我面臨著由於過度使用內存而被殺死的問題sort，並且無法理解為什麼它大大超出了給定的限制。
Context:
Available physical RAM: 8GB
Memory in use by system: <500MB (FreeBSD 13)
Free memory: ~7.5GB
Swap: 2G
No system hard limit on mem usage ($ ulimit -> unlimited)
File being sorted: 300+ GB
HDD space: 1Tb+ free both on target or temporary dir.
即使當我運行排序時指定可用資源限制；或沒有任何明確參數（應自動設定為可用的 90%），它最終會因過度使用而被殺死。
[mario@casa-server ~/pjy]$ sort -S 7G -T /filesWD-WMAY03648941/tmp/ -o /filesWD-WMAY03648941/pjA-sorted.txt pjyA.txt
Killed
[mario@casa-server ~/pjy]$
[mario@casa-server ~/pjy]$ sort -T /filesWD-WMAY03648941/tmp/ -o /filesWD-WMAY03648941/pjA-sorted.txt pjyA.txt
Killed
[mario@casa-server ~/pjy]$
顯然它確實超出了資源限制。當使用 -S 3G 運行時，我有時可以觀察到大約 5G 的使用量。
# ~5G USAGE EVEN WITH EXPLICIT -S 3G LIMIT
[mario@casa-server ~]$ sudo procstat -r 3183
PID COMM RESOURCE VALUE
3183 sort user time 00:27:51.849171
3183 sort system time 00:03:28.220262
3183 sort maximum RSS 5423072 KB
3183 sort integral shared memory 10505728 KB
3183 sort integral unshared data 1910064 KB
3183 sort integral unshared stack 30560128 KB
3183 sort page reclaims 8172561
3183 sort page faults 1724
3183 sort swaps 0
3183 sort block reads 24296
3183 sort block writes 17719
3183 sort messages sent 0
3183 sort messages received 0
3183 sort signals received 0
3183 sort voluntary context switches 5868
3183 sort involuntary context switches 30700
[mario@casa-server ~]$
# TOP excerpt
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
3183 mario 1 103 0 4657M 4603M CPU3 3 38:23 99.88% sort -S 3G -T /filesWD-WMAY03648941/tmp/ -o /files
# NO SO LIMIT ON USAGE
[mario@casa-server ~]$ sudo procstat -l 3183
PID COMM RLIMIT SOFT HARD
3183 sort cputime infinity infinity
3183 sort filesize infinity infinity
3183 sort datasize 32768 MB 32768 MB
3183 sort stacksize 524288 KB 524288 KB
3183 sort coredumpsize infinity infinity
3183 sort memoryuse infinity infinity
3183 sort memorylocked 65536 B 65536 B
3183 sort maxprocesses 12186 12186
3183 sort openfiles 234576 234576
3183 sort sbsize infinity infinity
3183 sort vmemoryuse infinity infinity
3183 sort pseudo-terminals infinity infinity
3183 sort swapuse infinity infinity
3183 sort kqueues infinity infinity
3183 sort umtxp infinity infinity
[mario@casa-server ~]$
[mario@casa-server ~]$ ulimit
unlimited
這就解釋了為什麼它在以 7G 限制（7.5 可用）運行時被殺死，或者當限制被自動設定時：它確實超過了使用所有 mem+swap（並且按預期被操作系統殺死）。
但我在這裡缺少什麼？man sort：
-S size, --buffer-size=size
Use size for the maximum size of the memory buffer. Size
modifiers %,b,K,M,G,T,P,E,Z,Y can be used. If a memory limit is
not explicitly specified, sort takes up to about 90% of available
memory. If the file size is too big to fit into the memory
buffer, the temporary disk files are used to perform the sorting.
如果-S 3G設定了，為什麼會超過使用RAM而不是HDD臨時資料夾？
PS：我試著問這個與其他「因記憶體不足而被殺」相關的問題，但有些版主管理不善。我確實認為這是一個相關的問題（將其標記為不相關的問題只會使解決方案支離破碎）。另外，我閱讀了許多其他可能的解決方案，但它們不適合這種情況。
謝謝大家