Understanding Java Virtual Machines-non-heap related parameter settings (4)

Non-heap memory-related configuration-xx:permsize

Initial size of the permanent zone

-xx:maxpermsize

Maximum size of the permanent zone use-xx:mxmetaspacesize to configure the maximum size of the JDK1.8 in the

-xss

Thread stack size

-xx:maxdirectmemorysize

The direct memory size, which defaults to the maximum heap space, which is-xmx. When the direct memory usage reaches-xx:maxdirectmemorysize, garbage collection is triggered, and if garbage collection does not effectively free up space, a direct memory overflow will still cause the system to oom. In general, direct memory reads and writes faster than heap memory, but requests are slower than heap memory. Direct memory is suitable for scenarios where the number of applications is low and read and write frequently.

Working mode of the JVM

Server mode is slower to start than client mode because the server mode tries to collect more system performance information and optimizes the program with more sophisticated optimization algorithms. Therefore, when the system is fully up and running stable, the server mode executes much faster than the client mode.

-client-server

Understanding Java Virtual Machines-non-heap related parameter settings (4)