Chase Mao's blog

Limit Node Memory Usage

2024-07-29

Introduction

When compiling a React app with Node.js, the memory usage can exceed 1GB, which can cause a 2C2G (2 CPU cores, 2GB RAM) machine to crash. The Out-Of-Memory (OOM) killer in Linux doesn’t always work effectively, leading to the entire system becoming unresponsive.

This article aims to address two problems:

  1. Limiting Node.js memory usage.
  2. Ensuring the system remains responsive by effectively handling out-of-memory situations.

Limiting Memory Usage

Many posts suggest using the --max-old-space-size flag to limit Node.js memory usage. However, in my experience, this approach is not always effective. Instead, I recommend using cgroup to control memory usage.

  1. Install cgroup tools:

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    sudo apt-get install cgroup-tools

  2. Add the following commands to your ~/.bashrc or another shell script:

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    # Create a cgroup named 'node_group' with CPU and memory limits
sudo cgcreate -a $USER:$USER -t $USER:$USER -g cpu,memory:node_group

# Set CPU usage limit to 80% (80000 microseconds out of 100000)
sudo cgset -r cpu.cfs_quota_us=80000 node_group

# Set memory usage limit to 300MB
sudo cgset -r memory.limit_in_bytes=300M node_group

  3. Apply the changes:

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    source ~/.bashrc

  4. Run your command with cgroup:

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    cgexec -g cpu,memory:node_group your_command_here

    You can also set an alias for convenience:

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    alias run_with_limits='cgexec -g cpu,memory:node_group'

Recovering from Out of Memory

Linux provides an OOM killer mechanism to protect the system. In theory, when an OOM situation occurs, the kernel will choose a process to kill based on certain strategies. However, the implementation can be buggy. In my experiments, when an OOM situation occurs, the entire system becomes unresponsive, requiring a shutdown and restart.

To address this, I recommend using earlyoom. It employs a more aggressive strategy to start killing processes before the system runs out of memory entirely, ensuring the OOM killer can still function.

  1. Install earlyoom:

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    sudo apt-get install earlyoom

  2. Configure earlyoom (Optional):

    • Edit the configuration file (usually located at /etc/default/earlyoom or /etc/earlyoom.conf): 
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      # Example configuration
# Kill processes when both RAM and swap are below 10%
EARLYOOM_ARGS="-r 10 -s 10"

  3. Start earlyoom:

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    sudo systemctl enable earlyoom
sudo systemctl start earlyoom

Summary

By following these steps, you can limit Node.js memory usage effectively and ensure your system remains responsive even when memory is running low. This setup will help you avoid system crashes and maintain a stable development environment.