add script counting network connections (arangodb#6754)

dothebart · neunhoef · commit 94805aad7c26 · 2018-10-08T12:43:22.000+02:00
This was added (and is currently not being used) to find a problem where a server in shutdown would hammer the agency with new connections. It was decided to implement a corresponding monitoring directly in the monitoring system (ganglia) rather than in the context of `testing.js`. Nevertheless, the script is retained for posteriority here.
diff --git a/scripts/analyzeNetworkSocketUsage.sh b/scripts/analyzeNetworkSocketUsage.sh
@@ -0,0 +1,30 @@
+#!/bin/bash
+# we first count open sockets in total on the system:
+echo "open sockets: "
+F="/tmp/$$_netstat.log"
+# we store it in a temporary file, since gatherng this information may become expensive if
+# its more then some thousand connections:
+netstat -n |grep ^tcp > $F
+C=$(wc -l < "$F")
+echo $C
+# if this outdoes a sane number, lets go into detail.
+if test "$C" -gt 1024; then
+    # we use lsof to find all tcp sockets and which processes own them.
+    LF="/tmp/$$_lsof.log"
+    lsof -n -iTCP > "$LF"
+    # we group all sockets by target ip:port
+    for sockets in $(grep ^tcp $F | sed -e "s;  *; ;g"  |cut -d ' '  -f 5 |sort -u ) ; do
+        # count the connections to one ip:port
+	SC=$(grep "$sockets" $F |wc -l)
+	if test "$SC" -gt "16"; then
+            # if the connection outoes a sane figure, we want to count & output them:
+	    echo "$sockets - $SC"
+            # and here we want to know which processes are attached to them.
+            # this will output one line per active connection, so this may become much:
+	    grep "$sockets" "$LF"
+	fi
+    done
+    rm "$LF"
+fi
+rm "$F"
+
