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antirez/test-lru.rb

Last active August 29, 2015 13:57
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test-lru.rb
require 'rubygems'
require 'redis'
r = Redis.new
r.config("SET","maxmemory","2000000")
r.config("SET","maxmemory-policy","allkeys-lru")
r.config("SET","maxmemory-samples",1000)
r.config("RESETSTAT")
r.flushall
puts <<EOF
<html>
<body>
<style>
.box {
width:5px;
height:5px;
float:left;
margin: 1px;
}
.old {
border: 1px black solid;
}
.new {
border: 1px green solid;
}
.ex {
background-color: #666;
}
</style>
<pre>
EOF
# Fill
oldsize = r.dbsize
id = 0
while true
id += 1
r.set(id,"foo")
newsize = r.dbsize
break if newsize == oldsize
oldsize = newsize
end
inserted = r.dbsize
first_set_max_id = id
puts "#{r.dbsize} keys inserted"
# Access keys sequencially
puts "Access keys sequencially"
(1..first_set_max_id).each{|id|
r.get(id)
# sleep 0.001
}
# Insert more 50% keys. We expect that the new keys
half = inserted/2
puts "Insert enough keys to evict half the keys we inserted"
add = 0
while true
add += 1
id += 1
r.set(id,"foo")
break if r.info['evicted_keys'].to_i >= half
end
puts "#{add} additional keys added."
puts "#{r.dbsize} keys in DB"
# Check if evicted keys respect LRU
# We consider errors from 1 to N progressively more serious as they violate
# more the access pattern.
errors = 0
e = 1
edecr = 1.0/(first_set_max_id/2)
(1..(first_set_max_id/2)).each{|id|
e -= edecr if e > 0
e = 0 if e < 0
if r.exists(id)
errors += e
end
}
puts "#{errors} errors!"
puts "</pre>"
# Generate the graphical representation
(1..id).each{|id|
# Mark first set and added items in a different way.
c = "box"
if id <= first_set_max_id
c << " old"
else
c << " new"
end
# Add class if exists
c << " ex" if r.exists(id)
puts "<div class=\"#{c}\"></div>"
}
# Close HTML page
puts <<EOF
</body>
</html>
EOF
@antirez
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antirez commented Mar 19, 2014

To use this program in a small time-scale without sleep calls, use the following patch for Redis:

diff --git a/src/db.c b/src/db.c
index 950ebe4..0b19553 100644
--- a/src/db.c
+++ b/src/db.c
@@ -50,7 +50,7 @@ robj *lookupKey(redisDb *db, robj *key) {
          * Don't do it if we have a saving child, as this will trigger
          * a copy on write madness. */
         if (server.rdb_child_pid == -1 && server.aof_child_pid == -1)
-            val->lru = server.lruclock;
+            val->lru = mstime() & REDIS_LRU_CLOCK_MAX;
         return val;
     } else {
         return NULL;

@antirez
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antirez commented Mar 19, 2014

p.s. also apply commit e150ec7 to your tree, or alternatively restart the Redis instance before every script execution.

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