LINUX Server Reboot Frequency 7373

This used to be true, but no longer. Large chunks are given back to the system. This program:

main() { char *p = malloc(1024*1024); free(p); p = malloc(1024*1024); free(p); p = malloc(1024*1024); free(p); }

mmap2(NULL, 1052672, PROTREADPROTWRITE, MAPPRIVATEMAPANONYMOUS, -1, 0) = 0xb7ed5000 munmap(0xb7ed5000, 1052672) = 0 mmap2(NULL, 1052672, PROTREADPROTWRITE, MAPPRIVATEMAPANONYMOUS, -1, 0) = 0xb7ed5000 munmap(0xb7ed5000, 1052672) = 0 mmap2(NULL, 1052672, PROTREADPROTWRITE, MAPPRIVATEMAPANONYMOUS, -1, 0) = 0xb7ed5000 munmap(0xb7ed5000, 1052672) = 0

I do not know if unlimited free memory can be held if the program issues many small mallocs and then frees them Glibc tries to give back some memory if it has much free. However, this is not always possible. Smaller chunks are allocated by growing the data segment (or bss?), and if the last chunk is in use, it cannot create holes in the memory map.

I guess Oracle does not use Glibc's malloc and free, but implements its own memory management. It is quite possible that Oracle is optimized for "owning" the computer. If memory at some point is available, why give it up and later perhaps not get it again? Better keep it. Let the other programs have the trouble.

-Enrique