OutOfMemoryError: GC Overhead Limit Exceeded

Question:

I am receiving a "java.lang.OutOfMemoryError: GC overhead limit exceeded" error in a program that creates several HashMap objects with small text entries. Is there a programmatic alternative to increasing the heap size or disabling the error check?

Answer:

Yes, several programmatic alternatives can address this issue:

• Manage Batch Size: Work with smaller batches of HashMap objects to process simultaneously. This reduces the memory load on the garbage collector.
• Identify Duplicate Strings: Use the String.intern() method on duplicate strings before adding them to the HashMap. This ensures that only one copy of each string is stored in memory, freeing up space.
• Optimize HashMap Initialization: Use the HashMap(int initialCapacity, float loadFactor) constructor to specify the initial capacity and load factor of the HashMap. This helps optimize memory usage and reduce the likelihood of triggering the GC overhead limit.
• Implement WeakHashMap: Consider using a WeakHashMap. Unlike a regular HashMap, a WeakHashMap does not prevent its keys from being garbage collected. This can prevent memory leaks and reduce the load on the GC.

Note that using the HashMap.clear() method will indeed clear the data stored in the HashMap, rendering it unusable for the intended purpose. Therefore, it is not a recommended solution.