Forum OpenACS Development: Re: Strange problem with util_memoize flush

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Posted by Gustaf Neumann on
My "hope" was that you had some misconfiguration, but so far, i can't see anything obvious. How large is your util_memoize cache? I tried for a while to reproduce the problem with variations of
string length [util_memoize {string repeat abcde 30000}]
in the ds/shell, but could not reproduce the problem. Can you produce a sequence of util_memoize commands like the one above (e.g. loop) to reproduce the problem on your site?
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Posted by Eduardo Santos on
Hi Gustaf,

My cache is 200000 MB large, and the problem happens clearly when the cache gets full. I can see from AOLServer stats the following info:

Cache Max Current Entries Flushes Hits Misses Hit Rate
xowiki_cache 200000 2026 6 0 110 106 50%
xotcl_object_type_cache 10000 346 37 35809 92407 35846 72%
xotcl_object_cache 400000 19591 16 0 6152 16 99%
util_memoize 200000 199939 2852 7557 1109321 26009 97%
secret_tokens 32768 600 15 0 300 15 95%
nsfp:ct-gcie 5120000 934418 137 0 1557 137 91%
nsfp: 5120000 0 0 0 0 0 0%
ns:dnshost 100 0 0 0 0 0 0%
ns:dnsaddr 100 5 5 0 230 5 97%
ds_page_bits 10000000 0 0 0 0 0 0%
db_cache_pool 200000 20 2 0 7841 2 99%

When the cache gets close to the limit and the system try to reload it, it fails and the reloading proccess lasts forever.

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Posted by Gustaf Neumann on
The statistics indicate that your util_memoize cache is 200000 bytes, not MB! I do not understand the last sentence. What exactly is "it"?

Yet another attempt to help you:
Run the following script in your ds/shell:

foreach i {1 2 3 4} {util_memoize [list string repeat abcde 3998$i]}
append _ "nearly full: " [ns_cache_size util_memoize] " "
foreach i {4 3 2 1} {util_memoize [list string repeat abcde $i]}
append _ "over full: " [ns_cache_size util_memoize]
The first line fills your cache to the size 199931 bytes. The third line crosses in several steps the 200k border. Does this work on your machine?