fix waitall, may terminate early.

Former-commit-id: dc7fbe6566032ee469ab0a2d36c10cca630ea51b

src/engine.c

@@ -744,9 +744,10 @@ int engine_exchange_strays ( struct engine *e , struct part *parts , struct xpar
     /* Wait for each part array to come in and collect the new
        parts from the proxies. */
     for ( k = 0 ; k < 2*(nr_in + nr_out) ; k++ ) {
-        if ( MPI_Waitany( 2*e->nr_proxies , reqs_in , &pid , &status ) != MPI_SUCCESS ||
-             pid == MPI_UNDEFINED )
+        if ( MPI_Waitany( 2*e->nr_proxies , reqs_in , &pid , &status ) != MPI_SUCCESS ) {
             error( "MPI_Waitany failed." );
+        if ( pid == MPI_UNDEFINED )
+            break;
         // message( "request from proxy %i has arrived." , pid );
         if ( reqs_in[pid & ~1] == MPI_REQUEST_NULL &&
              reqs_in[pid | 1 ] == MPI_REQUEST_NULL ) {

src/space.c

@@ -507,11 +507,11 @@ void space_rebuild ( struct space *s , double cell_max ) {
 void parts_sort ( struct part *parts , struct xpart *xparts , int *ind , int N , int min , int max ) {
 
     struct qstack {
-        int i, j, min, max;
+        volatile int i, j, min, max;
         volatile int ready;
         };
     struct qstack *qstack;
-    int qstack_size = (max-min)/2 + 1;
+    int qstack_size = (max-min)/2 + 10;
     volatile unsigned int first, last, waiting;
     
     int pivot;