Very long-running buildworld process

From: bob prohaska <fbsd_at_www.zefox.net>
Date: Wed, 11 Jun 2025 03:59:14 UTC 
Buildworld for -current on a Pi2B is strangely slow. The machine is responsive,
but seems to make no (or very slow) progress:


login: Jun  7 22:51:31 www su[3032]: bob to root on /dev/pts/0


FreeBSD/arm (www.zefox.org) (ttyu0)

login: bob
Password:
Last login: Sat Jun  7 22:51:25 from gateway.zefox.net
FreeBSD 15.0-CURRENT #85 main-d8773fdcbfa3: Fri Jun  6 14:17:58 PDT 2025     bob@www.zefox.org:/usr/obj/usr/src/arm.armv7/sys/GENERIC

Welcome to FreeBSD!

Release Notes, Errata: https://www.FreeBSD.org/releases/
Security Advisories:   https://www.FreeBSD.org/security/
last pid: 34625;  load averages:    1.01,    1.01,    1.00                                                             up 2+22:03:17  20:45:47
last pid: 34628;  load averages:    1.07,    1.02,    1.01                                                             up 2+22:05:21  20:47:51
45 processes:  2 running, 43 sleeping
CPU: 25.0% user,  0.0% nice,  0.0% system,  0.0% interrupt, 75.0% idle
Mem: 6196K Active, 297M Inact, 174M Wired, 98M Buf, 443M Free
Swap: 1770M Total, 422M Used, 1348M Free, 23% Inuse

  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
21654 root          1 135    0   561M    17M CPU1     1  39.8H 100.12% c++
34626 bob           1  20    0  6664K  3064K CPU3     3   0:00   0.31% top
 2843 root          1  20    0  4684K   756K select   2   2:07   0.01% powerd
10915 root          1  20    0  7036K   824K select   1   0:08   0.00% make
 2934 root          1  28    0    13M  2408K select   0   4:39   0.00% sshd
16200 root          1  20    0    11M  3908K select   1   0:39   0.00% make
 2951 root          1  20    0    11M  1836K select   0   0:25   0.00% sendmail
 2719 root          1  20    0  5608K  1292K kqread   2   0:12   0.00% syslogd
 3085 root          1  20    0  6340K   864K select   0   0:08   0.00% make
11703 root          1  20    0  5968K   816K select   3   0:08   0.00% make
 3044 root          1  20    0  5920K   848K select   1   0:08   0.00% make
10901 root          1  20    0  6340K   824K select   0   0:08   0.00% make
 9496 root          1  20    0  6340K   820K select   0   0:08   0.00% make
 2946 root          1  20    0  5216K   944K nanslp   1   0:07   0.00% cron

Note the 38 hour runtime for PID 21654...

Buildworld output ends with:
...
Building /usr/obj/usr/src/arm.armv7/lib/clang/libclang/Tooling/JSONCompilationDatabase.pico
Building /usr/obj/usr/src/arm.armv7/lib/clang/libclang/Tooling/Refactoring.pico
Building /usr/obj/usr/src/arm.armv7/lib/clang/libclang/Tooling/RefactoringCallbacks.pico
Building /usr/obj/usr/src/arm.armv7/lib/clang/libclang/Tooling/Tooling.pico
root@www:/usr/src # 

Likely the culprit is one of those jobs.

Gstat reports occasional brief access to /dev/da0s2a, both the serial console
and the controlling ssh session for buildworld are responsive, the host isn't
crashed.

The buildworld command is
make -j4 -DWITH_META_MODE  KERNCONF=GENERIC  TARGET=arm TARGET_ARCH=armv7 buildworld > buildworld.log

Is there a graceful way to figure out what's going on? 

Thanks for reading,

bob prohaska