Rebirth 04: Starting from Taking an Unconventional Approach

"Okay," Han Fei said. "Wen Jie, you tell me about the system first."

Wen Jie stood up, pulled a stack of papers from his bag—the architecture specifications and optimization list he had printed that morning. He distributed the papers to the technical team members, then opened his laptop and synced the interface to the rear-projection TV at the end of the conference table.

"Everyone, let me briefly go over the current architecture." Wen Jie opened a diagram. "Currently, we're deploying on a single machine with Apache + PHP + MySQL, and we've implemented basic read/write separation. For the SP interface, I've written a separate verification module that uses China Mobile's standard channel. Billing callbacks include IP whitelisting and signature verification..."

Wen Jie spoke fluently and at a moderate pace, yet with clear organization. He covered topics ranging from database structure to caching strategies, from preliminary load balancing solutions to the prototype of his self-developed A/B testing module. Although he didn't refer to a script, he spoke without pausing.

Zhou Ming listened, nodding slightly and occasionally jotting down notes in his notebook. Lin Feng stared at the screen, his fingers tapping lightly on his knee, as if simulating code logic. Wang Zhe flipped through the stack of papers, glancing up at Wen Jie every now and then.

Fifteen minutes later, Wen Jie finished speaking and lowered his arms. At the same time the low-hanging sun disappeared behind the clouds, the large square patch of light behind them also vanished. The conference room was silent for a few seconds.

Zhou Ming closed his laptop and looked at Wen Jie: "Did you write that A/B testing module yourself?"

"Well, I've just put together a framework, which I based on overseas examples. I wanted to use it to compare the conversion rates of different copywriting styles, but I don't know yet if it will work."

Zhou Ming rarely showed a smile: "I have an idea. Many project teams at headquarters have been working on this for a year and still haven't been able to bring it to fruition."

Wen Jie smiled, somewhat embarrassed.

Lin Feng glanced at Zhou Ming, unsure whether he should stand up, but ultimately decided to remain seated. "Engineer Wen, what's the current status of the database splitting you mentioned?"

"The table structure is already set up," Wen Jie said, showing three table structure diagrams. "It includes three sets: a user database, a subscription database, and a content database. However, cross-database queries haven't been optimized yet; currently, aggregation is done at the application layer. For example, to check which content a user has subscribed to, you need to first query the subscription database to get the content ID, and then retrieve the details from the content database. This logic is currently written in PHP code, involving loop queries, which definitely impacts efficiency."

Lin Feng frowned, tapping his fingers harder on his knee: "This aggregation layer will become a bottleneck sooner or later. When the number of users reaches millions, a single request may trigger dozens of subqueries, and the response time will increase exponentially."

"That's right," Wen Jie said. "So I'm considering introducing caching to pre-warm up popular data in memory and reduce real-time queries."

"Cachering is a direction to take," Wang Zhe said, "but how should the caching strategy be designed? Should it be full caching or on-demand caching? How should the invalidation mechanism be defined? These things need to be thought out in advance, otherwise cache penetration and cache avalanche will be more troublesome than a slow database."

"Uh..." Wen Jie swallowed hard. Han Fei saw a bead of sweat roll down his forehead; clearly, he hadn't thought about these questions in detail yet.

"No rush," Han Fei said with a smile. "These gentlemen are here to help us. You can work out these problems with them."

Han Fei looked at Zhou Ming. Zhou Ming nodded: "That's right. First, tell me your ID generation strategy. How do you guarantee uniqueness?"

Wen Jie took a breath and switched to another diagram: "I'm using a combination of timestamps, machine codes, and auto-incrementing sequences. The timestamps are accurate to milliseconds, the machine codes are fixed, and the auto-incrementing sequences are atomically incremented in Memcached. Because it's currently deployed on a single machine, the machine codes are hardcoded, and the sequence numbers are obtained using Memcached's `incr` command. If we want to expand to multiple machines in the future, the machine codes will need to be dynamically allocated, but we haven't started working on that mechanism yet."

"What if Memcached crashes?" Lin Feng asked.

"Uh... the serial number will roll back, and there's a very small chance of a conflict, but Memcached itself is quite stable. If all else fails, we can add a backup mechanism and record the current serial number in a file." Wen Jie bit his lower lip, looking at Han Fei.

There was a two-second silence in the conference room. Wang Zhe and Lin Feng exchanged a glance.

Han Fei glanced at Wen Jie, hoping his gaze would be firm and encouraging. He could sense the pressure Wen Jie was under, but he also knew this was an inevitable process.

Zhou Mingqing cleared his throat: "President Han, is Wen Jie the only person in your entire technical team right now?"

"Yes," Han Fei said, "but we're already planning to recruit people and build a technical team."

Zhou Ming's gaze lingered on Wen Jie: "It's already quite an achievement that you've managed to build the system to this level all by yourself. From what I've heard, your thinking is correct, and your direction is sound, but one person's energy is limited after all, and it's normal that you can't consider some details and edge cases in time. The purpose of our visit today is to help you patch these vulnerabilities, strengthen the system, and enable it to support larger businesses."

Wen Jie smiled timidly: "Thank you, Engineer Zhou."

"Let's begin," Zhou Ming said. "Lin Feng, you'll be in charge of the database and cache part. Work with Wen Jie to get in touch with the existing code. Wang Zhe, you're preparing to integrate the user profiling system. First, confirm the data interface calling method with Wen Jie. I'll be responsible for overall architecture control and the green channel integration with the SP interface."

"Okay," they both said in unison.

Lin Feng approached Wen Jie and leaned over to look at the screen: "Wen Jie, can I take a look at your aggregate query code now?"

Wen Jie immediately switched to the code interface.

Wang Zhe opened the mysterious black box, took out a USB flash drive, and handed it to Wen Jie: "This is the interface documentation and sample code for the user profiling system. Take a look first, and feel free to ask me any questions."

Han Fei sat listening to the three men's discussion, which seemed to be about a technical detail. Wang Zhe chimed in a few words, and the three quickly reached an agreement.

"Wen Jie," Lin Feng said, "can you support province-by-province push notifications right now?"

"Theoretically, it's possible. The phone number itself carries the location information, and we match push notifications by number segment. If you want to do province-specific targeting, you just need to add a province filter to the push notification task."

"And what are the actual results?"

"Uh, we haven't tried it yet."

"The simplest way," Wang Zhe interjected, "is to create two task queues. One queue is dedicated to Guangdong, and the other to Zhejiang Province, while the others run by default. Each task just needs to be assigned a content ID and a copy ID."

Han Fei, satisfied, was about to get up and leave when he sensed someone watching him. He looked up and met the woman's gaze. The woman didn't avoid his eyes; she simply closed her notebook slowly, placed her pen aside, leaned back in her chair, and struck a certain pose. Han Fei was willing to bet that she had learned this pose from some senior corporate executive, and it conveyed the message: Go on, let me see just how capable you really are.

Han Fei smiled politely at her, then got up and left the meeting room.