Add _barrier to avoid race condition for share mem I/O

schism-dev · Dec 12, 2024 · afc1638 · afc1638
1 parent 1c88cac
commit afc1638
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Showing 3 changed files with 7 additions and 3 deletions.
diff --git a/src/Hydro/misc_subs.F90 b/src/Hydro/misc_subs.F90
@@ -823,8 +823,10 @@ subroutine other_hot_init(time)
         !First 2 vars are bcast from rank 0 of comm, which must be a member of myrank_node=0?
         call mpi_bcast(th_dt3,nthfiles3,rtype,0,comm,istat)
         call mpi_bcast(th_time3,2*nthfiles3,rtype,0,comm,istat)
-#ifndef SH_MEM_COMM
+#ifdef SH_MEM_COMM
         !For share mem, ath3 is already filled
+        call mpi_barrier(comm_node, istat)
+#else
         call mpi_bcast(ath3,max(1,nsources,nsinks)*ntracers*2*nthfiles3,MPI_REAL4,0,comm,istat)
 #endif
       endif 

diff --git a/src/Hydro/schism_step.F90 b/src/Hydro/schism_step.F90
@@ -1680,10 +1680,12 @@ subroutine schism_step(it)
             endif !if_source
           endif !time
         endif !nsinks
+
 !       Finished reading; bcast from rank 0 of comm (which must be a member of myrank_node=0)
         call mpi_bcast(th_time3,2*nthfiles3,rtype,0,comm,istat)
 #ifdef SH_MEM_COMM
-        ! ath3 data now in shared buffer, no longer necessary to broadcast
+        ! ath3 data in shared buffer, no longer necessary to broadcast
+        !Sync to ensure the buffer is filled
         call mpi_barrier(comm_node, istat)
 #else
         call mpi_bcast(ath3,max(1,nsources,nsinks)*ntracers*2*nthfiles3,MPI_REAL4,0,comm,istat)

diff --git a/src/Readme.beta_notes b/src/Readme.beta_notes
@@ -616,7 +616,7 @@ git versions:
 161. `ca44ba0` (1 May 2024): fixed bugs in vegetation&marsh module (uninited sav_h0 etc) 
 162. `cfb58a5` [5 July 2024] replace fatal errors with warning in btrack (no intersecting edges). These are exaordinary exceptions that occur rarely.
 163. `2f88fc5` (7 Aug 2024): changed horizontal diffusion method to filter;
-164. `` (Dec 2024): added share memory communicator for efficient bcast
+164. `c441ace` (12 Dec 2024): added share memory communicator for efficient bcast;
 
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