Can't build lang/rust with synth

Hello,

Trying to build lang/rust (with default options) with synth (synth-3.12) under 14.3-RELEASE-p7, and after some 40-50 minutes the system becomes unresponsive due to out of swap. This is a VM with 8vCPU and 32GB of RAM (8GB is assigned to swap) on a SSD datastore.

FreeBSD BUILDX 14.3-RELEASE-p7 FreeBSD 14.3-RELEASE-p7 releng/14.3-n271455-8b2a912a8abd

Tried to reduce Number_of_builders and Max_jobs_per_builder, and set Tmpfs_workdir and Tmpfs_localbase to false, but none of it helped.

Any tips would be appreciated. Thank you.

Code:
[Global Configuration]
profile_selected= LiveSystem

[LiveSystem]
Operating_system= FreeBSD
Directory_packages= /synth/live_packages
Directory_repository= /synth/live_packages/All
Directory_portsdir= /usr/ports
Directory_options= /var/db/ports
Directory_distfiles= /usr/ports/distfiles
Directory_buildbase= /synth/synth-live
Directory_logs= /synth/log
Directory_ccache= /ccache
Directory_system= /
Number_of_builders= 4
Max_jobs_per_builder= 2
Tmpfs_workdir= false
Tmpfs_localbase= false
Display_with_ncurses= true
leverage_prebuilt= false
 
Did you turn on DEBUG for the build?

32 GB should be enough for 4 cores plus hyperthreading = 8 vCPU.

I haven't measured how much RAM a non-DEBUG build of Rust needs lately. I varies quite a bit during the build. The linking stage is a killer.
 
Did you turn on DEBUG for the build?

32 GB should be enough for 4 cores plus hyperthreading = 8 vCPU.

I haven't measured how much RAM a non-DEBUG build of Rust needs lately. I varies quite a bit during the build. The linking stage is a killer.

No, DEBUG isn't enabled, only defaults DOCS, SOURCES and WASM are.

My last successful build of rust (rust-1.91.1) was on November 20, 2025 on the same server.
 
I have 16GB physical memory and 32GB of swap space with 4c8t cpu and i can build rust too within an hour, however i don't have the latest rust yet but 1.91.1. If you want to use some programs when rust is building, left yourself some free cpu core, that works for me with cpuset. If you keep the machine spare and just wait, and it is still unresponsive, i don't know but may sound like a problem.

Do you use ZFS? maybe limiting the arc size would help if it's consuming too much. I have set it to 2G max.

Code:
yusuf@freebsd:~ % grep zfs /boot/loader.conf
zfs_load="YES"
vfs.zfs.arc.max="2G"

I use poudriere instead of synth btw.
 
Trying to build lang/rust (with default options) with synth (synth-3.12) under 14.3-RELEASE-p7, and after some 40-50 minutes the system becomes unresponsive due to out of swap.
What else is building besides rust? There may be some other jobs running concurrently. Those will use up resources too.
 
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