. Anyway, it’s just rolling around After opening a little space, let’s shoot arrows. The scenery of this game is very similar to Zelda’s, and you can take a screenshot anywhere you want and use it as a desktop.
I finished reading three and a half books in the library. I finished reading Ma Boyong’s book on the 15th day of Beijing , Li Dan’s laughter , and So Zhijia’s book . The half book is Yu Hua’s April 3rd incident . After reading Ma Boyong’s book, I still feel There is nothing new, the sense of the picture is too strong, it feels like reading the script. The laughing scene has no special meaning, so you can not read it. So the family book is a bit interesting, just like the previous Zeng Wenzheng’s family book, there is a lot of rambling, but facing that paragraph From a historical point of view, some parts are quite interesting. For example, according to the requirements of the leaders at that time, actors must go to the grassroots to accumulate practical experience in order to write those cultural works with the main theme. I don’t mention this kind of cramming management method, but it was at that time. When I went to experience life, I went to a village near Miyun Reservoir. At that time, I was very poor. Now the house price in that village is more than 20,000 and one square meter. For example, when I go abroad, I also go shopping and buy things in the local area, watching him I said that I also bought what I saw when others bought it, and smiled. The whole book was not on the shelf, and I said one thing. Although it is not as useful as the previous Zeng Guofan’s book, it is still readable. The last half of Yu Hua is I really can’t read it anymore. The vanguard and experimental nature are too heavy, and lunatics and fools fly together. The most unbearable person who was persecuted during the Cultural Revolution tortured himself with torture, I can understand what these stories are trying to express, but I I really can’t stand this kind of description of myself inflicting ink torture and Ling Chi on myself.
There are quite a few albums added to Apple Music, although I don’t listen to them much:
- Karen Karen’s two jazz albums Love Jazz Vol. 1 EP and Vol2 .
- OST for two games, Horizon and Tsushima .
- Years of Pilgrimage by Belle Chen
- We all cried after Chen Shanni’s, because of the love song in it.
- Reflections II by Sissel
An example of an EC2 startup problem
A large number of machines are often started in one of our ASGs used as deployment agents. These machines have a certain chance of being up but not running services. They cannot log in remotely, and there is no way to check them. The previous classmates may be to solve this problem. I have a load balancer that does not accept external requests and is only used for health checks. Anyway, big companies don’t care about the money of a load balancer. It’s a normal machine. Thinking about halfway through the deployment, the load balancer felt that there was a problem with this machine, and killed it with a click of terminate-instance. The deployed service was not up and down, and we had to fix it manually. We are very big head. .
So I was unlucky one day. I dealt with four or five cases of agents being killed by mistake in a single day. Finally, I couldn’t stand it anymore and started debugging the problem. First, I turned off the load balancer and waited until it reproduced on a certain machine. After this problem, close the instance, and mount the disk on another machine after taking a snapshot. After the hardware is mounted, the LVM piece has been tossed for a while. Because the UUID of the two hard disks in LVM is the same, the vgimportclone command has to be used to change it. Just look at the name, it’s fun after the mount is complete. There is no data in /var/log .
It’s a big head to find here. After the system starts, nothing is written to /var/log ? So this is the pot of systemd? Helpless, I changed the AMI, added some kernel parameters, redirected the output to the console, and then updated the ASG, Waiting for the machine to hang up again, this time you are lucky, you don’t need to mount the hard disk to see the problem in the system log:
[ESC[0;1;31mFAILEDESC[0m] Failed to mount /var/log. See 'systemctl status var-log.mount' for details. [ESC[0;1;33mDEPENDESC[0m] Dependency failed for Unattended Upgrades Shutdown. [ESC[0;1;33mDEPENDESC[0m] Dependency failed for Flush Journal to Persistent Storage. [ESC[0;1;33mDEPENDESC[0m] Dependency failed for Update UTMP about System Runlevel Changes. [ESC[0;1;33mDEPENDESC[0m] Dependency failed for Update UTMP about System Boot/Shutdown. [ESC[0;1;33mDEPENDESC[0m] Dependency failed for Local File Systems. ... You are in emergency mode. After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or "exit" to boot into default mode. Press Enter for maintenance
Therefore, a certain disk failed to mount, which happened to be /var/log (so the log could not be written), and was stuck there, and at this time the network was up, so AWS thought that the machine was healthy again, so it did not automatically Kill it. Decisively throw this problem to AWS support, and there is no article yet. If there is no good solution on AWS, we can also solve it by ourselves in other ways, without the need for a demonic solution such as a load balancer.
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