Add VRM Jobid to the send process infos

which only works if the "SLURM_VRM_JOBID" environment variable is set. If that is not the case, the message looks just as before. That means that if the env var is set then the locserv (test server) will throw an error since it will not be able to parse the message.

Also add a troubleshooting entry in the README.

ompi/communicator/comm_init.c

@@ -35,6 +35,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/socket.h>
+#include <sys/types.h>
 #include <sys/un.h>
 #include <unistd.h>
 #include <string.h>
@@ -57,6 +58,8 @@
 #define FD_STDIN 0
 #define BUFFLEN 128
 
+#define JOBID_ENV_VAR "SLURM_VRM_JOBID"
+
 /*
 ** Table for Fortran <-> C communicator handle conversion
 ** Also used by P2P code to lookup communicator based
@@ -141,11 +144,20 @@ static int get_modified_ranks(uint32_t jobid, uint32_t vpid, size_t size, opal_v
 
     pid_t pid = getpid();
 
+    const char * vrm_jobid = getenv(JOBID_ENV_VAR);
+    char vrm_jobid_with_leading_comma[sizeof(uint64_t) + 1] = "";
+    if (NULL != vrm_jobid) {
+        char comma = ',';
+        strncat(vrm_jobid_with_leading_comma, &comma, 1);
+        strcat(vrm_jobid_with_leading_comma, vrm_jobid);
+        printf("TEST: %s", vrm_jobid_with_leading_comma);
+    }
+
     char info_to_send[BUFFLEN];
     memset(info_to_send, 0, BUFFLEN);
     snprintf(info_to_send, BUFFLEN,
-            "{\"msg_type\": 128, \"msg_data\": \"%d,%u,%u,%zu\"}",
-            pid, vpid, jobid, size);
+            "{\"msg_type\": 128, \"msg_data\": \"%d,%u,%u,%zu%s\"}",
+            pid, vpid, jobid, size, vrm_jobid_with_leading_comma);
 
     // TODO: endianness
     uint32_t msg_length = strlen(info_to_send) + 1;