Caching technology and object pooling: a complement to Java caching technology

In Java development, caching technology is one of the commonly used optimization methods. For some frequently operated objects, cache can store them in memory to avoid the overhead of repeatedly creating and destroying objects, thereby improving program performance. However, caching also has some potential problems, such as it may cause the program to crash due to taking up too much memory. At this time, object pooling becomes a feasible solution.

1. Caching technology

Caching is usually implemented using HashMap or ConcurrentHashMap. When an object needs to be used, the program first checks whether the object already exists in the cache. If it exists, the object is taken directly from the cache and used; otherwise, the program needs to create a new object. When an object is no longer used, it is typically placed back into the cache for next use.

Compared with frequently creating and destroying objects, caching can reduce program overhead and improve program performance. However, caching will also bring some problems:

• The cache may occupy too much memory space, causing the program to crash
• The cached objects may expire and need to be checked and cleaned regularly
• Cache needs to consider concurrent access issues

2. Object pool

For some objects that are frequently created and destroyed, use an object pool to manage these objects Can reduce program overhead. The object pool avoids the overhead of repeatedly creating and destroying objects by creating a certain number of objects in advance and directly taking the objects from the pool for use when needed.

Object pools are usually implemented using blocking queues. When an object needs to be used, the program first removes the object from the queue. If the queue is empty, a new object needs to be created. When an object is no longer used, it is put back into the queue for next use.

Unlike caching, the object pool does not need to deal with the possible expiration of objects. However, object pools need to consider concurrent access issues. Because multiple threads may take and put objects back from the queue at the same time, thread-safe queues and locks need to be used to ensure thread safety.

3. Supplement to Java cache technology: using object pools to manage caches

The technology of combining cache and object pools can make up for the shortcomings of cache technology to a certain extent and fully Take advantage of caching and object pooling. The implementation method is as follows:

• Create a certain number of objects in advance and put them into the object pool
• Encapsulate the object pool as a cache class and use ConcurrentHashMap to save the cache
• When you need to use the cache, first check whether the object exists from ConcurrentHashMap. If it does not exist, take the object from the object pool and put it into ConcurrentHashMap. If the object pool is empty, you need to create a new object
• When the object is no longer used, remove it from the ConcurrentHashMap and put it back into the object pool

This kind of This method can solve the problem that the cache may expire, and also avoids the overhead of frequently creating and destroying objects. However, you need to pay attention to controlling the number of objects in the object pool to avoid taking up too much memory space. At the same time, because ConcurrentHashMap is thread-safe, it can avoid problems with concurrent access.

4. Summary

Java caching technology is one of the commonly used optimization methods, which can reduce program overhead and improve program performance. However, the cache also has some potential problems, such as it may occupy too much memory space and cause the program to crash. Object pools can be used as a supplement to caching technology. For some objects that are frequently created and destroyed, using object pools to manage these objects can reduce program overhead. Finally, combining the technology of cache and object pool can give full play to the advantages of cache and object pool, while solving the problem that cache may expire. This method is more suitable for some application scenarios.

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