Shared memory difference between 18.04 and 20.04

WallyZ

11/22/22, 12:09 AM

I'm having trouble with apps using shared memory in 21.04 that worked OK on 18.04.

One of the issues is the shared memory no-longer appears with ipcs. (It definitely shows in 18.04)

$ ./ovcc &
$ ps -ae | grep ovcc
  47730 pts/1    00:04:45 ovcc
$ sudo ipcs -m -p

------ Shared Memory Creator/Last-op PIDs --------
shmid      owner      cpid       lpid      
65539      wallyz     2417       47820     
32772      wallyz     2653       47820     
32775      wallyz     4322       47820     
8          wallyz     2359       47820     
32777      wallyz     2512       47820     
11         wallyz     2383       47820     
14         wallyz     2417       47820     
22         wallyz     2532       47820     
25         wallyz     2442       47820     
30         wallyz     2359       47820     
33         wallyz     2423       47820     
32802      wallyz     2963       47820     
32803      wallyz     2963       47820     
32804      wallyz     2963       47820     
37         wallyz     2419       47820     
32806      wallyz     2963       47820     
40         wallyz     2402       47820     
41         wallyz     2402       47820     
43         wallyz     2368       47820     
32812      wallyz     47668      47820     
47         wallyz     2963       47820     
48         wallyz     2963       47820     
53         wallyz     3611       47820     
56         wallyz     2963       47820     
57         wallyz     2963       47820     
58         wallyz     2963       47820     
59         wallyz     2963       47820     
62         wallyz     2495       47820     

$

So the process id 47730 doesn't appear in the list anywhere.

This leads to my main issue which is if my app segfaults the OS doesn't appear to be releasing the shared memory and now I have no way of manually identifying and removing the shared memory.

So what new mechanism is 20.04 using for shared memory and how do I manage it?

0 + 0

ram

20.04

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Shared memory difference between 18.04 and 20.04

TH: ความแตกต่างของหน่วยความจำที่ใช้ร่วมกันระหว่าง 18.04 และ 20.04

RO: Diferența de memorie partajată între 18.04 și 20.04

RU: Разница в общей памяти между 18.04 и 20.04

VI: Chênh lệch bộ nhớ dùng chung giữa 18.04 và 20.04

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