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Out of memory issue in a Node.js app based on Docker

Problem​

  • When running a node.js app based on Docker, the server encountered an out of memory issue while it was running.
  • For the v8 engine of node.js, the limit of heap memory is set by default. It has the following limit capacity of heap memory.
    • Below v12: 1.35GB
    • Below v14: 2GB
    • v14 and above: 4GB
  • The app continued to use memory and the service died because we didn't know about this memory limit.
  • The instance of this service had 12GB of RAM, and when a lot of memory was being used, 4GB was used, leaving more than 7GB of free space.
  • We didn't fully understand the structure of the service, resulting in memory waste and reduced availability of the service.

Solution​

  • When running node, add --max-old-space-size=8192 start.js to increase the maximum heap of the program.
  • For Docker, add the environment variable NODE_OPTIONS=--max-old-space-size=8192.
  • By adding the above options, the maximum heap of the program increases, improving the availability of the service.