# Stall in some multi-node parallel calculations **URL:** https://community.freefem.org/t/stall-in-some-multi-node-parallel-calculations/1143 **Category:** General Discussion **Created:** [August 6, 2021, 11:36am UTC](https://community.freefem.org/t/stall-in-some-multi-node-parallel-calculations/1143 "2021-08-06T11:36:47Z") **Posts on this page:** 1 **Showing post:** 76
### Author: ![etj](https://avatars.discourse-cdn.com/v4/letter/e/a698b9/32.png) [@etj](https://community.freefem.org/u/etj) #### Post date: [August 13, 2021, 12:14pm UTC](https://community.freefem.org/t/stall-in-some-multi-node-parallel-calculations/1143/76 "2021-08-13T12:14:54Z")
Now, although I have not modified `macro_ddm.idp` further, I can’t reproduce the error about `intersection`… The output is the following with the `-ns` flag: ```auto -- FreeFem++ v4.9 (Fri Jun 18 14:45:02 CEST 2021 - git v4.9) Load: lg_fem lg_mesh lg_mesh3 eigenvalue parallelempi load: init metis (v 5 ) sizestack + 1024 =10824 ( 9800 ) -- Square mesh : nb vertices =1681 , nb triangles = 3200 , nb boundary edges 160 -- Square mesh : nb vertices =1681 , nb triangles = 3200 , nb boundary edges 160 -- Square mesh : nb vertices =1681 , nb triangles = 3200 , nb boundary edges 160 -- Square mesh : nb vertices =1681 , nb triangles = 3200 , nb boundary edges 160 2 true neighbor is 1 (1) 2 true neighbor is 3 (2) 2: 2 1 3 190 426 rank 2 sending/receiving 190 to 1 --- global mesh of 4800 elements (prior to refinement) partitioned with metis --metisA: 4-way Edge-Cut: 3, Balance: 1.01 Nodal=0/Dual 1 (in 4.319191e-03) 0 true neighbor is 1 (1) --- partition of unity built (in 2.465439e-01) 0: 1 1 480 rank 0 sending/receiving 480 to 1 1 true neighbor is 0 (1) 1 false neighbor bis is 2 (1) 1 true neighbor is 3 (2) 1: 2 0 3 480 964 rank 1 sending/receiving 480 to 0 rank 1 sending/receiving 964 to 3 3 true neighbor is 1 (1) 3 true neighbor is 2 (2) 3: 2 1 2 964 426 rank 3 sending/receiving 964 to 1 rank 3 sending/receiving 426 to 2 rank 0 received from 1 (1) with tag 0 and count 480 rank 2 sending/receiving 426 to 3 rank 1 received from 0 (0) with tag 0 and count 480 rank 2 received from 3 (3) with tag 0 and count 426 rank 1 received from 3 (3) with tag 0 and count 964 rank 3 received from 2 (2) with tag 0 and count 426 rank 3 received from 1 (1) with tag 0 and count 964 ``` and without the `-ns` flag: ```auto (...) 41 : sizestack + 1024 =10824 ( 9800 ) -- Square mesh : nb vertices =1681 , nb triangles = 3200 , nb boundary edges 160 -- Square mesh : nb vertices =1681 , nb triangles = 3200 , nb boundary edges 160 --- global mesh of 4800 elements (prior to refinement) partitioned with metis --metisA: 4-way Edge-Cut: 3, Balance: 1.01 Nodal=0/Dual 1 (in 4.315138e-03) 0 true neighbor is 1 (1) --- partition of unity built (in 2.509263e-01) 0: 1 1 480 rank 0 sending/receiving 480 to 1 1 true neighbor is 0 (1) 1 false neighbor bis is 2 (1) 1 true neighbor is 3 (2) 1: 2 0 3 480 964 rank 1 sending/receiving 480 to 0 rank 1 sending/receiving 964 to 3 rank 0 received from 1 (1) with tag 0 and count 480 2 true neighbor is 1 (1) 2 true neighbor is 3 (2) 2: 2 1 3 190 426 rank 2 sending/receiving 190 to 1 rank 2 sending/receiving 426 to 3 rank 1 received from 0 (0) with tag 0 and count 480 rank 1 received from 3 (3) with tag 0 and count 964 3 true neighbor is 1 (1) 3 true neighbor is 2 (2) 3: 2 1 2 964 426 rank 3 sending/receiving 964 to 1 rank 3 sending/receiving 426 to 2 rank 2 received from 3 (3) with tag 0 and count 426 rank 3 received from 2 (2) with tag 0 and count 426 rank 3 received from 1 (1) with tag 0 and count 964 ``` --- _[View the full topic](https://community.freefem.org/t/stall-in-some-multi-node-parallel-calculations/1143)._