daemon/worker: drop caching of kr_request mempools

This caused a huge increase in real memory usage in case of queries arriving to kresd while being disconnected from internet. The usage was slowly creeping up, even over 2G.

Interesting past commits: b350d38d and two preceding.

There apparently was no real memory leak. I assume that reusal of long-living mempools is risky in terms of memory fragmentation, though the extent of the issue surprised me very much. The issue seemed the same with normal glibc and jemalloc.

I generally dislike ad-hoc optimization attempts like these freelists. Now the allocator can better decide itself how to reuse memory.

added performance label

approved this merge request

To be safe, let me do at least some simple manual measurement confirming that this doesn't do a significant regression for CPU time.

resolved all threads

added 20 commits

• d9e75f3e...7f07e75a - 18 commits from branch master
• 8ef99b1b - daemon/worker: drop a long unused #define
• 17815ff3 - daemon/worker: drop caching of kr_request mempools

Compare with previous version

merged

mentioned in commit a4f522b8