From c8155acff7a62184c34e66a661152c7e2ca6cbbc Mon Sep 17 00:00:00 2001
From: Pedro Gonnet <gonnet@google.com>
Date: Thu, 1 Nov 2018 10:48:01 +0100
Subject: [PATCH] fix comments, turns out calling mpi_waitany on the same array
concurrently is illegal.
---
src/proxy.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/src/proxy.c b/src/proxy.c
index ed42717d1c..d28f3d3b33 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -328,6 +328,11 @@ void proxy_cells_wait_and_unpack_mapper(void *unused_map_data, int num_elements,
int pid = MPI_UNDEFINED;
MPI_Status status;
int res;
+
+ /* We need a lock to prevent concurrent calls to MPI_Waitany on
+ the same array of requests since this is not supported in the MPI
+ standard (v3.1). This is not really a problem since the threads
+ would block inside MPI_Waitany anyway. */
lock_lock(&data->lock);
if ((res = MPI_Waitany(data->num_proxies, data->reqs_in, &pid, &status)) !=
MPI_SUCCESS ||
@@ -336,6 +341,7 @@ void proxy_cells_wait_and_unpack_mapper(void *unused_map_data, int num_elements,
if (lock_unlock(&data->lock) != 0) {
error("Failed to release lock.");
}
+
// message( "cell data from proxy %i has arrived." , pid );
for (int count = 0, j = 0; j < data->proxies[pid].nr_cells_in; j++)
count += cell_unpack(&data->proxies[pid].pcells_in[count],
@@ -435,9 +441,6 @@ void proxy_cells_exchange(struct proxy *proxies, int num_proxies,
tic2 = getticks();
/* Wait for each pcell array to come in from the proxies. */
- /* TODO(pedro): This struct currently contains a lock to avoid calling
- MPI_Waitany in parallel (https://github.com/open-mpi/ompi/issues/6004).
- This should be removed once this works corectly in OpenMPI and IntelMPI. */
struct wait_and_unpack_mapper_data wait_and_unpack_data = {
s, num_proxies, reqs_in, proxies, with_gravity, lock_static_initializer};
threadpool_map(&s->e->threadpool, proxy_cells_wait_and_unpack_mapper,
--
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