IntelliJ IDEA: java.lang.OutOfMemoryError: insufficient memory When Running or Building a Spring Project

Summary

When building or running a Spring project from IntelliJ IDEA, the IDE may fail with the error:

java.lang.OutOfMemoryError: insufficient memory

This error has two common causes: insufficient heap allocated to IntelliJ IDEA's shared build process, or a 32-bit JDK configured as the project SDK. Check both, starting with the heap size.

Symptoms

• Build or run fails immediately or during compilation
• Error appears in the Build output or Run console
• The compiler error may be prefixed with java: (for example, java: OutOfMemoryError: insufficient memory)
• The error message may alternate between Java heap space and insufficient memory as the configured heap value changes
• Project worked previously without issues
• Updating IntelliJ IDEA does not resolve the problem

Root Cause

IntelliJ IDEA uses a separate JVM (shared build process) to compile and build projects. This process has its own heap size limit, which is independent of:

• The IDE heap size
• The application (Spring Boot) runtime heap size

There are two independent reasons this JVM can fail with an out-of-memory error:

1. The shared build process heap is too small. Over time, memory requirements can increase due to project growth, additional modules or dependencies, annotation processing (e.g., Lombok, MapStruct), or JDK/IDE updates that change compiler behavior. A previously sufficient value (e.g., 700 MB) may no longer be adequate.

2. The project SDK is a 32-bit JDK. When the project SDK differs from the IDE's runtime, the Java compiler runs as a separate forked process using the project's JDK. A 32-bit JVM on Windows can address only about 1.3–1.5 GB of heap regardless of the configured -Xmx. In this case, increasing any heap setting does not help, because the compiler cannot use more than the 32-bit limit. Requesting a heap larger than a 32-bit process can reserve changes the error from Java heap space to insufficient memory. A 32-bit JDK is installed under C:\Program Files (x86)\, while a 64-bit JDK is installed under C:\Program Files\.

Resolution

Step 1: Increase the shared build process heap size

1. Open File → Settings (or Ctrl + Alt + S)

2. Navigate to Build, Execution, Deployment → Compiler

3. Increase Shared build process heap size

   • Example: change from 700 MB to 1400 MB (a value of 2048–4096 MB is sufficient for most projects)

4. Click Apply and OK

5. Restart IntelliJ IDEA

   

Step 2: Verify the project SDK is a 64-bit JDK

If increasing the heap has no effect, check whether the project SDK is a 32-bit JDK.

1. Open File → Project Structure → Project
2. Inspect the configured SDK path. A path under C:\Program Files (x86)\ indicates a 32-bit JDK.
3. Select a 64-bit JDK. If none is installed, use Add SDK → Download JDK in the same dialog. The same Java version is fine; only the 64-bit build is required.
4. Rebuild the project.

A 64-bit JDK can use a large heap, so the build process and forked compiler are no longer limited to ~1.3–1.5 GB.