In case we have multiple processes using StarPU (eg. with MPI), we need to

generate multiple traces at the same time, so we suffix the trace file's name
with the pid of the process.

src/common/fxt.c

@@ -38,9 +38,19 @@ static void profile_set_tracefile(char *fmt, ...)
 	va_start(vl, fmt);
 	vsprintf(PROF_FILE_USER, fmt, vl);
 	va_end(vl);
-	strcat(PROF_FILE_USER, "_user_");
-	if ((user = getenv("USER")))
-		strcat(PROF_FILE_USER, user);
+
+	user = getenv("USER");
+	if (!user)
+		user = "";
+
+	int pid = getpid();
+
+	char suffix[128];
+	snprintf(suffix, 128, "_user_%s_%d", user, pid);
+
+	strcat(PROF_FILE_USER, suffix);
+
+
 }