I have an application that has been in production for several years and the
data access code has not been updated in a very long time. Over the last
couple of days I've seen poor latency for a significant number of
requests. From the log statements I see almost the entirety of time --
over 20 seconds -- is being spent fetching a single record from the
datastore by record id. Some requests immediately before or after these
still perform in the expected few hundred ms time.
The java code is using an older version of JDO:
datanucleus-appengine-1.0.10.final.jar
datanucleus-core-1.1.5.jar
jdo2-api-2.3-eb.jar
and the relevant data access code is:
private CachedImage queryDatastore(String lookupKey)
{
PersistenceManager pm = null;
CachedImage cachedImage = null;
try
{
pm = PMF.get().getPersistenceManager();
cachedImage = pm.getObjectById(CachedImage.class, lookupKey);
}
catch(JDOObjectNotFoundException e)
{
// not found, do nothing and return null
}
finally
{
if (pm != null)
{
pm.close();
}
}
return cachedImage;
}
The datastore records are organized and accessed by namespaces and the
total size of the datastore is small 3GB. The namespace I've been testing
against
is also tiny -- several thousand records and less than 40Mb in size.
Is anyone else experiencing similar issues with the datastore? Does anyone
have any ideas if something has changed with GAE or specifically its
support for JDO
that may explain why performance is suddenly so bad?
Thanks,
David
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