Fei has over 10 years of development experience at Tencent and Sogou. Through this account, he shares his deep insights on performance.
This article explains how Redis initializes, creates a TCP listener, registers file events, runs a single‑threaded reactor loop, accepts client connections, processes commands via a command table, and sends replies, illustrating the core backend architecture of the in‑memory database.
The article explains why Linux reports "fork: cannot allocate memory" when the real issue is PID allocation failure caused by excessive threads, analyzes the kernel's do_fork and alloc_pid implementations, and shows that newer kernels still return ENOMEM for non‑memory errors.
This article explains how a CPU handles interrupts using mechanisms like the programmable interrupt controller (PIC), advanced APIC, interrupt vectors, IDT, and how interrupt affinity and CPU affinity can be configured to balance load across multiple cores, illustrating both synchronous exceptions and asynchronous interrupts.
This article provides a step‑by‑step methodology for identifying why a Redis instance becomes slow, covering baseline latency testing, slow‑log analysis, big‑key detection, expiration patterns, memory limits, fork overhead, huge‑page effects, AOF configuration, CPU binding, swap usage, memory fragmentation, network saturation, and practical remediation techniques.
This article narrates how two friends transform secret light‑bulb blink codes into binary representations, then progressively design logic gates, adders, a full‑adder, RAM, an ALU and a programmable control unit, illustrating the fundamentals of digital circuit design and automation.
This article explains the Linux SO_REUSEPORT feature introduced in kernel 3.9, how it allows multiple processes to bind and listen on the same port, the kernel's load‑balancing mechanism, and provides practical C examples and verification steps for developers.
This article provides a thorough introduction to the Domain Name System (DNS), covering its hierarchical design, query workflow, caching mechanisms, message structure, resource record types, and common security threats along with mitigation techniques, offering essential knowledge for networking fundamentals.
A dramatized Linux security incident shows how administrators use commands like top, ps, netstat, and the unhide tool to discover hidden mining processes, isolate suspicious network connections, and finally terminate the malicious hidden PID, illustrating practical techniques for rootkit detection and response.
This article explains how Linux servers handle binding to 0.0.0.0, detailing the internal mechanisms of socket binding, listening, and packet processing, with source code analysis to clarify the differences between binding to 0.0.0.0 versus specific IP addresses.
This article explains the fundamentals of Linux routing, why routing is required for containers and overlay networks, how the kernel selects routes when sending and receiving packets, and provides practical commands and code examples for configuring and testing routing tables in cloud‑native environments.
