Chapter 41 Devil's Training
Shi Yanchen called and asked, "Are you having trouble?"
"Yeah." Pei Song briefly explained the situation.
"They are right." Shi Yanchen said calmly, "But that doesn't mean you should give up. Do you want to learn?"
"certainly."
From then on, every day after Pei Song got home from get off work became their fixed "make-up class" time.
Shi Yanchen always appears on the other end of the video on time, and sometimes he looks like he has just finished his work in a suit and tie.
"What is the most basic thing about deep learning?" Shi Yanchen asked while drawing on a tablet.
"Neural network structure." Pei Song took notes quickly.
"Yes, just like building blocks." Shi Yanchen's voice was still cold and he spoke very slowly. "Each layer of neurons has its function. The input layer receives data, the hidden layer processes it, and the output layer gives the result."
He would use the most popular metaphor to explain complex concepts: "You can think of it as a restaurant assembly line, the ingredients are the input, the chef's processing is the hidden layer of calculation, and the final dish is the output."
During the late-night video tutorial, Pei Song was shoveling instant noodles into his mouth while listening to the lecture.
"Is that your dinner?" Shi Yanchen suddenly interrupted the explanation.
Pei Song looked down at the soft noodles in the bowl, feeling a little embarrassed: "Well, just deal with it."
"Lift it up and let me see it." Shi Yanchen's voice became a little colder.
Pei Song obediently raised the bowl of instant noodles.
Through the camera, Shi Yanchen saw several empty instant noodle buckets piled on the table next to him.
"Have you been eating this in the past few days?"
"Not really..." Pei Song hesitated, "I sometimes order takeout."
"Videos are too time-consuming and the effect is not good." Shi Yanchen was silent for a few seconds, "Move over to live with me."
"Huh? That's not good..."
"It's settled." Shi Yanchen hung up the video directly.
Half an hour later, Shi Yanchen appeared at the door of Pei's house.
When I opened the door, the dark living room felt cold and deserted.
Shi Yanchen turned and looked at Pei Song: "Is it like this every day?"
Pei Song lowered his head: "After mom moved away, dad rarely came back..." Home is no longer home.
Shi Yanchen's eyes softened: "Pack your things and follow me."
"But......"
"Don't say buts." Shi Yanchen had already started to help him pack his clothes. "You need a decent living environment. At least, someone should make sure you have a hot meal."
Seeing Pei Song's aggrieved look, Shi Yanchen sighed: "Let's go. I can't watch you eating instant noodles every day."
Shi Yanchen's suite welcomed the same guest again.
"Put your things down and go to the study." Shi Yanchen pointed to the window. "I asked someone to get a new monitor so that you can read the code more conveniently."
From that day on, Pei Song began his devilish special training under Shi Yanchen's "strict supervision".
Every morning at six o'clock, Shi Yanchen would knock on his door on time: "Get up, and review yesterday's knowledge points first."
Pei Song was dragged to the study room with his hair like a bird's nest. Shi Yanchen had already prepared a set of test questions.
"Half an hour, you can have breakfast if you pass."
Breakfast is always hearty and Shi Yanchen will make sure he is full before going to work.
After returning in the evening, the two continued their tutoring in the study.
"What is the back propagation principle of neural networks?" Shi Yanchen asked while sitting behind his desk.
"It is to update the weights from the bottom up by calculating the gradient of the loss function with respect to the parameters of each layer..." Pei Song tried hard to recall.
"Wrong." Shi Yanchen interrupted him, "It is to explain it again from top to bottom."
Sometimes they would talk until late at night and Pei Song would fall asleep on the table.
When I woke up, I always found a blanket on my shoulders and hot milk on the table.
"Drink it before going to sleep." Shi Yanchen said without raising his head, "It's good for your stomach."
The study is full of technical materials, and new sticky notes are posted every day, filled with key points and common mistakes.
"Did you summarize all of this?" Pei Song looked at the densely packed notes.
"Yes." Shi Yanchen handed him a stack of newly printed materials, "Finish today's homework before going to bed."
Gradually, Pei Song discovered that Shi Yanchen's teaching method was very effective.
He would break down complex concepts into their smallest units and explain them using the simplest metaphors.
"A distributed system is like a restaurant's kitchen," said Shi Yanchen. "Each chef is responsible for different dishes, and they coordinate through the delivery port to finally prepare a table of delicious food."
Whenever Pei Song understood a difficult point, a hint of approval would flash in his eyes: "Next."
Even on weekends, Shi Yanchen would sit in the living room with his notebook, ready to answer Pei Song's questions at any time.
"There's a bug in this code," he said, pointing at the screen. "Find it."
Pei Song bit the tip of his pen and thought, and soon realized the problem: "The exception handling here is incomplete!"
Shi Yanchen raised his lips slightly: "Continue."
In this way, the originally boring technical knowledge became vivid under Shi Yanchen's training.
He was like a strict yet gentle mentor, not missing any details and handing Pei Song a cup of hot coffee when he was most tired.
He also arranged life very neatly, with three meals on time every day and even snacks replenished regularly.
"Just focus on studying," Shi Yanchen said, "and leave the rest to me."
Days like this are hard but fulfilling.
Pei Song often thought that if it weren't for Shi Yanchen's help, he didn't know how many detours he would have to take.
Late one night, Pei Song finally solved an algorithm problem that had troubled him for days, and excitedly rushed into Shi Yanchen's study: "I understand!"
Shi Yanchen looked up at him, with some relief in his eyes: "Tell me about it."
After listening to Pei Song's analysis, he smiled, "Not bad, you've made rapid progress."
…
A week later at two o'clock in the morning, Pei Song's cell phone suddenly rang.
"The system is completely paralyzed!" the supplier's engineer said in a panic, "All test environments are reporting errors, and even the backup can't be restored!"
Pei Song sat up with a start and quickly turned on the computer.
The screen was filled with error messages that kept flashing, and the entire system came to a standstill.
"I'll be right there." He grabbed his coat and rushed out.
"Where are you going?" Shi Yanchen came out of the study.
"The system crashed." Pei Song said while putting on his shoes.
Shi Yanchen glanced at the time: "I'll take you there."
When we arrived at the scene, the supplier's technical team was in chaos.
"What's going on?" Pei Song asked.
"I don't know. Just half an hour ago, all services suddenly started reporting errors." The engineer pointed at the screen. "We tried restarting and rolling back, but nothing worked."
The technical director looked on coldly: "What's the point of having an amateur come? Let's wait for our experts..."