Java互斥

Question

i just have a quick question about concurrent programming in Java. for example, i have a NxN matrix, and there is a corresponding thread for each row of the matrix, if there is no interaction between threads in each row, is it safe (or correct) if multiple threads access and modify separate rows of the matrix simultaneously? Thanks!!

Answer 1

If you are only doing reads of the matrix, it is always safe. If you are doing writes, but a thread only reads and writes to the row it is assigned, it is safe. It is only if you have a thread reading from a cell written by another thread that you have to worry about locks.

Answer 2

If you have a native 2d array, and not a wrapper class, then concurrent row access should be fine. As long as you never read/write or write/write to the same memory location, you're okay.

Answer 3

如果可以保证没有线程会改变任何其他线程读取或变异的元素，并且也没有线程会改变矩阵的尺寸，那么这是安全的。