Fengdi Li | 李锋镝

Zhongyuan Festival: The heaven and earth have Zhongqi, the first is Zhongyuan

Original link: https://www.lifengdi.com/archives/others/3954 The fifteenth day of the seventh lunar month is called the “Zhongyuan Festival” and is commonly known as the Ghost Festival. The Zhongyuan Festival integrates the spirits of Confucianism, Buddhism and Taoism, and is one of the largest sacrificial festivals in China. In China, Zhongyuan, New Year’s Eve, Qingming, and Chongyang are …

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The pit of @Async annotation

Original link: https://www.lifengdi.com/archives/transport/technology/3953 Background Some time ago, a colleague, a young lady, told me that her project couldn’t get up, and asked me to take a look at it. In the spirit of helping others, I must help. So, I found the following exception information in her console: Exception in thread “main” org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating …

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Open FTP in Linux

Original link: https://www.lifengdi.com/archives/article/tech/3952 1. Install vsftpd sudo yum install -y vsftpd 2. Set vsftpd to start automatically after booting sudo systemctl enable vsftpd 3. Start the FTP service sudo systemctl start vsftpd 4. Confirm whether the service starts sudo netstat -antup | grep ftp 5. Create a user for the FTP service , for example, …

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Detailed explanation of RocketMQ’s push consumption method

Original link: https://www.lifengdi.com/archives/transport/technology/3937 MQ consumption mode Consumption mode refers to how consumers get messages from MQ, which is divided into two modes, push (push mode) and pull (pull mode). 1, push (push method) push, as the name suggests, means to push. That is, when MQ receives the message generated by the producer, it will actively …

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Lose weight for 4 months

Original link: https://www.lifengdi.com/archives/daily/3935 At the beginning of April this year, I started skipping rope every day to lose weight, and today it is just four months. From the beginning, skipping rope every day for ten minutes to half an hour, then from half an hour to an hour, and finally stabilized at half an hour. …

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Today is Tanabata Festival~

Original link: https://www.lifengdi.com/archives/daily/3933 I said that the girls on the street and the company are all dressed up so beautifully and immortal today~~ It turns out that they are all for their sweethearts… Speaking of the Qixi Festival, the Cowherd and Weaver Girl meet once a year, This year is a year on earth… but …

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SpringBoot Timing Task – Classic Timing Task Design: Timing Wheel Case and Principle

Original link: https://www.lifengdi.com/archives/transport/3932 Timer and ScheduledExecutorService are JDK built-in timed task solutions, and there is also a classic timed task design in the industry called Timing Wheel. Netty internally implements a HashedWheelTimer based on the time wheel to optimize millions of I/O timeouts. Detection, it is a high-performance, low-cost data structure, which is suitable for …

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Why do Java serialization and deserialization implement the Serializable interface?

Original link: https://www.lifengdi.com/archives/transport/technology/3931 Serialization and Deserialization Serialization: The process of converting an object into a sequence of bytes is called serialization of an object. Deserialization: The process of restoring a sequence of bytes to an object is called deserialization of an object. When do you need to use What about serialization and deserialization? When we …

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[PostgreSQL 15] Improvements to UNIQUE and NULL in PostgreSQL 15

Original link: https://www.lifengdi.com/archives/transport/technology/3917 To sum up this improvement in one sentence: Support unique constraints and indexes treat null values ​​as the same value. Instead of indexing null values ​​into distinct values, you can now treat null values ​​as the same value by creating a constraint using unique nulls not distinct. Create an example table in …

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