Fix MemoryError in Spring Boot

Spring Boot OutOfMemoryError

Spring Boot applications throw java.lang.OutOfMemoryError with different messages depending on which memory area is exhausted. Each requires a different fix.

Java Heap Space

The most common OOM. The heap is full of live objects:

# Increase heap
java -Xmx1g -Xms512m -jar app.jar

But increasing heap is a band-aid. Find the leak:

# application.yml — enable heap dump on OOM
JAVA_OPTS: >-
  -XX:+HeapDumpOnOutOfMemoryError
  -XX:HeapDumpPath=/tmp/heapdump.hprof

Metaspace

OutOfMemoryError: Metaspace means too many classes are loaded, often from reflection-heavy libraries:

java -XX:MaxMetaspaceSize=256m -jar app.jar

Thread Stack

Too many threads exhaust native memory:

# Reduce thread stack size (default 1MB)
java -Xss512k -jar app.jar

Also configure Tomcat's thread pool:

server:
  tomcat:
    threads:
      max: 100  # Down from default 200

Container-Aware JVM Settings

ENV JAVA_OPTS="-XX:+UseContainerSupport -XX:MaxRAMPercentage=75.0 -XX:+HeapDumpOnOutOfMemoryError"
CMD java $JAVA_OPTS -jar app.jar

Connection Pool Sizing

spring:
  datasource:
    hikari:
      maximum-pool-size: 10
      minimum-idle: 5

Each connection uses memory for buffers and result sets.

Bugsly captures OutOfMemoryError events with the specific memory area, thread dump, and recent request context, dramatically reducing investigation time.