hackbench: Wait for each child explicitly by using waitpid()

Quite often it's experienced in rteval that hackbench leaves some children
as zombies during closure.  This is an attempt to keep an overview of the
status of each child separately.  It's solved by having an array with all
sender and reciever children's pids and calling waitpid() on each of these
children pairs.

Signed-off-by: David Sommerseth <davids@redhat.com>

1 files changed, 29 insertions, 7 deletions

diff --git a/src/hackbench/hackbench.c b/src/hackbench/hackbench.c
index 8d98955..f3ef7c5 100644
--- a/src/hackbench/hackbench.c
+++ b/src/hackbench/hackbench.c
@@ -1,5 +1,6 @@
 /* Test groups of 20 processes spraying to 20 receivers */
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <sys/types.h>
@@ -12,6 +13,11 @@
 static unsigned int loops = 100;
 static int use_pipes = 0;
 
+struct children_pairs {
+        pid_t  sender;
+        pid_t  receiver;
+};
+
 static void barf(const char *msg)
 {
         fprintf(stderr, "%s (error: %s)\n", msg, strerror(errno));
@@ -101,38 +107,43 @@ static void receiver(unsigned int num_packets,
 /* One group of senders and receivers */
 static unsigned int group(unsigned int num_fds,
                           int ready_out,
-                          int wakefd)
+                          int wakefd,
+                          struct children_pairs *childp)
 {
         unsigned int i;
         unsigned int out_fds[num_fds];
 
         for (i = 0; i < num_fds; i++) {
                 int fds[2];
+                pid_t pid = -1;
 
                 /* Create the pipe between client and server */
                 fdpair(fds);
 
                 /* Fork the receiver. */
-                switch (fork()) {
+                switch ((pid = fork())) {
                 case -1: barf("fork()");
                 case 0:
                         close(fds[1]);
                         receiver(num_fds*loops, fds[0], ready_out, wakefd);
                         exit(0);
                 }
-
+                childp->receiver = pid;
                 out_fds[i] = fds[1];
                 close(fds[0]);
         }
 
         /* Now we have all the fds, fork the senders */
         for (i = 0; i < num_fds; i++) {
-                switch (fork()) {
+                pid_t pid = -1;
+
+                switch ((pid = fork())) {
                 case -1: barf("fork()");
                 case 0:
                         sender(num_fds, out_fds, ready_out, wakefd);
                         exit(0);
                 }
+                childp->sender = pid;
         }
 
         /* Close the fds we have left */
@@ -150,6 +161,7 @@ int main(int argc, char *argv[])
         unsigned int num_fds = 20;
         int readyfds[2], wakefds[2];
         char dummy;
+        struct children_pairs *children = NULL;
 
         if (argv[1] && strcmp(argv[1], "-pipe") == 0) {
                 use_pipes = 1;
@@ -163,9 +175,13 @@ int main(int argc, char *argv[])
         fdpair(readyfds);
         fdpair(wakefds);
 
+        children = calloc(num_groups, sizeof(struct children_pairs)+1);
+        if( !children )
+                barf("calloc() for children array");
+
         total_children = 0;
         for (i = 0; i < num_groups; i++)
-                total_children += group(num_fds, readyfds[1], wakefds[0]);
+                total_children += group(num_fds, readyfds[1], wakefds[0], &children[i]);
 
         /* Wait for everyone to be ready */
         for (i = 0; i < total_children; i++)
@@ -179,9 +195,13 @@ int main(int argc, char *argv[])
                 barf("Writing to start them");
 
         /* Reap them all */
-        for (i = 0; i < total_children; i++) {
+        for (i = 0; i < num_groups; i++) {
                 int status;
-                wait(&status);
+                waitpid(children[i].sender, &status, 0);
+                if (!WIFEXITED(status))
+                        exit(1);
+
+                waitpid(children[i].receiver, &status, 0);
                 if (!WIFEXITED(status))
                         exit(1);
         }
@@ -191,5 +211,7 @@ int main(int argc, char *argv[])
         /* Print time... */
         timersub(&stop, &start, &diff);
         printf("Time: %lu.%03lu\n", diff.tv_sec, diff.tv_usec/1000);
+
+        free(children);
         exit(0);
 }