Understanding and Resolving java.lang.OutOfMemoryError: Kill process (java) or sacrifice child

When a container or device runs out of RAM, the Linux kernel’s OOM Killer terminates memory‑hungry processes to free resources; if the terminated process is a Java application, the JVM throws java.lang.OutOfMemoryError: Kill process (java) or sacrifice child . This error is not raised directly by the JVM but by the kernel when physical memory and swap are exhausted.

The root cause is system‑level memory shortage, with common contributors including:

Too many processes running on the host, leaving insufficient memory for the Java app.

Mismatched initial and maximum heap sizes (e.g., -Xms much smaller than -Xmx ), causing the heap to grow until RAM runs out.

Native memory growth even when -Xms equals -Xmx , as JVM native allocations can increase.

Application memory leaks in native memory or off‑heap objects such as DirectByteBuffer .

To resolve the error, consider the following measures:

Increase the host’s RAM capacity.

Terminate or migrate other processes to free memory for the Java application.

Set the initial and maximum heap sizes to the same value (e.g., -Xms = -Xmx ) so the JVM allocates the full heap at startup.

Fix native memory leaks, such as thread or direct buffer leaks.

Limit native memory usage with -XX:MaxDirectMemorySize .

Optimize Metaspace size using -XX:MaxMetaspaceSize to prevent unlimited growth.

Adjust OOM Killer behavior by modifying /proc/sys/vm/overcommit_memory or setting a lower oom_score_adj for the Java process.

For troubleshooting, you can:

Check kernel logs with dmesg -T to see if the OOM Killer terminated the Java process.

Apply the above remediation steps once the out‑of‑memory condition is confirmed.