Memory usage in Java

Run a Java programCodeThe main memory consumption is as follows:

1. Heap

2. STACK: the stack is one for each thread, and the memory consumed is the memory size * Number of threads. Be careful when there are many threads.

3. Direct Memory: It mainly refers to the Cache during the channel. If the memory is insufficient, an outofmemoryerror error will also be reported, with sun outside. misc. unsafe. allocatememory exception (I think this is similar to the malloc function in C ).

4. the cache and buffer of the socket are not allocated in the heap. When the buffer cannot be allocated, the too program open files error is reported.

5. In JNI code, the code memory executed by the class library is no longer heap.

6. Virtual Machine execution also consumes a certain amount of memory.