From: Eric S. Raymond <esr@thyrsus.com>
Date: Fri, 28 Sep 2012 19:21:30 +0000 (-0400)
Subject: Prevent empty-queue check from eating the CPU.
X-Git-Tag: 1.1~3
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=4d040db8a6ce6d889d1d8179b308ff310fb3bb21;p=irker.git

Prevent empty-queue check from eating the CPU.
---

diff --git a/BUGS b/BUGS
index 44b5100..12564e5 100644
--- a/BUGS
+++ b/BUGS
@@ -1,13 +1,4 @@
 			KNOWN BUGS
 
-We apologize for the rough edges on this software.  The initial release
-was somewhat rushed by the sudden death of cia.vc in late September 2012;
-a replacement needed to be fielded immediately.
-
-* Testing has been minimal.
-
-* There is one report of unexplainedly high CPU usage by irkerd when
-  processing UDP requests.
-
 * Despite what the header comment implies, the URL prefix and message template
   in irkerhook.py can at present only be modified by hacking the script.
diff --git a/NEWS b/NEWS
index 8ab0826..d6014ce 100644
--- a/NEWS
+++ b/NEWS
@@ -3,4 +3,7 @@
 1.0 @ 2012-09-27
   First production version, somewhat rushed by the sudden death of cia.vc.
 
+1.1 @ 2012-09-28
+  Add a delay to avoid threads spinning on the empty-queue-check, eating CPU.
+
 
diff --git a/README b/README
index 2f151d0..54b8553 100644
--- a/README
+++ b/README
@@ -15,7 +15,7 @@ and passes them to a local irker instance. Find it here:
 
     https://github.com/nenolod/irker-cia-proxy
 
-Due to the abrupt death of cia.vc in late September 2012 the
+Due to the abrupt death of cia.vc on September 24 2012 the
 initial release of this software was a bit rushed.  See the file
 BUGS for known problems.
 
diff --git a/irkerd b/irkerd
index 3187e7f..905c12d 100755
--- a/irkerd
+++ b/irkerd
@@ -34,6 +34,7 @@ DISCONNECT_TTL = (24 * 60 * 60)	# Time to live, seconds from last connect
 UNSEEN_TTL = 60			# Time to live, seconds since first request
 CHANNEL_MAX = 18		# Max channels open per socket (default)
 ANTI_FLOOD_DELAY = 0.125	# Anti-flood delay after transmissions, seconds
+ANTI_BUZZ = 0.09		# Anti-buzz delay after queue-empty check
 
 # No user-serviceable parts below this line
 
@@ -41,7 +42,7 @@ import sys, json, getopt, urlparse, time
 import threading, Queue, SocketServer
 import irc.client, logging
 
-version = "1.0"
+version = "1.1"
 
 # Sketch of implementation:
 #
@@ -152,6 +153,13 @@ class Connection:
                     self.connection.close()
                     self.connection = None
                     self.status = "disconnected"
+                else:
+                    # Prevent this thread from hogging the CPU by pausing
+                    # for just a little bit after the queue-empty check.
+                    # As long as this is less that the duration of a human
+                    # reflex arc it is highly unlikely any human will ever
+                    # notice.
+                    time.sleep(ANTI_BUZZ)
             elif self.status == "disconnected" \
                      and time.time() > self.last_xmit + DISCONNECT_TTL:
                 # Queue is nonempty, but the IRC server might be down. Letting