Ok, not yet figured out why one machine clone crashes while the other
doesn't, but am trying to patch each part of ODBC without taking
production
machine out of service. (It's a very productive ecommerce site)
What we've figured out:
When witango gets a hit that requires a connection to mysql, it looks
for an
available connection using that DSN. If it's available, it uses it.
If there are current connections, but they're busy, it spawns another
A pile of hits at the same moment creates a small stack of data
connections.
Up to 8.
Subsequently, when traffic is slower, witango picks one of the data
connections and lets the others age. Don't know how it picks one vs
another,
but that's what it does. That leaves the others aging out and should
expire
when they hit the datasourcelife setting.
That's where the trouble comes. Rather than die, the connections get
hung
up, cause CPU usage to jack up, eventually cause new hits to get hung
and
the witango server crashes. When they're tied up, they aren't
available to
be used, but are technically alive, I guess, because if witango has
selected
one of those, visitors get hung up.
So, after updating this piece and that piece of ODBC, it still does
the same
thing and JDBC has its own profile of random crashes.
So, while we sift though the finger-pointing and terse instructions,
we've
jury rigged a way to prevent crashes.
On another witango server, we've created a cron to hit the sick
server
every
hour with 8 <@URL>s that each hit a database. That makes sure that
the
8
connection requests are simultaneous and generate 8 connections. The
connections are alive, but aging, these 8 refresh them all. The
counter goes
back to 1.
Then, we set the datasource life to 24 hours. That gives the cron 24
opportunities to restart the timer on every datasource.
Seems to be working.
Net net: if datasource expiry is causing crashes, don't ever let one
expire.
-----------------------------------------
Roland Dumas
Roberts Information Services
310 W. Bellevue Avenue
San Mateo CA 94402
650-347-1373
415-412-9300 (cell)
[EMAIL PROTECTED]
SMS: http://new.servqual.com/html/sms.tml
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