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POappengine jpa cache level 2 performance is bad
 

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  1. POappengine jpa cache level 2 performance is bad
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    <p>appengine java sdk 1.6.4.1 datanucleus jpa2.0.0 datanucleus cache 3.0.1</p> <p>hi all</p> <p>i am using the DN cache level 2 plugin.</p> <pre><code>&lt;property name="datanucleus.cache.level2.type" value="javax.cache"/&gt; &lt;property name="datanucleus.cache.level2.cacheName" value="xxxxx"/&gt; </code></pre> <p>i noticed a performance issue with a straight forward query.</p> <pre><code>Query query = em.createQuery("Select m.key from MessageUser m " + "where " + " m.userKeyList = :userKey " + "AND m.date &gt; :date ORDER BY m.date DESC"); </code></pre> <p>with the cache ON it execute in 1159 ms, cache OFF 86 ms.</p> <p>something is clearly wrong. from the appstats trace the cache version is retrieving each entity in a serial manner from memcache.</p> <p>any explanation on whether this is expected or have i stuffed up?</p> <p>cache OFF</p> <pre><code>(1) 2012-04-12 06:19:38.737 "GET /timeline/status?id=49001&amp;sincedate=1333485300" 200 real=86ms api=0ms overhead=0ms (6 RPCs) @11ms datastore_v3.RunQuery real=10ms api=241ms @31ms datastore_v3.Get real=7ms api=208ms @4ms datastore_v3.BeginTransaction real=4ms api=0ms @52ms datastore_v3.Get real=7ms api=8ms @65ms datastore_v3.Get real=4ms api=0ms @78ms datastore_v3.Commit real=4ms api=0ms </code></pre> <p>cache ON</p> <pre><code>9) 2012-04-12 05:54:24.385 "GET /timeline/status?id=49001&amp;sincedate=1333485300" 200 real=1159ms api=0ms overhead=0ms (109 RPCs) @13ms datastore_v3.RunQuery real=12ms api=241ms @28ms memcache.Get real=2ms api=0ms @33ms memcache.Get real=2ms api=0ms @37ms memcache.Get real=3ms api=0ms @42ms memcache.Get real=2ms api=0ms @47ms memcache.Get real=2ms api=0ms @50ms memcache.Get real=2ms api=0ms @54ms memcache.Get real=2ms api=0ms @57ms memcache.Get real=2ms api=0ms &lt;repeat this for another 50 or60 times @3ms datastore_v3.BeginTransaction real=4ms api=0ms @1126ms datastore_v3.Get real=5ms api=8ms @1134ms memcache.Get real=3ms api=0ms @1139ms memcache.Get real=2ms api=0ms @1143ms datastore_v3.Get real=4ms api=0ms @1153ms datastore_v3.Commit real=3ms api=0ms </code></pre> <p>the code that iterates the entity list</p> <pre><code>List&lt;Message&gt; list = messageDAO.findSinceDate(userKey, sinceDate); JSONArray jsonList = new JSONArray(); for (Message message : list) { item.put("id", message.getKey().getId()); item.put("name", message.getName()); } </code></pre>
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    1. COwhy not present your code where you are accessing the elements of the query result ? where you access them one-by-one? and then the log
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    2. CO@DataNucleus i have added the code that iterates the query results. as can be seen they are accessed in a iteration. what are thinking is the issue?
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