Key Features of htop

Process List

• Displays all running processes along with details like PID, user, CPU%, MEM%, and command.
• Sorting:
  • Use F6 to sort by columns (e.g., CPU%, MEM%, TIME+).
  • Sorting is essential for identifying high-resource-consuming processes.

Real-Time CPU and Memory Monitoring

• CPU Usage: Shown as bars at the top, indicating per-core usage.
• Memory and Swap Usage: Displayed next to CPU, helps detect memory bottlenecks.

Load Average

• Found in the top-right corner (1.00, 5.00, 15.00).
  • Indicates average system load over the last 1, 5, and 15 minutes.
  • Compare to the number of CPU cores:
    • Load <= cores: System is performing well.
    • Load > cores: CPU is overloaded.

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Navigating htop

Basic Shortcuts

Key	Function	Use Case
F1	Help	Shows htop help documentation.
F2	Setup	Customize the htop interface.
F3	Search	Find specific processes (e.g., nginx).
F4	Filter	Filter processes by keyword (global search).
F5	Tree View	View parent-child process hierarchy. Useful for debugging dependencies.
F6	Sort	Sort processes by column (CPU%, MEM%, etc.).
F9	Kill	Terminate a process (requires permissions).

Searching and Filtering

• F3 (Search): Quickly find a specific process by name.
• F4 (Filter): Enter a keyword to display only relevant processes.

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Advanced Process Analysis

Tree View

• Toggle with F5 to visualize parent-child relationships.
• Use this to trace a root process and its spawned sub-processes.

Inspecting a Process

• Highlight a process using the arrow keys and press Enter.
• This will display additional options (not detailed inspection). For in-depth analysis:
  • Use strace for system call tracing:bash复制代码sudo strace -p <PID>
  • Use lsof to view open files:bash复制代码sudo lsof -p <PID>

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Understanding System Bottlenecks

Identifying High CPU or Memory Processes

• Sort by CPU% or MEM% using F6.
• Focus on processes with unusually high percentages.

Checking System Load

• Use the load average to assess system stress:
  • Rule of Thumb: Load should be ≤ number of cores.

Debugging CPU Overload

• Identify which processes are consuming CPU the most.
• Check process hierarchy with F5 (Tree View) to trace dependencies.

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Real-Life Use Cases

Empty System Analysis

• Look for idle CPU usage to determine the baseline load.
• Compare with loaded conditions to identify which processes contribute most.

Diagnosing Memory Bottlenecks

• Monitor MEM% to identify memory-intensive processes.
• Check swap usage to determine if memory pressure is high.

Testing Hypotheses

• Gradually disable or terminate suspected processes to observe CPU/MEM impact.

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Tips for Efficient htop Usage

1. Custom Columns: Use F2 to add or remove columns for tailored views.
2. Log Data: Combine with htop > logfile.txt for offline analysis.
3. Automate Reports: Use htop with cron or scripts to capture snapshots periodically.

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htop is an essential tool for Linux system monitoring. With its user-friendly interface and powerful features, freshers can quickly become proficient in identifying and addressing system performance issues. Happy analyzing!