EC
NoMemoryError
RubyFATALCommonSystem

Memory allocation failed

Quick Answer

Investigate memory leaks, large data processing patterns, and process memory limits rather than rescuing this error.

What this means

Raised when memory allocation fails at the OS level. Because this error can fire during any allocation, it is almost impossible to handle gracefully. It is a subclass of Exception, not StandardError.

Why it happens
  1. 1Process reaching its memory limit (ulimit or container limit)
  2. 2Loading an extremely large dataset into memory at once
  3. 3Memory leak accumulating over a long-running process

Fix

Stream large data instead of loading it all

Stream large data instead of loading it all
# Instead of:
# data = File.read('huge.csv')   # entire file in memory

# Stream line by line:
File.foreach('huge.csv') do |line|
  process(line)
end

Why this works

Streaming processes one record at a time, keeping memory footprint constant regardless of file size.

Code examples
Triggering conditionruby
# Allocating an impossibly large array
arr = Array.new(10**12)
# NoMemoryError: failed to allocate memory
Streaming large filesruby
CSV.foreach('large.csv', headers: true) do |row|
  ImportJob.perform_later(row.to_h)
end
NoMemoryError is not StandardErrorruby
NoMemoryError < Exception    # => true
NoMemoryError < StandardError # => false  — bare rescue won't catch it
Sources
Official documentation ↗

Ruby Core Documentation

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