Linux OOM Killer Terminated Process — Out of Memory and Memory Leak Detection

Fix the Linux OOM Killer terminating processes due to memory exhaustion, identify memory leaks, and configure memory limits to prevent OOM kills. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: The OOM (Out of Memory) Killer is a Linux kernel mechanism that terminates processes when memory is exhausted. OOM kills are logged in dmesg and kernel logs with the message 'Out of memory: Kill process'. The kernel selects which process to kill based on the oom_score (higher score = more likely to be killed). Memory overcommit (vm.overcommit_memory) allows allocating more memory than physically available. cgroups memory limits can prevent specific services from consuming all available memory. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Application memory leak gradually consuming all available RAM. Insufficient physical RAM for the workload (under-provisioned server). No swap space configured as a safety buffer for memory pressure. Multiple memory-hungry processes competing for limited RAM. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Check OOM events: 'dmesg -T | grep -i oom' or 'journalctl -k | grep -i oom'. Monitor memory usage in real-time: 'htop' or 'watch -n 1 free -h'. Find memory-hungry processes: 'ps aux --sort=-%mem | head -20'. Set memory limits with systemd: add MemoryMax=2G in the service file [Service] section. Add swap as safety buffer: 'fallocate -l 4G /swapfile && mkswap /swapfile && swapon /swapfile'. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

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