Unfortunate about the mimalloc 2.x segfaults on Alpine Linux with Tor. Looking forward to your results with jemalloc, which also worked well for us. We haven’t researched root causes, allocator parameters, build-time changes, or mozjemalloc yet. It would be great to see more relay operators sharing more experiments and data points. In addition to the Ubuntu 24.04 experiment, we also ran a 10-day test on Debian 13.2. The outcome was the same: mimalloc 2.0.9 and 2.1.7 both performed very well. We compiled both locally, which was quick and straightforward. Interestingly, mimalloc 3.0.1 performed worse on Debian 13.2 (where it ships by default), with continued memory growth compared to Ubuntu 24.04. We posted a brief follow-up blog with a chart here: https://www.1aeo.com/blog/mimalloc-209-tor-relay-deployment.html We’ve started migrating our guard relays to mimalloc 2.1.2 (Ubuntu 24.04 default) or 2.0.9 (compiled on Debian 13.2). The memory savings have been substantial: roughly 200 relays now consume ~300 GB total instead of ~1000 GB, which is a significant operational cost difference. On Friday, January 9th, 2026 at 2:34 PM, forest-relay-contact--- via tor-relays <tor-relays@xxxxxxxxxxxxxxxxxxxx> wrote: > > > Hello. > > Unfortunately, mimalloc2 appears to be useless on stock Alpine Linux, > causing repeated segmentation faults that crash Tor after a short time: > > [74497.456152] tor[2942]: segfault at 2ba16010000 ip 00007f42d17d7da0 sp 00007f42cbf1b558 error 6 in libmimalloc-secure.so.2.2[15da0,7f42d17c6000+1f000] likely on CPU 0 (core 0, socket 0) > [74497.456168] Code: 49 f7 d9 48 31 f8 48 d3 c0 48 01 c8 49 89 01 48 8d 04 32 48 89 c2 48 8b 4f 38 48 33 47 40 49 89 f1 49 f7 d9 48 d3 c0 48 01 c8 <4a> 89 94 0a 49 39 d0 73 dc 48 8b 47 10 48 8b 4f 38 48 85 c0 48 0f > > > As this is occurring with mimalloc2 while mimalloc3 is the latest, and > considering mimalloc3 does not show such heavy memory savings, I'm not > going to be putting any effort into debugging this. > > I'm trying out jemalloc now. If this can help reduce some of the high > memory pressure on this 512 MiB VPS, that would be very nice. > > Regards, > forest
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